Is radiation alone adequate treatment to the axilla for patients with limited axillary surgery? implications for treatment after a positive sentinel node biopsy

Purpose: To estimate the possible efficacy of axillary radiation therapy (AXRT) following a positive sentinel node biopsy (SNB), we evaluated the risk of regional nodal failure (RNF) for patients with clinical Stage I or II, clinically node-negative invasive breast cancer treated with either no dissection or a limited dissection (LD) defined as removal of 5 nodes or less followed by AXRT. Materials and Methods: From 1978 to 1987, 292 patients underwent AXRT in the absence of axillary dissection; 126 underwent AXRT following LD. The median dose to the axilla was 46 Gy. The median dose to the supraclavicular fossa was 45 Gy. Among patients found to have positive nodes on LD, adjuvant chemotherapy and tamoxifen were administered to 81% and 7% of subjects, respectively. All patients had potential 8-year follow-up. Results: Six of the 418 patients (1.4%) developed RNF as a first site of failure within 8 years. Among these 6 patients (1.4%) with RNF as the first site of failure, 4 had simultaneous distant and regional recurrences; and 2 had isolated axillary failures. Three of the 292 patients (1%) with no axillary dissection, none of 84 patients with pathologically negative nodes and 3 of 42 patients (7%) with pathologically involved nodes had RNF as a first site of failure. Radiation pneumonitis developed in 5 patients (1.2%), brachial plexopathy in 5 (1.2%) and arm edema in 4 (1.2%). In all cases, radiation pneumonitis and brachial plexopathy were transient. