Population-based cohort study of adherence to breast screening guidelines and breast cancer mortality

A population-based cohort study in Ontario evaluated the association between adherence to the Ontario Breast Screening Program (OBSP) and death from breast cancer. Among 48.927 women aged ≥ 51 years with a breast cancer diagnosis between 2010 and 2017, 53.4% were fully adherent to screening guidelines, 13.4% were non-adherent screeners (screened at least once), and 33.3% were non-screeners. During median 3.6 years follow-up from the diagnosis 5.9% of participants died from breast cancer. Compared to adherent screeners, non-screeners and non-adherent screeners had higher rates of death from breast cancer (HR 3.59; 95% CI 3.30-3.90 and HR 1.69; 95% CI 1,47-1.95, respectively) and non-adherent screeners had lower rate of breast cancer death than non-screeners (HR 0.47; 95% CI 0.41-0.54). The authors conclude that individuals screened in the OBSP had a lower rate of death from breast cancer than non-screeners, even if they were not meeting screening guidelines.