Upload
others
View
4
Download
0
Embed Size (px)
Citation preview
Comparing Current Screening Modalities for Colorectal
Cancer and Precancerous Lesions: Is Colonoscopy
the Method of Choice?
Puneet K. Singh*
Saba University School of Medicine, Saba, Dutch Caribbean
*Corresponding author: Puneet K. Singh; [email protected]
Colorectal cancer (CRC) is the third most common form of cancer and the second leading cause of cancer death in the Western
world. Presently, screening tools such as colonoscopy, sigmoidoscopy, fecal occult blood test (FOBT) and computed tomographic
colonography (CTC) are available for CRC screening. The debate over which screening tool is most effective in detecting CRC and
precancerous lesions is ongoing. Many recent studies have identified colonoscopy as the most sensitive and specific screening
modality for CRC. However, a number of factors have prevented colonoscopy from being widely accepted. Less invasive techniques
such as sigmoidoscopy and CTC are growing in popularity among physicians and patients who are apprehensive about colonoscopy
screening; although many still are yet to experience the procedure first-hand. This literature review will attempt to validate the
growing theory that colonoscopy is superior to other modalities for the diagnosis and screening of CRC and reduces the risk of CRC
mortality. In order to do so, the paper will compare the risks and benefits of colonoscopy to sigmoidoscopy and CTC. It will further
look at the different aspects that encompass a patient’s decision to partake in screening, such as basic knowledge about CRC, history
of CRC in the family, advice from physicians and individual beliefs about what screening entails. Finally, this paper will propose ways
in which colonoscopy screening can be improved and thus surpass other screening modalities to universally become the first choice
for CRC screening.
Keywords: colonoscopy; colorectal neoplasms; sigmoidoscopy; CT colonography; mass screening.
INTRODUCTIONolorectal cancer (CRC) is the third most commonform of cancer and the second leading cause of
cancer death in the Western world, equally affectingboth men and women.1 In 2012, the United States hadan estimated 143,460 individuals diagnosed with CRCand 51,690 related deaths.2 The vast majority of CRCswithin North America are sporadic with fewer than5% directly related to chronic inflammatory diseases orhereditary causes of CRC, such as familial adenomatouspolyposis (FAP) and hereditary non-polyposis coloncancer (HNPCC).1 Sporadic CRC is due to mutationscausing histological changes within the luminal aspectof colonic mucosa which slowly progress to benignadenomatous polyps of varying types: tubular, tubulo-villous and villous.3 These precancerous lesions canincrease in size, become dysplastic and eventuallytransform into overt carcinomas. The slow progressionof these changes causes age to be one of the greatestrisk factors for CRC. It is estimated that 90% of allCRC cases occur after the age of 50 in both men andwomen.4 Along with family history and age, othersignificant risk factors for CRC include obesity, tobacco
and alcohol abuse, stress, inflammatory bowel diseases(e.g., ulcerative colitis) and diet.3 With its long list of riskfactors and worldwide prominence, it is imperative thathealth care providers and patients become moreknowledgeable about CRC and the ways in which todetect its precursor lesions at early and docile stages.
A number of different techniques are currently em-ployed to screen for polyps and CRC. Epidemiologicalstudies have shown a decline in the incidence andmortality of CRC over the years, which is primarilyattributed to increases in screening test use.5 Specificguidelines outlining which tests should be used andwhen they should be administered have been estab-lished by a number of prominent medical societies andorganizations. The United States Preventative ServicesTask Force (USPSTF) recommends three main screeningmethods: high-sensitivity fecal occult blood test (FOBT)annually, flexible sigmoidoscopy every 5 years withFOBT every 3 years or colonoscopy every 10 years.5 TheAmerican Cancer Society and The American Collegeof Physicians’ (ACP) recommendations mirror those ofUSPSTF. These bodies also agree that patients with one
Review Article
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 034
or more first-degree relatives with CRC, or a heredi-tary syndrome that predisposes them to CRC, shouldreceive screening in the second or third decade of life,6
while in average-risk patients, screening should bedone between the ages of 50 and 75.7 There is a strongbelief that screening after the age of 75 may no longerbe beneficial for patients and may in fact cause harm.4,6
Since the 1990s, the dominant screening test for CRCin the United States has been colonoscopy.8 Colono-scopy allows for direct visualization of the entire colon,from the appendiceal orifice to the dentate line,and also facilitates biopsy sampling or polypectomy oflesions that may appear abnormal. However, there is stillan ongoing debate in the medical community overwhich screening test is superior in the prevention anddetection of CRC. Moreover, with the introductionof newer screening methods such as Computed Tomo-graphic Colonography (CTC) and fecal DNA testing,choosing the best screening method has become moredifficult for both physicians and patients.
This paper will review both the advantages and dis-advantages of colonoscopy, sigmoidoscopy and CTC.The paper will forgo discussion of FOBT as it attemptsto focus on invasive screening techniques that aremore procedurally similar to colonoscopy so thataspects of the patient experience during each techni-que can be appropriately compared. Other factorsaffecting a patient’s decision to engage in regular CRCscreening and the role of primary care providers ininforming their patients about each method will alsobe analyzed.
Through a contemporary literature review, this paperwill examine whether colonoscopy is the superiormethod for the diagnosis and screening of CRC, andthus whether it has a greater capacity to reduce therisk of death from CRC as compared to other screeningmodalities.
METHODSThe main database used to obtain scholarly articles
cited in this literature review was PubMed at www.pubmed.org. A number of different search strategieswere used to narrow down articles. One strategyincluded keywords such as: ((colon cancer) AND (colo-noscopy) AND (surveillance)). Another strategy used‘colonoscopy’, ‘epidemiology’ and ‘colorectal neoplasms’as MeSH terms with ‘mass screening OR screening.’Subsequent searches focused on other modalities ofCRC screening with the use of ‘sigmoidoscopy’ and‘CT colonography’ as MeSH terms and with the sub-heading ‘therapeutic use.’ The filters used in all searches
included: past 5 years (2008�2013), clinical trial, rando-mized control trials (RCTs), humans, English and full textavailable. A few articles were also attained from otherdatabases such as Medscape, EBSCOhost and GoogleScholar using variations of the search strategies, key-words and filters described above.
In all articles selected, the study population of in-terest was high- and low-risk patients, aged 50 orolder, living within North America and other developednations. Other inclusion criteria included choosingarticles that were published in prominent journals orby recognized and valued medical organizations.
Criteria used to exclude articles from this paperinclude factors such as a small study population andarticles categorized as ‘review articles’, although alimited number were consulted to obtain relevantbackground information on the pathophysiology, epi-demiology and diagnosis of CRC.
Articles that met these criteria were then compiledinto an ‘Evidence Table’ (Table 1) that outlines the keyfindings of each.
RESULTS
Comparing Colonoscopy to Sigmoidoscopy and CTC
ColonoscopyColonoscopy is a screening method that allows
inspection of the entire colon and enables biopsy ofneoplastic lesions through polypectomy. This methodis conducted under sedation and is currently theleading tool for CRC screening.8 Many of the presentlyknown benefits of colonoscopy stem from population-based cohort studies that analyze the effects ofcolonoscopy on incidence and mortality amongcommunities around the world. In Ontario, Canada,Rabeneck et al9 conducted a large prospective studybetween 1993 and 2006 where they found the ratesof complete colonoscopy screening increased in allregions of the province. Within the population thatunderwent screening, the incidence rates and mortalityrates of CRC were lower in the younger age group (50�69 years) and lower for women within all age groups.When mortality rate was adjusted for confoundingfactors associated with increased risk of CRC death,such as increased age, male gender, lower income andrural residence, greater colonoscopy use was overallassociated with decreased mortality from CRC. Further-more, the study identified that for every 1% increasein colonoscopy rates in the cohort’s individual regionof residence (each participant was assigned to 1 of13 regions based on their address in Ontario), there
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 035
Ta
ble
1.
Evid
en
ceta
ble
ou
tlin
ing
arti
cle
san
alyz
ed
inth
isre
vie
w
Firs
tau
tho
rD
ate
of
pu
blic
atio
nSt
ud
yd
esi
gn
Leve
lo
fe
vid
en
ceSt
ud
yp
op
ula
tio
nT
he
rap
yo
re
xpo
sure
Ou
tco
me
/re
sult
s
Ad
ler,
An
dre
as2
01
3P
rosp
ect
ive
coh
ort
wit
ho
ut
con
tro
ls
42
1co
lon
osc
op
ists
we
rest
ud
ied
fro
mp
riva
tep
ract
ice
sin
Be
rlin
,b
etw
ee
nO
ct.
