Effect of a national population-based breast cancer screening policy on participation in mammography and stage at breast cancer diagnosis in Taiwan

In Taiwan, a Cancer Screening Quality Improvement Program (CAQIP), implemented in 2010, provides financial support to qualified hospitals to improve accessibility. This study examined whether the CAQIP program increased participation in mammography and achieved more early stage diagnosis of breast cancer. We utilised a natural experiment to compare outcomes of interest in women aged 50–69 years with their first mammography date in two different phases, 2005–2009 and 2010–2014. Propensity score matching was used to match comparable cohorts in each phase. In total, 468,259 matched participants in phases 1 and 2 were analyzed. Patient-level logistic regressions were used and adjusted for patient risk factors. Compared with phase 1, our findings indicated women in phase 2 were more likely to have repeat mammography participation (OR, 1.33; 95 % CI, 1.32–1.34), and be diagnosed with early stage breast cancer (OR, 1.15 times; 95 % CI, 1.05–1.26). Women living in rural areas were less likely to repeatedly participate mammography (OR, 0.86; 95 % CI, 0.85–0.86) and experience early diagnosis (OR, 0.90, 95 % CI, 0.81–0.99). Women at low socioeconomic status were less likely to experience early diagnosis, and those with reproductive and hormonal risk factors were less likely to repeatedly participate mammography. Our findings provide evidence of potential benefits of health policy intervention to improve accessibility on participation in mammography and early stage diagnosis of breast cancer.