The Latest in Screening and Over-diagnosis

8/20/2019 The Latest in Screening and Over-diagnosis

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The Promise and Pitfalls

of Cancer Screening

Jennifer Croswell, MD, MPHMedical Officer, Center for Evidence and Practice Improvement

genc! for Healthcare "esearch and #$alit!

%&S& Department of Health and H$man Services


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Disclaimer

• This tal' does not represent the official position of

the genc! for Healthcare "esearch and #$alit!

• Tho$ghts presented are m! opinions alone


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P$(lic Messages (o$t Screening

re %(i)$ito$s and Int$itivel! Powerf$l


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How Do Preventive Medicine Specialists

pproach Screening Tests*

“All screening programs do harm; some do good as well.”--Sir Muir Gray, former Director, ! "ational Screening #ommittee

“$ %elie&e that one can simplify a message so much that

one is lying.” +Dr& Otis rawle!, Chief Medical Officer, CS

'ager resident( “A well person is a patient who has

not %een sufficiently screened yet.”

*From CK Meador. “The Last Well Person.” NEJM. 1994.

Attending physician( “)hat is a well person*”


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How Do Preventive Medicine Specialists pproach

Screening Tests*

-h! the difference in viewpoint*

.& few new aphorisms to help !o$ appreciate the

$ncertainties and co$nterint$itive nat$re of cancer

screening


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It/s Hard to Ma'e Health! People etter Off Than

The! lread! re

• Screening and treatment are different

activities that target different pop$lations0

– Treatment intervenes on s!mptomatic people

with active pro(lems see'ing help

– Screening intervenes on as!mptomatic people witho$t 'nown iss$es


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It/s Hard to Ma'e Health! People etter Off Than

The! lread! re

• The practical implication*

–

Most people ne&er get the cancer in +uestion – These fol's cannot 1(! definition2 (enefit

–

The! are still e3posed to an! potentialassociated harms


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• Screening is li'e a lotter!0

–Man! participate, ($t winning 1e&g&,

avoiding a death from a cancer d$e to earl!

detection2 is relativel! rare

–$t something is missing from this

analog!.&

Screening


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There/s 4o 5ree 6$nch

• Screening is a pacage or cascade of activities0

– If !o$ (enefit, it is d$e to0

Screening Test 7 Diagnostic Confirmation 7 Treatment

–People ma'e this connection int$itivel!

18That mammogram saved m! life9:2, ($t.

–There is a fre)$ent disconnect that the potential also

e3ists for harm at an! of these points 18It/s

;$st a (lood test


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How I 6earned to Stop ss$mingand 6ove the Scientific Method


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• People 8pa! to pla!: more than the! see a ret$rn

• However, the (enefits and harms are different 0

– enefits0 "ed$ctions in mor(idit! of treatment and death

– Harms0 5alse positives, complications of diagnostic testing

and treatment, overdiagnosis, financial


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Sooner Is 4ot $tomaticall! etter

• Man! arg$ments for screening are made on the

(asis of0

– The difference in s$rvival rates (etween local and

advanced cancer


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6ead=Time ias

Symptom Onset

Sreendetet!on

Lead"

t!me

#eath$!rth


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Mis$se of >=?ear S$rvival "ates

1@ Snidel! -hiplash S!ndrome2

*Analogy credit: Dr. Barry Kramer, NCI


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(asis of0

– The difference in s$rvival rates (etween local and

advanced cancer

– The fact that some pop$lations 1e&g&, !o$nger

people or people of color2 have more aggressive

cancers, and so necessaril! stand to (enefit morefrom earlier detection 1and so screening sho$ld start

earlier and (e done more often in these individ$als2


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6ength=iased Sampling,

Or 8Stac'ing the Dec':


