Breast-Conserving Therapy is Associated with Improved Survival Compared with Mastectomy for Early-Stage Breast Cancer: A Propensity Score Matched Comparison Using the National Cancer Database

Introduction Current recommendations for early-stage breast cancer are largely based on the NSABP B-06 trial demonstrating equivalent survival between mastectomy and lumpectomy. We sought to compare breast-conserving therapy (BCT) with mastectomy for treatment of early-stage breast cancer in a contemporary patient population. Methods A query of the NCDB PUF identified female breast cancer patients diagnosed from 2004 to 2015. Patients with stage I or II disease were included. BCT was defined as the receipt of lumpectomy plus radiation. Propensity scores were tabulated using race, age, Charlson/Deyo score, tumor site, laterality, histology, grade, size, number of nodes positive, lymph-vascular invasion, receptor status, receipt of chemotherapy, and endocrine therapy. Patients who received BCT versus mastectomy were matched using a 1:1 nearest neighbor technique. The primary outcome measured was overall survival. Results After exclusions and matching, two equal groups of 101,118 patients remained. Median follow-up was 42 months. The majority had invasive ductal histology (77%), and node-negative disease (84%). Receptor status included ER-positive (83%), PR-positive (73%), and HER2/Neu-positive (15%). Chemotherapy was received in 38% and endocrine therapy in 71%. Propensity score matching yielded equivalent groups across all target variables. The 5-year overall survival was superior for BCT compared with mastectomy (92.9% vs. 89.7%, p