Abstract
OBJECTIVES: This study investigated the effect of mammography screening on the long-term survival of breast cancer (BC) patients aged 40 years or older according to their screening history and duration since screening. METHODS: The study cohort was organized from 3 nationwide databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. We included 24,387 women diagnosed with invasive BC or ductal carcinoma in situ in 2008 and 2009 and followed up until December 31, 2019. Cox proportional-hazards regression was used to investigate the effect of BC screening on the risk of death. RESULTS: Overall, 20,916 of 24,387 patients (85.8%) were alive at the end of the follow-up period (median: 10.5 years). The long-term survival rate was significantly lower in the never-screened group (80.3%) than in the screened group (88.9%) (p<0.001). A 35% reduction in the risk of BC death (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.60 to 0.70) from screening was observed. A subgroup analysis according to the cancer stage showed 62%, 36%, and 24% lower risks of BC death for the localized stage, regional stage, and distant stage, respectively. Women aged 40-49 years received the least benefit from BC screening (HR, 0.71; 95% CI, 0.62 to 0.81). CONCLUSIONS: Mammography screening was effective in reducing the risk of BC-specific death in Asian women across all cancer stages. However, this effect was relatively small among women in their 40s, suggesting that more detailed and specialized screening strategies are needed for that age group.