20
06
and
Mar
,2
00
8.
Ove
rall,
ato
talo
f1
2,1
34
colo
no
sco
pie
sw
ere
exa
min
ed
.
Co
lon
osc
op
yT
hre
ep
atie
nt
fact
ors
corr
ela
ted
wit
had
en
om
ad
ete
ctio
nra
te(A
DR
):ag
e,
sex
and
low
qu
alit
yo
fb
ow
el
pre
par
atio
n.
Fact
ors
that
acco
un
ted
for
41
.4%
of
inte
r-p
hys
icia
nva
riab
ility
inA
DR
incl
ud
ed
:th
en
um
be
ro
fC
ME
me
eti
ng
sat
ten
de
dan
dd
iffe
ren
ces
ine
qu
ipm
en
tu
sed
du
rin
gsc
ree
nin
g.
Atk
in,
We
nd
y2
01
3R
CT
11
,58
0p
atie
nts
,5
5ye
ars
or
old
er
(me
dia
nag
ew
as6
8ye
ars;
ran
ge
61�7
5),
wit
hsy
mp
tom
ssu
gg
est
ive
of
CR
C(c
han
ge
inb
ow
el
hab
its,
rect
alb
lee
din
go
rab
do
min
alp
ain
)fr
om
21
UK
ho
spit
als.
1,0
47
we
rera
nd
om
lyas
sig
ne
dto
colo
no
sco
py
and
53
3as
sig
ne
dto
CT
C.
86
4(5
5%
)o
fth
eco
ho
rtw
ere
wo
me
n.
Pat
ien
tsw
ere
recr
uit
ed
be
twe
en
Mar
.2
00
4an
dD
ec.
20
07
.
CT
Can
dco
lon
osc
op
y1
60
(30
%)
pat
ien
tsin
the
CT
Cg
rou
ph
adad
dit
ion
alco
lon
icin
vest
igat
ion
com
par
ed
wit
h8
6(8
.2%
)in
the
colo
no
sco
py
gro
up
.A
lmo
sth
alf
the
refe
rral
saf
ter
CT
Cw
ere
for
smal
l(B
10
mm
)p
oly
ps
or
clin
ical
un
cert
ain
ty.
De
tect
ion
rate
so
fC
RC
or
larg
ep
oly
ps
we
re1
1%
for
bo
thp
roce
du
res.
CT
Cm
isse
d1
of
29
CR
Can
dco
lon
osc
op
ym
isse
dn
on
e(o
f5
5)
Bax
ter,
Nan
cyN
.2
00
9C
ase
con
tro
l3
10
,29
2ca
sep
atie
nts
and
51
,46
0co
ntr
ols
we
rep
art
of
this
stu
dy
po
pu
lati
on
.Fi
veco
ntr
ols
mat
che
db
yag
e,
sex,
ge
og
rap
hic
loca
tio
nan
dso
cio
eco
no
mic
stat
us
we
rera
nd
om
lyse
lect
ed
for
eac
hca
sep
atie
nt.
Par
tici
pan
tsw
ere
be
twe
en
the
age
so
f5
2an
d9
0w
ho
rece
ive
da
CR
Cd
iag
no
sis
fro
mJa
n.
19
96
toD
ec.
20
01
and
die
do
fC
RC
by
De
c.2
00
3.
Co
lon
osc
op
yC
om
ple
teco
lon
osc
op
yw
asst
ron
gly
asso
ciat
ed
wit
hfe
we
rd
eat
hs
fro
mle
ft-s
ide
dC
RC
bu
tn
ot
fro
mri
gh
t-si
de
dC
RC
Bax
ter,
Nan
cyN
.2
01
2C
ase
con
tro
l3
Ato
tal
of
9,4
58
case
sw
ere
ide
nti
fie
d.
Pat
ien
tsw
ere
age
d7
0�8
9an
dd
iag
no
sed
wit
hC
RC
be
twe
en
Jan
.1
99
8an
dD
ec.
20
02
.T
hre
eco
ntr
ols
(pat
ien
tsw
ith
ou
tC
RC
)w
ere
mat
che
dto
eac
hca
se.
Th
ep
rim
ary
exp
osu
rein
the
case
sw
asco
lon
osc
op
yp
refo
rme
dfr
om
1Ja
n.
19
91
to6
mo
nth
sb
efo
reth
ere
fere
nce
dat
e.
All
case
and
con
tro
ld
ata
we
reco
llect
ed
fro
mth
eSE
ER-M
ed
icar
ed
ata.
Co
lon
osc
op
yC
olo
no
sco
py
isas
soci
ate
dw
ith
are
du
ced
risk
of
de
ath
fro
mC
RC
,w
ith
ast
ron
ge
rd
ete
ctio
nra
tefo
rd
ista
lvs
.p
roxi
mal
CR
C.
Th
eo
vera
llas
soci
atio
no
fre
du
ced
risk
of
de
ath
was
stro
ng
est
ifco
lon
osc
op
yw
asp
erf
orm
ed
by
ag
astr
oe
nte
rolo
gis
t,as
op
po
sed
tosu
rge
on
so
rp
rim
ary
care
pro
vid
ers
.
Is Colonoscopy the Method of Choice? Puneet K. Singh
036 Medical Student Research Journal MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Ta
ble
1(C
on
tin
ued
)
Firs
tau
tho
rD
ate
of
pu
blic
atio
nSt
ud
yd
esi
gn
Leve
lo
fe
vid
en
ceSt
ud
yp
op
ula
tio
nT
he
rap
yo
re
xpo
sure
Ou
tco
me
/re
sult
s
Bre
tag
ne
,Je
an-F
ran
cois
20
10
Re
tro
spe
ctiv
eco
ho
rt3
Eig
hte
en
en
do
sco
pis
tsw
ere
use
din
this
stu
dy;
14
wo
rke
din
pri
vate
pra
ctic
ean
d4
wo
rke
din
pu
blic
ho
spit
als.
Th
esc
ree
nin
gg
rou
pin
clu
de
das
ymp
tom
atic
me
nan
dw
om
en
age
db
etw
ee
n5
0an
d7
4w
ith
no
oth
er
risk
fact
or
for
CR
C.
Th
est
ud
yw
asco
nd
uct
ed
be
twe
en
20
03
and
20
07
inIll
ee
t-V
ilan
e,
Bri
ttan
y.T
he
firs
tro
un
do
fsc
ree
nin
gw
asin
20
03
and
20
04
wit
h2
13
,63
5p
arti
cip
ants
and
the
seco
nd
rou
nd
in2
00
5an
d2
00
6w
ith
22
4,5
04
par
tici
pan
ts.
Co
lon
osc
op
yIn
tere
nd
osc
op
icva
riab
ility
had
no
eff
ect
on
can
cer
de
tect
ion
ina
scre
en
ing
pro
gra
mw
ith
ah
igh
com
plia
nce
rate
wit
hco
lon
osc
op
yaf
ter
FOB
T;
ho
we
ver,
itd
idin
flu
en
ceth
eid
en
tifi
cati
on
of
ade
no
mas
.
Co
urt
ne
y,R
yan
J.2
01
3C
ase
seri
es
wit
ho
ut
con
tro
ls
41
,59
2at
-ris
kin
div
idu
als
(56�8
8ye
ars
of
age
)w
ere
ran
do
mly
sele
cte
dfr
om
the
Hu
nte
rC
om
mu
nit
ySt
ud
y(a
lon
git
ud
inal
com
mu
nit
yco
ho
rtin
Au
stra
lia)
be
twe
en
De
c.2
00
4an
dD
ec.
20
07
tota
kep
art
ina
qu
est
ion
nai
reb
ym
ail.
1,1
17
par
tici
pan
tsre
turn
ed
the
qu
est
ion
nai
res;
76
0re
spo
nd
en
tsw
ere
elig
ible
for
scre
en
ing
and
anal
ysis
.
Co
lon
osc
op
y6
3%
of
par
tici
pan
tsre
ceiv
ed
CR
Csc
ree
nin
g,
wit
hth
em
ajo
rity
be
ing
‘po
ten
tial
lyh
igh
risk
’p
arti
cip
ants
(84
%).
