Screening History, Stage at Diagnosis, and Mortality in Screen-Detected Breast Cancer

Screening mammography promotes early detection of breast cancer and is associated with reduced breast cancer mortality. Screening history prior to diagnosis may impact stage at diagnosis and breast cancer mortality. Among 13,028 included women, most had at least 1 prior screening (10 094 women [77.5%]) and were aged between 70 and 79 years (9034 women [69.4%]) and not dual-eligible for Medicare and Medicaid (11 475 women [88.1%]). Additionally, 3812 women (29.3%) were diagnosed with later-stage disease (T2+ or N1+) at the time of diagnosis. In multivariable analyses, prior screening was associated with 54% lower odds of later-stage breast cancer diagnosis (adjusted odds ratio, 0.46) and 36% lower hazard of breast cancer-specific death (adjusted hazard ratio, 0.63) compared with no prior screening. In the adjusted Cox proportional hazards model, having 3 or 4 prior screenings was associated with 37% reduced hazard of breast cancer-specific mortality compared with having 1 prior screening (adjusted hazard ratio, 0.63). In this cohort study of older women with screen-detected estrogen receptor-positive or human epidermal growth factor receptor 2-negative breast cancer, prior screening mammography was associated with earlier stage at breast cancer diagnosis and lower breast cancer mortality. These findings support the potential for routine screening to improve breast cancer outcomes.