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LETTER TO THE EDITOR
Early Impact of Mammographic Screening in WesternSiberia
To the Editor:
In most countries nowadays, breast cancer is the
most common cancer in the female population. As in
most cancers, there is a strong association of the stage
disease with both overall and free-disease survival
after adequate treatment. Thus, early diagnosis of
these tumors has strong potential to decrease mortal-
ity from the disease. In the randomized trials, a signifi-
cant 20% decrease in breast cancer mortality was
observed among all invited to screening (attendees and
nonattendees). The reduction is likely to be of the
order of 30% among women who underwent
mammography screening regularly (2,3,5).
In Khanty-Mansiysky Autonomous Okrug – Ugra,
Russian Federation, breast cancer is the most common
cancer tumor among female population during the last
10 years. In 2007 the Breast Cancer Screening Pro-
gram (BCSP) was implemented in Ugra (6). The BCSP
in Ugra covers the female population aged over
40 years, with two-view mammography examination
(MLO and CC). The screening interval is 2 years, and
single reading is the standard. Data on screening are
obtained every year from the annual reports for the
State Healthcare Department. The form for that
annual report has been created by the authors for the
BCSP. The information on the female population, all
newly diagnosed breast cancer cases and deaths due to
breast cancer in Ugra was obtained from State Cancer
Registry for the period 2002–2011. Statistical analysiswas carried out using Poisson regression, on four
endpoints in turn: breast cancer incidence, breast can-
cer mortality, incidence of node positive breast cancer
and incidence of invasive breast cancers of size greater
than 20 mm. We tested for a significant difference in
average incidence between the prescreening years
(2002–2006) and the screening (2007–2011), adjustingfor the trend in the prescreening years, and for a
change in the trend between prescreening and screen-
ing years. We also calculated the expected values for
the four endpoints based on the trends in the presc-
reening years, and compared these with the observed
values.
Overall, 56.2% of the target population (186,460)
has been screened at least once. 460 breast cancer
cases were diagnosed within the first round and 22
cases during the second round of screening. Incidence
of cancers was increasing in the prescreening years and
continued to do so at the same rate in the screening.
There was no significant difference in average inci-
dence between the two screening periods (p = 0.1) or
any change in the trend between the pre and postsc-
reening periods (p = 0.6). There was a significant
change in the trend in incidence of node positive dis-
ease (p = 0.007) between the prescreening and screen-
ing periods, with an increasing trend in the
prescreening period which was no longer present in the
screening years (Fig. 1). Based on the prescreening
trend, the expected number of node positive cancers in
the screening period was 1,197, whereas the observed
number was 848, a deficit of 29%. The corresponding
results for incidence of cancers of size greater than
20 mm shows a reduction in the average incidence of
tumors >20 mm in the screening period, taking
account of the trend in the prescreening, of borderline
significance (p = 0.06). There were 1,240 such cancers
in the screening period compared with 1,595 expected,
a reduction of 24%. The estimation of the observed
and expected breast cancer deaths from the trend in
mortality up to 2006 indicates a reduction in deaths in
the screening period, taking account of the prescreen-
ing trend. The difference was not significant (p = 0.9),
nor was there a significant change in the trend in the
screening period (p = 0.3). There were 542 breast can-
cer deaths in years 2007–2011 compared with 614
expected, a nonsignificant 12% reduction.
Our results indicate that the incidence of node posi-
tive breast cancer has declined significantly following
Address correspondence and reprint requests to: Professor Natalia
Zakharova, PhD, MD, Department of Oncology and Radiology,
Khanty-Mansiysk State Medical Academy, Mira 40, Khanty-Mansiysky Auton-
omous Okrug–Ugra, Khanty-Mansiysk 628012, Russian Federation, or
e-mails: [email protected] and [email protected]
DOI: 10.1111/tbj.12248
© 2014 Wiley Periodicals, Inc., 1075-122X/14The Breast Journal, Volume 20 Number 2, 2014 219–220
the introduction of mammographic screening in Khan-
ty-Mansiysky Autonomous Okrug. There was a bor-
derline significant reduction in rates of invasive
tumors of size greater than 20 mm. The reductions in
node positive and large tumors are consistent with the
findings of the Swedish organized Screening Evalua-
tion Group (7). No significant reduction in breast can-
cer mortality has been observed, which is to be
expected in the first 5 years of the program. Most of
the deaths from breast cancer in the first 5 years will
be from cancer diagnosed before the screening started
(5). The reduction in node positive disease, however,
suggests that a significant mortality reduction will be
observed in the future. In the randomized trials of
breast screening, the reductions in node positive can-
cer incidence closely approximated the reductions in
breast cancer mortality (1,3). We found no significant
increase in incidence with the introduction of screen-
ing. This suggests that there is no substantial overdiag-
nosis in this program.
In terms of research, the main target for the future
is further observation of breast cancer incidence and
mortality. In addition, more detailed analysis is indi-
cated of the individual cancers, in terms of screening/
symptomatic status, prognostic features, and mortal-
ity. It should be noted that this work is aimed not at
the efficacy of screening in principle, which is a matter
for the trials, but at evaluation of this particular
screening program. In clinical terms, since the findings
to date suggest a benefit of the screening, the main
aim should be to improve coverage of the population
with screening.
In conclusion, mammographic screening in Khanty-
Mansiysky Autonomous Okrug has been associated
with a significant reduction in node positive breast
cancers, taking account of prescreening trends. It is
likely that a corresponding significant mortality reduc-
tion will emerge in the future. Careful follow-up of
the population should continue.
Natalia Zakharova, PhD, MD*
Stephen Duffy, MSc†
*Department of Oncology and Radiology
State Khanty-Mansiysk Medical Academy
Khanty-Mansiysk
Russian Federation
and †Centre for Cancer Prevention
Wolfson Institute of Preventive Medicine
Barts and The London School of Medicine and Dentistry
Queen Mary University of London
London
UK
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Figure 1. Observed incidence of node positive breast cancer in
Ugra, ages 40 +, and incidence expected on the basis of the trend
in 2002–2006.
220 • letter to the editor