Th
ose
sig
nif
ican
tly
mo
relik
ely
toh
ave
rece
ive
dte
stin
gw
ere
age
db
etw
ee
n6
5an
d7
4an
dw
ho
had
atso
me
po
int
rece
ive
dsc
ree
nin
gad
vice
fro
mth
eir
fam
ilyp
hys
icia
n,
or
had
dis
cuss
ed
fam
ilyh
isto
ryo
fC
RC
wit
hth
eir
do
cto
r.2
1%
of
tho
sein
the
‘at
or
slig
htl
yab
ove
ave
rag
e-r
isk’
gro
up
had
rece
ive
dsc
ree
nin
gas
pe
ro
ffic
ial
scre
en
ing
gu
ide
line
s.G
uid
elin
es
we
resi
gn
ific
antl
ym
ore
like
lyto
be
follo
we
din
the
‘mo
de
rate
lyin
cre
ase
dri
sko
rp
ote
nti
ally
hig
hri
sk’
gro
up
s(4
5%
).C
olo
no
sco
py
wit
hin
5ye
ars
was
the
mo
stco
mm
on
lyre
com
me
nd
ed
gu
ide
line
and
was
sig
nif
ican
tly
mo
relik
ely
tob
ere
com
me
nd
ed
toin
div
idu
als
wit
hp
riva
tein
sura
nce
or
wh
oh
add
iscu
sse
dfa
mily
his
tory
of
CR
Cw
ith
ad
oct
or.
de
Wijk
ersl
oo
th,
Th
om
asR
.2
01
2R
CT
1T
his
stu
dy
was
of
8,8
44
Du
tch
citi
zen
sag
ed
50�7
4,
invi
ted
by
mai
lfo
rp
op
ula
tio
n-b
ase
dC
RC
scre
en
ing
inA
mst
erd
aman
dR
ott
erd
am,
be
twe
en
Jun
.2
00
9an
dA
ug
.2
01
0.
Invi
tati
on
sw
ere
ran
do
mly
allo
cate
d2
:1to
colo
no
sco
py
(5,9
24
)o
rC
TC
(2,9
20
)
Co
lon
osc
op
yan
dC
TC
Be
fore
scre
en
ing
,in
div
idu
als
exp
ect
ed
colo
no
sco
py
and
bo
we
lp
rep
arat
ion
tob
em
ore
bu
rde
nso
me
than
CT
Csc
ree
nin
g.
Ho
we
ver,
wh
en
ind
ivid
ual
sp
arti
cip
ate
din
scre
en
ing
,C
TC
was
sco
red
asm
ore
bu
rde
nso
me
than
colo
no
sco
py.
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 037
Ta
ble
1(C
on
tin
ued
)
Firs
tau
tho
rD
ate
of
pu
blic
atio
nSt
ud
yd
esi
gn
Leve
lo
fe
vid
en
ceSt
ud
yp
op
ula
tio
nT
he
rap
yo
re
xpo
sure
Ou
tco
me
/re
sult
s
Allo
cati
on
was
stra
tifi
ed
for
age
,se
x,SE
Sst
atu
sb
ase
do
nd
ata
of
Stat
isti
csN
eth
erl
and
sd
eW
ijker
slo
oth
,T
ho
mas
R.
20
12
RC
T1
Be
twe
en
Jun
.2
00
9an
dA
ug
.2
01
0,
8,8
44
ind
ivid
ual
sag
ed
50�7
5,
ne
ver
be
fore
scre
en
ed
for
CR
C,
we
rera
nd
om
lyal
loca
ted
tou
nd
erg
oe
ith
er
colo
no
sco
py
scre
en
ing
(5,9
24
)o
rC
TC
(2,9
20
).A
lloca
tio
nw
asb
ase
do
nag
e,
sex
and
soci
oe
con
om
icst
atu
s;d
ata
fro
mSt
atis
tics
Ne
the
rlan
ds.
Pat
ien
tsw
ere
fro
mth
eA
mst
erd
aman
dR
ott
erd
amre
gio
n.
Co
lon
osc
op
yan
dC
TC
Th
em
ost
fre
qu
en
tly
cite
dre
aso
ns
toac
cep
tsc
ree
nin
gw
ere
ear
lyd
ete
ctio
no
fp
recu
rso
rle
sio
ns
and
CR
C,
and
con
trib
uti
on
tosc
ien
ce.
Th
em
ost
fre
qu
en
tly
cite
dre
aso
ns
tod
ecl
ine
we
reth
eu
np
leas
antn
ess
of
the
exa
min
atio
n,
the
inco
nve
nie
nce
of
the
pre
par
atio
n,
ala
cko
fsy
mp
tom
san
d‘n
oti
me
/to
om
uch
eff
ort
’.El
de
rly
ind
ivid
ual
sci
ted
the
abse
nce
of
sym
pto
ms
asa
mo
resi
gn
ific
ant
reas
on
ton
ot
un
de
rgo
colo
no
sco
pie
sas
com
par
ed
toth
eo
vera
llst
ud
yp
op
ula
tio
n.
Th
em
ost
fre
qu
en
tly
cite
dre
aso
nfo
rd
ecl
inin
gco
lon
osc
op
yw
asth
eu
np
leas
antn
ess
of
the
exa
min
atio
n.
Fen
ton
,Jo
shu
aJ.
20
11
Pro
spe
ctiv
eco
ho
rt3
Th
est
ud
yp
op
ula
tio
nin
clu
de
dp
atie
nts
atte
nd
ing
app
oin
tme
nts
at2
acad
em
icp
rim
ary
care
clin
ics
�U
niv
ers
ity
of
Cal
ifo
rnia
,D
avis
,an
dM
ed
ical
Ce
nte
rin
Sacr
ame
nto
,C
A.,
be
twe
en
Sep
t.2
00
8an
dD
ec.
20
09
.5
0p
atie
nts
age
db
etw
ee
n5
0an
d7
5w
ere
elig
ible
for
CR
Cb
ase
do
nth
ecr
ite
ria
that
the
yh
adn
eve
rh
ad:
FOB
Td
uri
ng
the
pas
tye
ar,f
lexi
ble
sig
mo
ido
sco
py
du
rin
gth
ep
ast
5ye
ars,
colo
no
sco
py
in1
0ye
ars.
Inad
dit
ion
,2
0fa
mily
care
ph
ysic
ian
sw
ere
sele
cte
dfr
om
the
2cl
inic
s.
Co
lon
osc
op
yA
sco
mp
are
dto
pat
ien
tvi
sits
wit
ho
ut
CR
Csc
ree
nin
gd
iscu
ssio
n,
visi
tsw
ith
dis
cuss
ion
we
reas
soci
ate
dw
ith
incr
eas
ed
pe
rce
ive
dan
dsc
ree
nin
gin
ten
tio
naf
ter
the
visi
tb
ut
no
sig
nif
ican
tch
ang
ein
pe
rce
ive
db
en
efi
ts,
bar
rie
rso
rse
lf-e
ffic
acy.
Wit
hin
6m
on
ths,
17
of
38
pat
ien
ts(4
5%
)w
ho
dis
cuss
ed
scre
en
ing
com
ple
ted
scre
en
ing
com
par
ed
wit
h0
of
12
pat
ien
tsw
ho
did
no
td
iscu
sssc
ree
nin
g.
Gra
ser,
A.
20
09
Pro
spe
ctiv
eco
ho
rtw
ith
ou
tco
ntr
ols
43
11
asym
pto
mat
ic,
ave
rag
e-r
isk
adu
lts
(17
1m
en
and
14
0w
om
en
),ag
ed
be
twe
en
50
and
81
un
de
rwe
nt
sam
ed
aysc
ree
nin
go
f5
dif
fere
nt
scre
en
ing
inte
rve
nti
on
s.O
nly
30
7p
atie
nts
com
ple
ted
itin
full,
as4
sub
ject
sw
ith
dre
w.
Sig
mo
ido
sco
py
CT
C,
FIT
,FO
BT
,C
olo
no
sco
py
Sen
siti
viti
es
of
OC
,CT
C,F
S,FI
Tan
dFO
BT
for
adva
nce
dco
lon
icn
eo
pla
sia
we
re1
00
,96
.7.
83
.3,
32
and
20
%,
resp
ect
ive
ly.
Co
mb
inat
ion
of
FSw
ith
FIT
or
FOB
Td
idn
ot
incr
eas
ese
nsi
tivi
tyfo
rad
van
ced
CR
C.
Is Colonoscopy the Method of Choice? Puneet K. Singh
038 Medical Student Research Journal MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Ta
ble
1(C
on
tin
ued
)
Firs
tau
tho
rD
ate
of
pu
blic
atio
nSt
ud
yd
esi
gn
Leve
lo
fe
vid
en
ceSt
ud
yp
op
ula
tio
nT
he
rap
yo
re
xpo
sure
Ou
tco
me
/re
sult
s
Excl
usi
on
scr
ite
ria
incl
ud
ed
the
abse
nce
of
spe
cifi
csy
mp
tom
so
fco
lon
icd
ise
ase
(me
len
a,h
em
ato
che
zia,
dia
rrh
ea,
rele
van
tch
ang
es
inst
oo
lfr
eq
ue
ncy
or
abd
om
inal
pai
n).
