Risk of New Primary Nonbreast Cancers After Breast Cancer Treatment: A Dutch Population-Based Study

Purpose To assess the risk of secondary nonbreast cancers (SNBCs) in a recently treated population-based cohort of breast cancer patients focused on the association with treatment and prognostic implications. Patients and Methods In 58,068 Dutch patients diagnosed with invasive breast cancer between 1989 and 2003, SNBC risk was quantified using standardized incidence ratios (SIRs), cumulative incidence, and Cox regression analysis, adjusted for competing risks. Results After a median follow-up of 5.4 years, 2,578 SNBCs had occurred. Compared with the Dutch female population at large, in this cohort, the SIR of SNBCs was increased (SIR, 1.22; 95% CI, 1.17 to 1.27). The absolute excess risk was 13.6 (95% CI, 9.7 to 17.6) per 10,000 person-years. SIRs were elevated for cancers of the esophagus, stomach, colon, rectum, lung, uterus, ovary, kidney, and bladder cancers, and for soft tissue sarcomas (STS), melanoma, non-Hodgkin's lymphoma, and acute myeloid leukemia (AML). The 10-year cumulative incidence of SNB...