Breast Cancer in Kazakhstan, 2004-2023: Successful Mortality Reduction Driven by Organized Screening and Stage Shift

To quantify two-decade national trends in the breast cancer burden in Kazakhstan and evaluate the performance of the organized mammography screening programme-including stage distribution and regional heterogeneity after its scale-up.

We conducted a retrospective, population-based evaluation using national registry and screening data. Population indicators (incidence, mortality, years of potential life lost) were analysed for 2004-2023; screening performance (coverage, abnormal rate, cancer detection rate, positive predictive value, benign biopsy rate, number needed to screen, programme contribution) was assessed for 2010-2023. Trends were modelled with Joinpoint; staging followed TNM (I-II "early", III-IV "advanced").

ASIR increased from 39.3 per 100,000 women in 2004 to 54.4 in 2023 (with a transient dip to 44.9 in 2020), whereas ASMR declined from 16.6 to 10.2 per 100,000 over the same interval; the mortality-to-incidence ratio decreased from 0.42 to 0.19. YPLL_75 fell from 175.1 per 100,000 in 2004 to a nadir of 76.0 in 2018, then measured 104.9 in 2023. The proportion diagnosed at stages I-II rose from 71.1% (2010) to 88.6% (2023), with corresponding declines in stage III (22.2% → 8.7%) and stage IV (6.8% → 5.1%). Following the expansion of eligibility to ages 40-70 (from 2018), screening throughput and coverage increased, but performance remained heterogeneous across regions, with variability in recall rates, detection yield, and downstream diagnostic pathways.

Across 2004-2023, Kazakhstan experienced a favourable divergence between rising incidence and falling mortality, substantial reductions in premature mortality, and a marked shift toward earlier-stage diagnosis. These gains coincide with the maturation of the organised screening programme and broader system improvements. Consolidation will require targeted, region-specific quality-improvement bundles and resilience strategies to protect screening coverage and diagnostic capacity during system shocks.