Sub
ject
sw
ere
also
exc
lud
ed
ifth
ey
had
pri
or
OC
wit
hin
the
last
5ye
ars,
po
siti
vefa
mily
his
tory
for
CR
C,a
his
tory
of
or
pre
sen
tIB
D,
he
red
itar
yC
RC
syn
dro
me
s,a
bo
dy
we
igh
tg
reat
er
than
15
0kg
or
seve
reca
rdio
vasc
ula
ro
rp
ulm
on
ary
dis
eas
e.
CT
Ch
adlo
wse
nsi
tivi
tyfo
rle
sio
nsB
6m
min
size
,b
ut
de
tect
ion
of
larg
ean
dad
van
ced
lesi
on
s,se
nsi
tivi
tyw
asco
mp
arab
leto
OC
.4
6%
of
sub
ject
sp
refe
rre
dC
TC
,w
hile
37
%p
refe
rre
dO
Cfo
rfu
ture
scre
en
ing
.
Ho
ff,
Ge
ir2
00
9R
CT
1T
he
stu
dy
incl
ud
ed
13
,6
53
sub
ject
sin
the
scre
en
ing
gro
up
(of
wh
ich
on
ly8
,84
6at
ten
de
dsc
ree
nin
g),
and
41
,09
2su
bje
cts
we
rein
the
con
tro
lg
rou
p.
Gro
up
sco
nsi
ste
do
fan
eq
ual
nu
mb
er
of
me
nan
dw
om
en
,ag
ed
55�6
4,
wh
ow
ere
ran
do
mly
sele
cte
dfr
om
2ar
eas
inN
orw
ay;
city
of
Osl
oan
dT
ele
mar
kco
un
ty(u
rban
and
mix
ed
urb
anan
dru
ral
po
pu
lati
on
s).
Th
est
ud
yw
asco
nd
uct
ed
fro
mJa
n.
19
99
toD
ec.
20
00
.
Sig
mo
ido
sco
py
Re
du
ctio
nin
inci
de
nce
of
CR
Cw
ith
fle
xib
lesi
gm
oid
osc
op
ysc
ree
nin
gw
asn
ot
see
naf
ter
7-y
ear
follo
w-u
p.
Mo
rtal
ity
fro
mC
RC
was
no
tsi
gn
ific
antl
yre
du
ced
inth
esc
ree
nin
gg
rou
p.
Joh
nso
n,
C.
Dan
iel
20
08
Cas
ese
rie
sw
ith
ou
tco
ntr
ols
4T
he
stu
dy
incl
ud
ed
2,5
31
asym
pto
mat
icp
atie
nts
,5
0ye
ars
or
old
er
wh
ou
nd
erw
en
tC
TC
follo
we
db
ysa
me
day
colo
no
sco
py
be
twe
en
Feb
.2
00
5an
dD
ec.
20
06
.P
atie
nts
we
ree
xclu
de
dif
the
yp
rese
nte
dan
ysy
mp
tom
so
fC
RC
(an
em
ia,
me
len
a,h
em
ato
che
zia)
mo
reth
ano
nce
inth
ep
ast
6m
on
ths,
ifth
ey
had
IBD
,h
ere
dit
ary
colo
rect
ald
ise
ase
,if
the
yh
adre
ceiv
ed
colo
no
sco
py
inth
ep
ast
5ye
ars
or
had
ap
osi
tive
FOB
Tre
sult
.
CT
Can
dco
lon
osc
op
yC
TC
ide
nti
fie
d9
0%
of
the
ade
no
mas
or
can
cers
me
asu
rin
g1
0m
mo
rm
ore
insu
bje
cts.
Ko
,C
ynth
iaW
.R
etr
osp
ect
ive
cro
ss-s
ect
ion
alst
ud
y
4A
tota
lo
f3
28
,16
7co
lon
osc
op
ies
we
reco
nd
uct
ed
by
12
,91
0p
rovi
de
rs(e
ith
er
gas
tro
en
tero
log
ists
,su
rge
on
s(g
en
era
lo
rco
lore
ctal
)o
rp
rim
ary
care
ph
ysic
ian
Co
lon
osc
op
yG
astr
oe
nte
rolo
gis
tsw
ere
mo
stlik
ely
and
ge
ne
ral
surg
eo
ns
we
rele
ast
like
lyto
de
tect
po
lyp
sd
uri
ng
colo
no
sco
py.
Dia
gn
ost
icb
iop
syra
tes
we
reh
igh
est
for
fam
ilyp
hys
icia
ns
and
low
est
for
colo
rect
alsu
rge
on
s.
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 039
Ta
ble
1(C
on
tin
ued
)
Firs
tau
tho
rD
ate
of
pu
blic
atio
nSt
ud
yd
esi
gn
Leve
lo
fe
vid
en
ceSt
ud
yp
op
ula
tio
nT
he
rap
yo
re
xpo
sure
Ou
tco
me
/re
sult
s
Snar
ep
oly
pe
cto
my
and
po
lyp
rem
ova
lra
tes
we
reh
igh
est
for
gas
tro
en
tero
log
ists
and
low
est
for
fam
ilyp
hys
icia
ns.
Leib
erm
an,
Dav
idA
.2
00
0C
ase
con
tro
l3
Asy
mp
tom
atic
adu
lts
we
rese
lect
ed
fro
m1
3V
ete
ran
sA
ffai
rsm
ed
ical
cen
ters
inth
eU
nit
ed
Stat
es,
be
twe
en
Feb
.1
99
4an
dJa
n.
19
97
.1
7,7
32
pat
ien
tsw
ere
scre
en
ed
for
en
rolm
en
t,3
,19
6w
ere
en
rolle
d;3
,12
1o
fth
ee
nro
lled
pat
ien
ts(9
7.7
%)
un
de
rwe
nt
com
ple
teco
lon
ice
xam
inat
ion
.T
he
me
anag
eo
fth
ep
atie
nts
was
62
.9ye
ars,
and
96
.8%
we
rem
en
.
Co
lon
osc
op
yC
olo
no
sco
py
can
de
tect
adva
nce
dco
lon
icn
eo
pla
sms
inas
ymp
tom
atic
adu
lts
wh
ich
can
no
tb
ed
ete
cte
dw
ith
sig
mo
ido
sco
py.
Man
ser,
Ch
rist
ine
N.
Feb
ruar
y2
01
2N
on
-ra
nd
om
ized
pro
spe
ctiv
eco
ho
rt
21
91
2sc
ree
ne
dan
d2
0,7
74
con
tro
lp
arti
cip
ants
fro
ma
rura
lar
ea
of
Swit
zerl
and
Co
lon
osc
op
yC
olo
no
sco
py
wit
hp
oly
pe
cto
my
sig
nif
ican
tly
red
uce
dC
RC
inci
de
nce
and
can
cer-
rela
ted
mo
rtal
ity
inth
eg
en
era
lp
op
ula
tio
n.
Rab
en
eck
,Li
nd
a2
01
0P
op
ula
tio
n-
bas
ed
pro
spe
ctiv
eco
ho
rt
3T
his
stu
dy
incl
ud
ed
2,4
12
,07
7p
arti
cip
ants
age
db
etw
ee
n5
0an
d9
0(m
ean
age
of
64
)in
On
tari
o,
Can
ada.
Of
the
coh
ort
,8
4.2
%liv
ed
inan
urb
anar
ea,
53
.7%
we
rew
om
en
and
86
.5%
had
aco
-mo
rbid
ity
sco
reo
f0
.Ea
chm
em
be
ro
fth
eco
ho
rtw
asas
sig
ne
dto
1o
f1
3re
gio
ns
bas
ed
on
the
irad
dre
ssin
the
pro
vin
ce.
Pat
ien
tsw
ere
exc
lud
ed
ifth
ey
had
ap
revi
ou
sd
iag
no
sis
of
CR
C,
ulc
era
tive
colit
is,
Cro
hn
’sd
ise
ase
or
had
the
irre
sid
en
cein
the
Sou
thEa
stLo
cal
He
alth
Inte
gra
tio
nN
etw
ork
du
rin
gth
eti
me
of
the
stu
dy.
Co
lon
osc
op
yIn
cre
ase
dco
lon
osc
op
yu
sew
asas
soci
ate
dw
ith
mo
rtal
ity
red
uct
ion
fro
mC
RC
atth
ep
op
ula
tio
nle
vel.
