Single-center retrospective study of effect of breast cancer screening interval on rate of late-stage disease at diagnosis and overall survival

Controversy continues regarding the effect of screening mammography on breast cancer outcomes. A retrospective study at the University of Pittsburgh (PA) Medical Center examined the effect of screening interval on rate of late-stage disease and overall survival. The study included 8,145 patients with breast cancer between 2004 and 2019 and information on prediagnosis screening history. Screening was considered annual if time interval between the two screening mammograms immediately preceding diagnosis was ≤ 15 months, biennial if >15 and ≤ 27 months, and intermittent if > 27 months. The percentage of late-stage cancers at diagnosis (TNM stage IIB or worse) increased from 9% with annual screening to 14% with biennial screening and 19% with intermittent screening (p<0.001). This trend persisted regardless of age, race, and menopausal status. Biennial screening (HR 1.42; 95% CI 1.11-1.82) and intermittent screening (2.69; 2.11-3.43) were associated with substantially worse overall survival. The authors conclude that annual mammographic screening was associated with lower risk of late-stage cancer and better overall survival across clinical and demographic subgroups.