Colorectal cancer screening results in the regions of Kazakhstan with different levels of cancer prevalence.

Abstract

62 Background: In Kazakhstan colorectal cancer (CRC) occupies the third position in the structure of total oncological incidence and mortality. Kazakhstan is a country with a large territory, with different geographical, industrial characteristics and dietary habits of the population. So CRC prevalence levels vary from region to region: in 2013 the highest regional incidence rate is 6 times higher than the lowest. CRC population screening among men and women aged 50-70 years was started in 2011 in Kazakhstan. Methods: Within 10 years of the screening, 9 532 927 men and women were examined, 3419 CRC cases were detected. Coverage of target population ranged from 78.4% in 2012 to 53.1% in 2020. The analysis of screening indicators was carried out: cancer detection rate, the proportion of 0-1 stages, the ratio to the underlying incidence, the relationship with the dynamics of CRC incidence and mortality. According to the incidence rate in 2011-2020 regions of the country are conditionally divided into three groups: group A – high level (31.04-23.5 per 100 thousand population), group B – medium level (20.5-15.0%ooo), C - low level (11.6- 8.1%ooo). Results: The average annual CRC detection rate for 10 years of screening was 0.4% (4 cancer cases per 1000 examined), in groups A - 0.5%, B - 0.4% and C - 0.3%. The detection ratio of stage 0-I was 0.08%: in groups A - 0.10%, B - 0.09% and C - 0.05%. The average annual incidence rates were in groups A - 27.2 per 100 thousand population, B - 18.7%ooo and C - 9.8%ooo. During time of g-FOBT applying (2011-2013), the average annual incidence rates in the groups were in groups: A - 25.8%ooo, B - 16.4%ooo, C - 8.2%ooo. During time of using FIT (i-FOBT, 2014-2020), the average annual incidence rates increased to 27.0%ooo, 20.0%ooo and 9.9%ooo respectively. The greatest increase in the incidence was noted in groups B and C (22.7% and 22.2%), the smallest in group A (4.7%). Screening increased the CRC incidence from 15.5%ooo in 2011 to 16.5%ooo in 2020 and reduced mortality from 9.3%ooo (2011) to 8.0%ooo (2020). Conclusions: Screening increased the incidence (6.5%) and decreased the mortality from CRC (14%) for 10 years in Kazakhstan. There is a particularly significant effect of screening on the growth of some indicators (incidence and mortality rates, cancer detection rate and early cancer detection) in regions with a low CRC prevalence.