Sin
gh
,H
arm
ind
er
20
10
Po
pu
lati
on
-b
ase
dp
rosp
ect
ive
coh
ort
33
2,3
06
ind
ivid
ual
sfr
om
Man
ito
ba,
On
tari
o,
wh
oh
adn
eg
ativ
ere
sult
so
nin
itia
lco
lon
osc
op
ysc
ree
nin
gb
etw
ee
nA
pr.
1,
19
87
and
Sep
t.3
0,
20
07
.St
ud
yp
op
ula
tio
nin
clu
de
dp
atie
nts
age
db
etw
ee
n5
0an
d8
0.
Ind
ivid
ual
so
uts
ide
this
age
ran
ge
,th
ose
wit
hp
rio
rsi
gm
oid
osc
op
y,IB
D,r
ese
ctiv
eco
lore
ctal
surg
ery
or
CR
Cw
ere
exc
lud
ed
.
Co
lon
osc
op
yT
he
rew
asa
29
%re
du
ctio
nin
ove
rall
CR
Cm
ort
alit
yan
da
47
%re
du
ctio
nin
mo
rtal
ity
fro
md
ista
lC
RC
(SM
R,
bu
tn
ore
du
ctio
nin
mo
rtal
ity
fro
mp
roxi
mal
CR
C)
Th
ere
du
ctio
nin
mo
rtal
ity
fro
md
ista
lC
RC
rem
ain
ed
sig
nif
ican
tfo
rg
reat
er
than
10
year
s
Is Colonoscopy the Method of Choice? Puneet K. Singh
040 Medical Student Research Journal MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Ta
ble
1(C
on
tin
ued
)
Firs
tau
tho
rD
ate
of
pu
blic
atio
nSt
ud
yd
esi
gn
Leve
lo
fe
vid
en
ceSt
ud
yp
op
ula
tio
nT
he
rap
yo
re
xpo
sure
Ou
tco
me
/re
sult
s
Sch
oe
n,
Ro
be
rtE.
20
12
RC
T1
Ato
tal
of
15
4,9
00
me
nan
dw
om
en
age
d5
5�7
4p
arti
cip
ate
din
this
stu
dy
fro
m1
99
3th
rou
gh
20
01
.In
div
idu
als
we
rera
nd
om
lyas
sig
ne
dto
eit
he
ran
inte
rve
nti
on
gro
up
(scr
ee
nin
gw
ith
fle
xib
lesi
gm
oid
osc
op
yw
ith
rep
eat
scre
en
ing
at3�5
year
s)o
rto
the
usu
alca
reg
rou
p.
Sig
mo
ido
sco
py
Inci
de
nce
of
CR
Caf
ter
am
ed
ian
follo
w-u
po
f1
1.9
year
sw
as1
1.9
case
sp
er
10
,00
0p
ers
on
-ye
ars
inth
ein
terv
en
tio
ng
rou
p,
asco
mp
are
dw
ith
15
.2ca
ses
pe
r1
0,0
00
pe
rso
n-y
ear
sin
the
usu
al-c
are
gro
up
.R
ed
uct
ion
sw
ere
see
nin
inci
de
nce
of
CR
Cin
bo
thp
roxi
mal
and
dis
tal
colo
n.
Mo
rtal
ity
was
red
uce
db
y5
0%
on
lyin
dis
tal
CR
Cw
ith
no
chan
ge
inp
roxi
mal
.vo
nW
agn
er,
Ch
rist
ian
20
12
RC
T1
54
7p
atie
nts
wit
hsy
mp
tom
ssu
gg
est
ive
of
CR
Cw
ho
we
rera
nd
om
lyas
sig
ne
dat
ara
tio
of
2:1
tou
nd
erg
oe
ith
er
colo
no
sco
py
(36
2)
or
CT
C(1
85
)O
fth
ese
,3
88
resp
on
de
dto
ap
ost
-te
stq
ue
stio
nn
aire
;21
2w
om
en
(55�8
7ye
ars
old
)an
d1
76
me
n(5
5�9
6ye
ars
old
).3
37
pat
ien
tsre
spo
nd
ed
toth
efo
llow
-up
qu
est
ion
nai
re;1
99
wo
me
n(5
5�8
7ye
ars
old
)an
d1
38
me
n(5
5�9
2ye
ars
old
).
Co
lon
osc
op
yan
dC
TC
Inth
esh
ort
-te
rman
alys
is,p
atie
nts
are
mo
relik
ely
toac
cep
tC
TC
asa
be
tte
rm
eth
od
of
surv
eill
ance
than
colo
no
sco
pie
s.H
ow
eve
r,af
ter
lon
g-t
erm
follo
w-u
p,p
atie
nts
no
ted
that
colo
no
sco
py
off
ere
dso
me
be
ne
fits
Zal
is,
Mic
hae
lE.
20
12
Pro
spe
ctiv
eco
ho
rtw
ith
ou
tco
ntr
ols
46
05
asym
pto
mat
icm
en
and
wo
me
n,
age
d5
0�8
5,
wit
hm
od
era
teto
ave
rag
eri
sko
fC
RC
we
rere
cru
ite
dfr
om
fou
rin
stit
uti
on
s:M
assa
chu
sett
sG
en
era
lH
osp
ital
;B
rig
ham
and
Wo
me
n’s
Ho
spit
al;
Un
ive
rsit
yo
fC
alif
orn
ia,
San
Fran
cisc
oV
ete
ran
sA
ffai
rsM
ed
ical
Ce
nte
r;an
dN
ort
hSh
ore
Me
dic
alC
en
ter,
be
twe
en
Jun
.2
00
5an
dO
ct.
20
10
No
n-c
ath
arti
cC
TC
and
colo
no
sco
py
No
n-c
ath
arti
cC
TC
was
able
toac
cura
tely
de
tect
ade
no
mas
10
mm
or
gre
ate
rb
ut
less
accu
rate
for
smal
ler
lesi
on
sw
he
nco
mp
are
dto
colo
no
sco
py
scre
en
ing
of
sam
eco
ho
rt
RC
T�
ran
do
miz
ed
con
tro
ltr
ials
;C
TC
�co
mp
ute
dto
mo
gra
ph
icco
lon
osc
op
y;O
C�
op
tica
lco
lon
osc
op
y;FS
�fl
exi
ble
sig
mo
ido
sco
py;
FIT
�fe
cal
imm
un
och
em
ical
sto
ol
test
ing
;
FOB
T�
feca
lo
ccu
ltb
loo
dte
stin
g;
CR
C�
colo
rect
alca
nce
r;IB
D�
infl
amm
ato
ryb
ow
el
dis
eas
e.
