Trends in Regional Nodal Management of Breast Cancer Patients with Low Nodal Burden

Background: American College of Surgeons Oncology Group Z0011 confirms the safety of omitting axillary lymph node dissection (ALND) and regional nodal irradiation (RNI) in breast cancer patients with one to two positive sentinel lymph nodes (SLNs), without compromising disease-free survival (DFS) and overall survival (OS). In contrast, the NCIC MA20 trial showed improved DFS in node-positive patients undergoing ALND and RNI. We sought to examine how these data have influenced the management of patients with limited nodal burden. Methods: Using the National Cancer Database, patients diagnosed between 2010 and 2015 and who met the criteria for Z0011 were identified. Logistic regression was used to analyze factors associated with practice patterns. The Cox proportional hazards model was used to assess the association of ALND and RNI with OS. Results: Omission of ALND in Z0011-eligible patients reached 89.2% in 2015. This Z0011-compliant group was more likely to undergo RNI compared with the non-compliant group (36.4% vs. 31.3%; p < 0.05), with RNI increasing to 43.8% by 2015. Factors associated with the use of RNI included later year of diagnosis [odds ratio (OR) 1.8, 95% confidence interval (CI) 1.6–2.1], hormone receptor-negative tumor (OR 1.2, 95% CI 1.1–1.4), grade 3 tumor (OR 1.2, 95% CI 1.1–1.3), treatment at a non-academic site (OR 1.2, 95% CI 1.1–1.3) and two versus one positive SLN (OR 2.0, 95% CI 1.8–2.2). With 43 months median follow-up, RNI was not associated with improved OS. Conclusion: Since the publication of Z0011, the omission of ALND has become widespread; however nearly half of these women now receive RNI. The optimal radiation therapy approach for this low nodal burden population warrants further study.