Breast cancer recurrence and mortality among survivors of childhood cancer

Childhood cancer survivors are at high risk for developing breast cancer as a treatment-related neoplasm. Their risk for, and survival after, breast cancer recurrence has not been characterized. In this study, female survivors had a 10-year breast cancer recurrence risk of 14% (95% confidence interval [CI] = 10% to 20%) similar to patient controls with sporadic breast cancer matched by age, race, ethnicity, and disease characteristics (n = 201 pairs; P = .62). Among survivors with recurrent breast cancer (n = 68), first breast cancers were largely early stage (0-II: 77%). Nearly half (47%) underwent bilateral mastectomies, with 81% performed before recurrence, predominantly from distant metastases. Survivors' 10-year mortality risk after breast cancer recurrence was 89% (95% CI = 61% to 97%), statistically significantly exceeding patient controls (40%; 95% CI = 16% to 57%; P = .0013), for an adjusted 2.8-fold greater risk. Breast cancer was the leading cause of death in these survivors; the 10-year cause-specific mortality probability was 67% (95% CI = 53% to 83%). Comprehensive investigations of breast cancer recurrence drivers and adverse outcomes in this population are needed.