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 041
was a statistically significant decrease in the hazardof death by 3%.9
Similar results showing significantly decreased CRCincidence and mortality in groups undergoing colono-scopy screening were found in two other population-based prospective studies conducted by Manseret al10, in Switzerland, and by Singh et al11 in Manitoba,Canada. Singh et al11 analyzed a cohort of individualswho had previously undergone CRC screening withonly colonoscopy between April 1984 and September2007 and had received negative results (no polyps/CRC). The overall reduction in CRC mortality within thescreened population of this study was 29%, with thelargest reduction in mortality rates (39%) seen during a5�10 year follow-up, as compared to the generalpopulation.11 Importantly, the study also found therewere differences in the morality rates associated withspecific locations in the colon. There was a statis-tically significant 47% reduction in distal CRC deaths,but no reduction in deaths from proximal CRC.11 Thereduction in mortality due to distal CRC remainedsignificant for up to 10 years following the study’sconclusion.11 A case-control study carried out by Baxteret al12 presented mirroring results, finding that colono-scopy screening not only decreased CRC mortalityin cases vs. controls but also that this screening wasassociated with fewer deaths from left-sided CRC ascompared to right-sided.12
Many recent studies have discovered that discrepan-cies during colonoscopy-specific detection of CRC andprecancerous lesions may be operator dependent.Bretagne et al13 identified that differences in theperformance of 18 endoscopists analyzed in their studyresulted in large ranges of adenoma detection rates(ADR). However, when assessing the detection rate ofactual CRC, these operant-dependent factors did notindependently influence the varied range of rates, aspatient age and sex also played a role.13 Another studyby Adler et al14 went on to identify what it believedwere the specific factors that defined the efficacy andquality of screening by colonoscopists. The moststatistically significant associations, with 41.4% of theinter-physician variability in ADR, were the number ofContinuing Medical Education (CME) meetings eachcolonoscopist attended and the characteristics of theirindividual instruments.14
Some researchers investigated if the specific special-ties of those carrying out colonoscopies played anyrole in the variability of ADR and CRC detection. Baxteret al15 found that although colonoscopy screeningreduced the risk of CRC mortality (regardless of the
specialty of the endoscopist), there was a stronger asso-ciation if a gastroenterologist performed the colono-scopy as opposed to a non-gastroenterologist (e.g., asurgeon or primary care provider). Conclusively, gastro-enterologists provided significantly more protectionfrom CRC death than other providers.15 A study byKo et al16 further identified variability in frequencyof procedures performed by each specific specialty(Fig. 1). Overall, multivariate analysis determined thatnon-gastroenterologists were least likely to detect andremove polyps, and likelihood of diagnostic bio-psy was significantly lower for all surgeons (general/colorectal).16
SigmoidoscopyUnlike colonoscopy, flexible sigmoidoscopy is perfor-
med without sedation, has limited bowel preparationand is thus more often provided by general practi-tioners or non-physicians.1 The use of flexible sigmoi-doscopy CRC screening was analyzed in a Germanobservational study by Graser et al17 and two RCTs: thePLCO trial conducted by Schoen et al18 and the firstof the three Norwegian Colorectal Cancer Prevention(NORCCAP) trials carried out by Hoff et al.19
The PLCO trial mirrored findings presented in manyolder observational trials that showed flexible sigmoi-doscopy conferring protection against CRC mortalityand incidence.8 In this study, a 21% reduction in CRCincidence was observed in the intervention group ascompared to the usual care group, and CRC incidencein specific locations of the colon also showed signifi-cant reductions: 29% in the distal colon and 19% in theproximal.18 Overall, CRC mortality was reduced by 26%in the intervention group as compared to the usual-care group. However, when observing location-specificmortality rates in distal and proximal parts of the colon,the PLCO trial found that distal CRC mortality wasreduced by 50%, but no significant change in mortalitywas observed for proximal CRC (143 and 147 deaths;relative risk, 0.97; 95% CI, 0.77�1.22; P�0.81).18
Compared to the PLCO trial, the NORCAPP trial obser-ved a larger reduction in mortality rates (59%) amongsubjects who took part in sigmoidoscopy screening.19
Nevertheless, like the PLCO trial, some findings ofNORCAPP also substantiated discrepancies in cancermortality rates among discrete locations of the colonwhen sigmoidoscopy was performed. Among the inter-vention group, a greater reduction in both incidenceand mortality (76%) of rectosigmoidal cancer was foundas opposed to CRC.19 Thus, benefits of sigmoidoscopy
Is Colonoscopy the Method of Choice? Puneet K. Singh
042 Medical Student Research Journal MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
were once again shown to be limited to areas of thedistal colon.
The last study analyzing sigmoidoscopy screeningwas a prospective study carried out by Graser et al.17
The sensitivities of five different screening methods:sigmoidoscopy, CTC, colonoscopy, fecal immunochemi-cal stool testing (FIT) and FOBT were all tested inparallel among asymptomatic subjects. Flexible sigmoi-doscopy was 83.3% sensitive for advanced colonicneoplasia (CRC) and only 68% sensitive to adenomas]10 mm. Combining sigmoidoscopy with FOBT or FITenabled an increased detection of large adenomas(76.2 and 71.4%, respectively) as compared to sigmoi-doscopy alone (68%). However, when these tests werecombined for the detection of advanced CRC, noincrease in sensitivity was observed. Although flexiblesigmoidoscopy showed to be a superior test to FOBTand FIT, it was unable to surpass the advanced sen-sitivity of colonoscopy and CTC in detection of CRC andadenomas of all sizes.17
Computed Tomographic ColonographyCTC is a minimally invasive screening tool that is
currently undergoing testing in a number of trials. Likecolonoscopy, CTC provides examination of the entirecolon and rectum; however, it allows for computeri-zed 3D and advanced 2D imaging not available withcolonoscopy.1 In order to compare the efficiency ofCTC to colonoscopy in CRC screening and detection,three observational studies and one UK-based multi-center RCT were analyzed.17,20,21
All three observational studies focused on compar-ing the sensitivity and specificity of CTC in detectingadenomas of various sizes and neoplastic lesions tothat of colonoscopy, with additional comparison toother screening modalities (sigmoidoscopy, FIT andFOBT) completed by Graser et al.17 The study popula-tions assessed in all three studies were comparable andincluded average risk, asymptomatic patients (eachstudy using similar exclusion criteria) who were aged50 or older.17,20,21 All studies presented similar results(Table 2).
Although similarities between the sensitivity andspecificity of CTC and colonoscopy for the detectionof large neoplastic lesions were found, discrepanciesbecame evident in all studies when detecting adeno-mas of smaller sizes, specifically between 5 and 6 mmin diameter (Table 2). All three studies concludedthat CTC was significantly less sensitive for smallerlesions than colonoscopy. Measurements of specificityshowed similar trends.17,20,21 In two of the studies,the median sizes of missed lesions were 7 mm21 and6 mm.20 Graser et al17 found that CTC only missed oneadenoma with advanced histology in the B10 mm sizegroup.
The UK-based RCT carried out by Atkin et al22 pre-sented similar findings to those seen in the observa-tional studies. The sensitivity of CTC to CRC was 85% inthis RCT as compared to 93% with colonoscopy. Still,the most significant discrepancy in CTC screeningpresented by this study was its discovery that a greaternumber of patients assigned to the CTC screening
Figure 1. Variability in rate of polyp detection, biopsy and polyp removal among provider specialty. Gastroenterologists have thehighest rate of polyp detection, polypectomy and polyp removal. General surgeons are least likely to detect polyps, whilecolorectal surgeons have the lowest diagnostic biopsy rate. Family physicians have the highest rate of biopsy, but lowest rate ofpolyp removal. (Modified from Ko et al.16)
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 043
group needed to undergo additional colonic inves-tigations (after initial screening) as compared to thecolonoscopy group (30.0% vs. 8.2%).22 Within the colo-noscopy group, the major reason for additional screen-ing was incomplete colonoscopy (did not reach thececum) as seen in 11.3% of patients. In contrast, themajor causes for additional CTC investigations werelow predictive value for CRC or polyps ]10 mm(15.6%) and failure to confirm the presence of small(B10 mm) polyps (9.2%). In both cases, the additionalinvestigation was a new or repeat colonoscopy; a moreinvasive procedure than CTC. Finally, this RCT was theonly study to identify a statistically significant differ-ence in men and women with regard to the need foradditional investigations after screening. Men were sixtimes more likely to need further investigation afterCTC compared to colonoscopy, while women wereonly two times more likely.22
Patient Experience, Education and CompliancePatient experiences, perspectives on CRC screening
and compliance to screening guidelines were alsoanalyzed. Research conducted by von Wagner et al23
found that individuals undergoing colonoscopy weresignificantly less satisfied, more worried, experiencedmore physical discomfort and reported more adverseeffects such as ‘feeling faint or dizzy’ than those takingpart in CTC screening. This study further noted thatpatients had a better experience with CTC screeningthan with colonoscopy.17,20�22 However, this initialdissatisfaction with colonoscopy was not absolute, asvon Wagner et al23 identified that patients undergoingCTC had a greater number of post-procedure referralrates as compared to those who took part in colono-scopy screening (33% vs. 7%). Thus, the study con-cluded that after 3 months, patients reported greatersatisfaction with the long-term outcomes of their colo-noscopy screening compared to CTC23; a result alsofound by Atkin et al.22
It is likely that because the overall benefits of colo-
noscopy are not known by patients initially, the nega-
tive connotations surrounding CRC screening are factors
that deter patients from actually fulfilling screening
guidelines. A RCT conducted by de Wijkerslooth et al24
examined the reasons for participation and non-
participation in CRC screening among a study popula-
tion who had never undergone screening in two
regions of the Netherlands. This study found that the
most significant reason to participate in CRC screening
(either colonoscopy or CTC) was ‘it allows early detec-
tion of precursor lesions’ (the most decisive reason in
both screening modalities; 72% for colonoscopy vs.
