Second Cancer, Breast Cancer, and Cardiac Mortality in Stage T1aN0 Breast Cancer Patients With or Without External Beam Radiation Therapy: A National Registry Study

Abstract

Introduction/BackgroundWith improved BC screening and treatment, the risk for long-term toxicities of treatments must be considered, especially in good prognosis patients. In this study we examined the outcome, risks of second cancers, and cardiac mortality with RT for early-stage BC from recent years. Materials and MethodsAnalysis of the SEER database was conducted for women who had stage T1aN0 BC as their first primary malignancy between 1990 and 1997 and were treated with partial or complete mastectomy with or without external beam RT. The overall survival (OS), BC-specific survival (BCSS), cardiac cause-specific survival (CCS), and deaths from second cancers in the chest area were compared between the RT and no-RT groups. ResultsOf the 6515 women identified, 2796 received RT and 3719 did not. The median age group (60-64 years) and follow-up lengths (approximately 15 years) were similar. Compared with the RT group, the no-RT group was associated with lower 10-year OS (85.5% vs. 79.3%; P < .0001), BCSS (97.3% vs. 96.4%; P = .04), and CCS (97.0% vs. 93.8%; P < .0001). In the RT group, left-sided BC was not associated with higher cardiac mortality. There were no statistically significant incidences in mortality due to subsequent cancers. The most common second cancer mortality included 114 (2%) lung, 25 (0.4%) lymphoma, 19 (0.3%) leukemia, 3 (0.05%) soft tissue, and 2 (0.03%) esophagus. ConclusionThis review of SEER data suggests that secondary malignancy in the chest area and cardiac mortality are rare after RT in the 1990s for T1aN0 BC.