Risk of second malignancies in breast cancer patients who received chemotherapy: A SEER analysis.

1565Background: Chemotherapy agents used in breast cancer have carcinogenic potential and can cause malignancies. Patients with breast cancer could also be at risk for a second malignancy as well. We aimed at determining the risk of after adjuvant chemotherapy for breast cancer. Methods: We did an observational study of women who received a diagnosis of breast cancer from 1990 to 2009 using Surveillance, Epidemiology, and End Results (SEER) registries database 9 registries. Second malignancy(SM) was defined as any malignancy diagnosed 6 months after initial diagnosis of breast cancer (includes both chemotherapy-related malignancies and second primary malignancies). hormone receptor (HR) status into estrogen receptor (ER) and progesterone receptor (PR), positive (+) and negative (-). Standardized incidence ratios(SIR) were calculated based on United States population in 2000. p-value of < 0.05 is considered statistically significant. Results: Total of 245,235 cases (2,409,502 person-years) were identified,...