68% for CTC).24 The most significant reason for non-
participation with respect to colonoscopy was ‘the
examination strikes me as unpleasant’ (66%) while for
CTC the reasons were both lack of time and absence of
symptoms.24 A second RCT looked at the ‘expected’
burden of screening before colonoscopy or CTC and
compared it to the actual (‘perceived’) burden experi-
enced during either procedure.25 This research discov-
ered that although participants expected colonoscopy
to be more burdensome than CTC, in reality they
experienced significantly more overall burden with CTC
(79% with colonoscopy vs. 82% with CTC).25
Many of the reasons mentioned for and against
screening participation stem from a lack of patient
knowledge about CRC and its prevention, and most
importantly from a lack of doctor�patient communica-
tion about specific guidelines for screening. A case
series by Courtney et al26 identified that within their
study population, only 63% of the cohort had ever
received any sort of CRC screening (FOBT/ sigmoido-
scopy or colonoscopy), with the majority of this subset
being ‘potentially high risk’ participants (84%). Overall,
individuals significantly more likely to have received
testing were those who were either between the ages
of 65 and 74, had at some point received screening
Table 2. Differences in sensitivity and specificity of CTC and colonoscopy in detecting adenomatous lesions of various sizes
CTC (large lesions; �10 mm)CTC vs. Colonoscopy
(small lesions; 5�6 mm)
Study Sensitivity (%) Specificity Sensitivity (%)
Graser et al17 96.7 n/a 59.2 94.6Johnson et al20 90 86% 78 100Zalis et al20 91 85% 59 76
Colonoscopy and CTC have similar efficacy in detecting large lesions; however, colonoscopy is significantly more sensitive than CTC for smaller
lesions.
Is Colonoscopy the Method of Choice? Puneet K. Singh
044 Medical Student Research Journal MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
advice from their family physician or had discussedfamily history of CRC with their doctor.26
Similar results permeated from a prospective studyby Fenton et al27 which took a deeper look at what agroup of physicians actually discussed with patientsduring visits. In 76% of the interactions, physiciansdiscussed CRC screening for a median time of 2.5 min.Physicians described one or two modalities for screen-ing, with colonoscopy always being mentioned. Doctorsdiscussed benefits of CRC screening in more than halfof the encounters, but less often commented on risks/susceptibility to CRC, barriers to screening, or self-efficacy of screening. After all visits were complete, itwas found that patients in the discussion group had asignificantly increased knowledge of risk/susceptibilityto CRC and had an increased intention to undergoscreening. Unfortunately, there was no significant changein perceived benefits of screening, barriers or self-efficacy in this discussion group compared to whenthey initially began the visit. Finally, a 6-month follow-up revealed that 45% of patients within the group thatdiscussed CRC screening actually underwent screening,as compared to the non-discussion group in which nopatient was screened.27
DISCUSSIONScreening for CRC is an integral part of cancer
prevention and has the capacity to positively impactCRC mortality rates. Colonoscopy has proven to be aleading method of CRC screening and its use hasincreased in many regions across North America.9,11
However, detection of CRC via colonoscopy does notoccur uniformly within the colon, and specific ‘burdens’of screening are discouraging individuals from partici-pating in colonoscopy. Thus, prematurely acceptingcolonoscopy to be the superior screening modality iserroneous. Many factors must be considered whendefining a tool as superior including patient prefer-ences, user-dependent skills, success of CRC detectionand cost-effectiveness. Until research can address thesefactors and clearly define superiority, the debate overwhich method to choose for CRC screening remains.
Unlike research on sigmoidoscopy and CTC, currentscholarly literature analyzed in this study has notproduced RCTs studying colonoscopy as a methodof CRC screening. Many of the colonoscopy-focusedstudies analyzed in this review were observational(level 4) studies � a major limitation of this paper.Some studies lacked control groups, and their cohortswere often too small. In addition, each study focused
on only one or two screening modalities at a time, thuspreventing grouped analysis of common variables. Theinitiation of RCTs with large cohorts comparing eachspecific modality in parallel and with more universaldata analysis techniques is necessary. In addition, moreprospective studies looking at the long-term benefitsof colonoscopy are needed as current research showsmany of the benefits of colonoscopy are observedseveral years following the initial procedure.11 However,to accurately determine long-term benefits, studiesmust also focus on populations closer to the age of50 as loss to follow-up due to death can negativelyimpact results.
Other limitations of this review included restrictingsearch strategies with the filter ‘full text available’ dur-ing data collection and also focusing on only a selectgroup of screening modalities. Studies on FOBT orFIT could have expanded the scope of this paper andenabled a more comprehensive comparison of allscreening tools recommended by current guidelines.
Nevertheless, this paper addresses several importantaspects of colonoscopy screening. First, a number ofproblems still remain in the actual effectiveness ofcolonoscopy screening. Many articles determined thatcolonoscopy was more beneficial in detecting distalCRC as opposed to proximal. Two RCTs identified thatsigmoidoscopy also presented with similar caveats.18,19
Although both screening tools were limited in thelocation they could optimally perform, sigmoidoscopyproved to cause a greater reduction in distal CRCmortality as compared to colonoscopy. The PLCOtrial found that mortality was reduced by 50% in thedistal colon using sigmoidoscopy compared to colono-scopy,18 while the NORCAPP trial also identified thatsigmoidoscopy’s greatest reduction of mortality (76%)was seen for rectosigmoidal cancer (specific to thedistal colon).19 Both values were higher than the 47%reduction in distal CRC mortality found via colono-scopy.11 Identifying ways to optimize screening of boththe proximal and distal colon is therefore necessaryto enable colonoscopy to surpass the strengths ofsigmoidoscopy.
Another major issue associated with colonoscopywas the variations in results due to the level of exper-tise of each colonoscopist. Gastroenterologists provedto be the most efficient when compared to surgeonsand primary care physicians (Table 2). These perfor-mance differences can greatly impact the accuratedetection of CRC and precancerous lesions. Further-more, these differences in expertise may prevent the
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 045
significantly at-risk populations from being screenedby the most skilled provider. Individuals from higher-income households (�$70,000 compared to 5$39,999)26
are more likely to take part in CRC screening, as aspecialist appointment is more costly than a primarycare visit. This is an unfortunate fact considering lowincome is a significant risk factor for CRC mortality.9 It isimperative that all health care professionals performingcolonoscopies attain standardized training and con-tinually strive to advance their skills so every patientcan receive screening from an equally qualified colo-noscopist. One way in doing so may be to increaseattendance at CME meetings, as this had a positiveassociation with ADR in primary care providers.14
In spite of the disadvantages of colonoscopy use,this screening modality is still the most sensitive andspecific test for detecting CRC and precancerouslesions of all sizes. Studies comparing colonoscopy toCTC and sigmoidoscopy identified that the rank fromhighest to lowest for specificity and sensitivity wascolonoscopy �CTC �sigmoidoscopy. Although CTCwas the closest to colonoscopy in sensitivity and speci-ficity for CRC, it was 20�30% less sensitive for lesionsB6 mm in size than colonoscopy. Thus, exclusive useof CTC over colonoscopy risks missing small lesionsthat can present similar threats of cancerous growthas large ones. As many articles have noted, this failureto detect small lesions forces patients to endure addi-tional investigations via colonoscopy in order toidentify all those that are missed. Patients thus becomeburdened with extra tests leading to unnecessarystress and worry.
Currently only 65.1% of the US population is up-to-date on screening for CRC as recommended bystandard guidelines.7 Among studied populations, themajor reason for participation in both colonoscopy andCTC was to identify precancerous lesions, while themain reason to not participate was the thought thatthe colonoscopy procedure would be unpleasant andthe belief that a lack of symptoms did not warrantundergoing CTC. Furthermore, when looking at rea-sons to choose specific screening modalities patientsalso assumed colonoscopy screening to be more bur-densome than CTC due to its preparation and un-pleasantness. However, patients admitted that in thelong run colonoscopy was less burdensome,25 suggest-ing that patient expectations or beliefs may often bedue to a lack of knowledge and guidance. Under-standing the factors that shape a patient’s views onCRC screening is essential in learning how to present
screening in a positive light and how to createeducational material that may further empower pa-tients to comply with guidelines.
Much research has shown that the most significantfactor in promoting screening is the interaction be-tween a physician and patient. In one study, discus-sions about the risks and benefits of CRC, options forscreening and family history of CRC occurred in only76% of patient�doctor meetings.27 Nevertheless, ofthe group of patients whose physicians did make anattempt to provide educational information, 45% wenton to take part in colonoscopy screening. This studyhighlighted the fact that a simple conversation canenable individuals to take action. If physicians takeadequate time to have detailed discussions with all at-risk patients and eliminate any myths of the procedure,it is likely that participation in colonoscopy screeningwill significantly increase.
