Breast conserving therapy and mastectomy revisited: Breast cancer-specific survival and the influence of prognostic factors in 129,692 patients

This large population-based study compared breast-conserving surgery with radiation therapy (BCT) with mastectomy on (long-term) breast cancer-specific (BCSS) and overall survival (OS), and investigated the influence of several prognostic factors. Patients with primary T1-2N0-2M0 breast cancer, diagnosed between 1999 and 2012, were selected from the Netherlands Cancer Registry. We investigated the 1999–2005 (long-term outcome) and the 2006–2012 cohort (contemporary adjuvant systemic therapy). Cause of death was derived from the Statistics Netherlands (CBS). Multivariable analyses, per time cohort, were performed in T1-2N0-2, and separately in T1-2N0-1 and T1-2N2 stages. The T1-2N0-1 stages were further stratified for age, hormonal receptor and HER2 status, adjuvant systemic therapy and comorbidity. In total, 129,692 patients were included. In the 1999–2005 cohort, better BCSS and OS for BCT than mastectomy was seen in all subgroups, except in patients 50 years, not treated with chemotherapy and with comorbidity. Both treatments led to similar BCSS in patients