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T!me

S ! % e o & a n e r

S!%e 'hen aner a(sessymptoms

S!%e 'hen aner a(ses

death

The Aoldiloc's Principle

14ot Too 5ast, 4ot Too Slow, $t J$st "ight2

Screening will preerentiallydetect Cancer! grow too

a!t or !creening

to "elp


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More Is 4ot lwa!s etter


(asis of0

– The ($rden of the disease

186oo' how man! people die ever! !ear&:2


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“he "ational #ancer $nstitute is conducting arandomied trial to determine whether or not

screening reduces prostate cancer mortality,

%ut it will tae si/teen years. 0alf a millionmen will die of prostate cancer %efore this

study is completed, and it is unrealistic to

e/pect clinicians to refrain from using 1SA inthe meantime.” 1B2


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(asis of0



– How sensitive the technolog! is

186oo' how m$ch we can find9:2


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(asis of0



– How sensitive the technolog! is

186oo' how m$ch we can find9:2

• These are prere+uisites of a s$ccessf$l screening

program, ($t not proof of its effectiveness


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• The point of screening is to red$ce s$ffering and

death, not ;$st to find as m$ch cancer as possi(le


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The More -e 6oo', The More -e 5ind

• -e can loo' so hard we find things we didn/t need

to

• This is called overdiagnosis0 – Diagnosing disease that wo$ld never have harmed the

person, or even (een detected in the a(sence of

screening

– -e can/t tell if indi&iduals are overdiagnosed

– $t we can see the phenomenon in st$dies


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The More -e 6oo', The More -e 5ind

1E3ample0 Prostate Cancer2

)

)

1))

1)

+))

+),e' Cases

Mortal!ty

-/0 , e '

a s e s o r d e a t h p e r 1

) ) )

) ) m e n

Data from "#$2s Sur&eillance, 'pidemiology, and 'nd 3esults 1rogram

Th A ldil ' P i i l


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T!me

S ! % e o & a n e r

S!%e 'hen aner a(sessymptoms

S!%e 'hen aner a(ses

death

#$erdiagno!ed cancer!

The Aoldiloc's Principle

14ot Too 5ast, 4ot Too Slow, $t J$st "ight2

Screening willma%e adi&erenceCancer! grow too

a!t or !creening

to "elp


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fter Clara Haignere.was diagnosed with DCIS after a mammogram.she wasnt too

worried& One of her ph!sicians called it a Fhalf=assF cancer.&&

She intended to 'eep a watchf$l e!e on Git, ($t then her grown son sat in on a meeting in

which her doctor reco$nted the stor! of a patient who didnt get treated and had ametastasis.&The message was clear0 6et this (e, and !o$ co$ld (e dead& FIm a widow,

and so m! son lost his dad,F Haignere told me& 8.&So how do !o$ sa! no*F .&She

agreed to $ndergo a l$mpectom!& FThere's a cascade that pulls you down this slope,F

she sa!s& "They just say, ‘We'll just do one more thing and be done with it,' but

that's not what happens."

Haigneres first s$rger! led to a second.and then a third, after s$rgeons failed to remove

the lesions.cleanl!.&Event$all!, she ended $p with a mastectom!.&Doctors tell her

she has ver! little ris' of rec$rrence, ($t she sa!s, FI lost m! left (reast&:

She lost a (reast and si3 months of wor', Ffor stage ero cancer that pro(a(l! wo$ldnt

have 'illed me&F


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Screening/s Positive 5eed(ac' 6oop

1@ Things Snow(all2

Increasedscreening

Lo'er threshold

o& detet!on2e.3. moresens!t!e

tehnolo3!es5 M!lderspetr(mo& d!sease

/pparent!mproement

!n d!seaseo(tomes

6!3herd!sease

detet!on

rate

/pparent!nrease !n

d!seaseprealene

4rom 5lac, )elch. A63. 7889.


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Ta'e=wa!s

• Sreen!n3 !s a omple7 o(nter!nt(!t!e !nterent!on

• O(r d!ret o8serat!ons o&ten lead (s astray

• We need to 'ath o(t &or o(r ass(mpt!ons and loo toh!3h":(al!ty e!dene to (nderstand the e;et!eness

o& d!;erent sreen!n3 pro3rams•

p(8l! health messa3!n3 m(st allo' !nd!!d(als to(nderstand these trade"o;s and mae the!r de!s!ons8ased on a(rate and omplete !n&ormat!on


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