CONCLUSIONIn conclusion, colonoscopy has proven to be the
most sensitive and specific tool for CRC screening andhas allowed for significant reductions in CRC incidenceand mortality. In order to ascertain that colonoscopy issuperior to sigmoidoscopy and CTC in all aspects ofCRC such as effectiveness in detecting both distal andproximal CRC, convenience of screening, efficiency ofscreening and patient preference, a number of factorsmust be addressed. First, large-scale RCTs looking atall three screening modalities together must beinitiated in order to understand the exclusive benefitsof colonoscopy and to move away from observationalstudies that are clouding current research. Next,eliminating the weakness of colonoscopy in detectingproximal CRC is imperative in order to ensure that itprovides the greatest advantage possible. In addition,in order to enable patients to understand the lifesaving benefits of colonoscopy, misconceptions andnarrowed views about this modality must be thor-oughly addressed. Empowerment can start within thedoctor�patient relationship. Once patients become moreaware of their health and more knowledgeable aboutall of the preventative procedures available to maintaintheir wellbeing, they may be more inclined to takeaction. Finally, performing colonoscopies must becomea more standardized procedure. All colonoscopistsshould ideally learn the same techniques and haveaccess to the same quality of screening tools to ensurethat operant-dependent differences do not confoundthe results of colonoscopy screening.
Is Colonoscopy the Method of Choice? Puneet K. Singh
046 Medical Student Research Journal MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Conflict of interest and funding: The author declares noconflict of interest.
REFERENCES1. Holt PR, Kozuch P, Mewar S. Colon cancer and the elderly:
from screening to treatment in management of GI disease
in the elderly. Best Pract Res Clin Gastroenterol 2009; 23:
889�907. doi: 10.1016/j.bpg.2009.10.0102. Siegel R, Naishadham D, Jemal A. Cancer statistics, 2012.
CA Cancer J Clin 2012; 62: 10�29. doi: 10.3322/caac.201383. Manne U, Shanmugam C, Katkoori VR, Bumpers HL, Grizzle
WE. Development and progression of colorectal neoplasia.
Cancer Biomark 2010; 9: 235�65. doi: 10.3233/CBM-2011-01604. Qaseem A, Denberg TD, Hopkins RH, Jr., et al. Screening
for colorectal cancer: a guidance statement from the
American College of Physicians. Ann Intern Med 2012; 156:
378�86. doi: 10.7326/0003-4819-156-5-201203060-000105. Centers for Disease Control and Prevention. Vital signs: colo-
rectal cancer screening, incidence, and mortality�United States,
2002�2010. MMWR Morb Mortal Wkly Rep 2011; 60: 884�9.6. Lieberman D. Colorectal cancer screening: practice guide-
lines. Dig Dis 2012; 30(Suppl 2): 34�8. doi: 10.1159/0003418917. Centers for Disease Control and Prevention. Vital signs:
colorectal cancer screening test use � United States, 2012.
MMWR Morb Mortal Wkly Rep 2013; 62: 881�8.8. Kahi CJ, Anderson JC, Rex DK. Screening and surveillance
for colorectal cancer: state of the art. Gastrointest Endosc
2013; 77: 335�50. doi: 10.1016/j.gie.2013.01.0029. Rabeneck L, Paszat LF, Saskin R, Stukel TA. Association between
colonoscopy rates and colorectal cancer mortality. Am J
Gastroenterol 2010; 105: 1627�32. doi: 10.1038/ajg.2010.8310. Manser CN, Bachmann LM, Brunner J, Hunold F, Bauerfeind P,
Marbet UA. Colonoscopy screening markedly reduces the
occurrence of colon carcinomas and carcinoma-related death: a
closed cohort study. Gastrointest Endosc 2012; 76: 110�17.
doi: 10.1016/j.gie.2012.02.04011. Singh H, Nugent Z, Demers AA, Kliewer EV, Mahmud SM,
Bernstein CN. The reduction in colorectal cancer mortality
after colonoscopy varies by site of the cancer. Gastroenter-
ology 2010; 139: 1128�37. doi: 10.1053/j.gastro.2010.06.05212. Baxter NN, Goldwasser MA, Paszat LF, Saskin R, Urbach
DR, Rabeneck L. Association of colonoscopy and death from
colorectal cancer. Ann Intern Med 2009; 1501�813. Bretagne JF, Hamonic S, Piette C, et al. Variations between
endoscopists in rates of detection of colorectal neoplasia and
their impact on a regional screening program based on colono-
scopy after fecal occult blood testing. Gastrointest Endosc 2010;
71: 335�41. doi: 10.1016/j.gie.2009.08.03214. Adler A, Wegscheider K, Lieberman D, et al. Factors deter-
mining the quality of screening colonoscopy: a prospective
study on adenoma detection rates, from 12,134 examinations
(Berlin colonoscopy project 3, BECOP-3). Gut 2013; 62: 236�41.
doi: 10.1136/gutjnl-2011-30016715. Baxter NN, Warren JL, Barrett MJ, Stukel TA, Doria-Rose
VP. Association between colonoscopy and colorectal cancer
mortality in a US cohort according to site of cancer andcolonoscopist specialty. J Clin Oncol 2012; 30: 2664�9.doi: 10.1200/JCO.2011.40.477216. Ko CW, Dominitz JA, Green P, Kreuter W, Baldwin LM.Specialty differences in polyp detection, removal, and biopsyduring colonoscopy. Am J Med 2010; 123: 528�35.doi: 10.1016/j.amjmed.2010.01.01617. Graser A, Stieber P, Nagel D, et al. Comparison of CTcolonography, colonoscopy, sigmoidoscopy and faecal occultblood tests for the detection of advanced adenoma in anaverage risk population. Gut 2009; 58: 241�8. doi: 10.1136/gut.2008.15644818. Schoen RE, Pinsky PF, Weissfeld JL, et al. Colorectal-cancerincidence and mortality with screening flexible sigmoido-scopy. N Engl J Med 2012; 366: 2345�57. doi: 10.1056/NEJMoa111463519. Hoff G, Grotmol T, Skovlund E, Bretthauer M, NorwegianColorectal Cancer Prevention Study G. Risk of colorectal cancerseven years after flexible sigmoidoscopy screening: randomisedcontrolled trial. BMJ 2009; 338: b1846. doi: 10.1136/bmj.b184620. Johnson CD, Chen MH, Toledano AY, et al. Accuracy of CTcolonography for detection of large adenomas and cancers. NEngl J Med 2008; 359: 1207�17. doi: 10.1056/NEJMoa080099621. Zalis ME, Blake MA, Cai W, et al. Diagnostic accuracyof laxative-free computed tomographic colonography fordetection of adenomatous polyps in asymptomatic adults:a prospective evaluation. Ann Intern Med 2012; 156: 692�702.doi: 10.7326/0003-4819-156-10-201205150-0000522. Atkin W, Dadswell E, Wooldrage K, et al. Computedtomographic colonography versus colonoscopy for investi-gation of patients with symptoms suggestive of colorectalcancer (SIGGAR): a multicentre randomised trial. Lancet 2013;381: 1194�202. doi: 10.1016/S0140-6736(12)62186-223. von Wagner C, Ghanouni A, Halligan S, et al. Patientacceptability and psychologic consequences of CT colonographycompared with those of colonoscopy: results from a multicenterrandomized controlled trial of symptomatic patients. Radiology2012; 263: 723�31. doi: 10.1148/radiol.1211152324. de Wijkerslooth TR, de Haan MC, Stoop EM, et al. Reasons forparticipation and nonparticipation in colorectal cancer screening:a randomized trial of colonoscopy and CT colonography. Am JGastroenterol 2012; 107: 1777�83. doi: 10.1038/ajg.201225. de Wijkerslooth TR, de Haan MC, Stoop EM, et al. Burdenof colonoscopy compared to non-cathartic CT-colonographyin a colorectal cancer screening programme: randomisedcontrolled trial. Gut 2012; 61: 1552�9. doi: 10.1038/ajg.201226. Courtney RJ, Paul CL, Sanson-Fisher RW, et al. Individual- andprovider-level factors associated with colorectal cancer screeningin accordance with guideline recommendation:a community-level perspective across varying levels of risk. BMCPublic Health 2013; 13: 248. doi: 10.1186/1471-2458-13-24827. Fenton JJ, Jerant AF, von Friederichs-Fitzwater MM,Tancredi DJ, Franks P Physician counseling for colorectalcancer screening: impact on patient attitudes, beliefs, andbehavior. J Am Board Fam Med 2011; 24: 673�81. doi:10.3122/jabfm.2011.06.110001
Puneet K. Singh Is Colonoscopy the Method of Choice?
MSRJ # 2014 VOL: 04. Issue: Fall
epub September 2014; www.msrj.org
Medical Student Research Journal 047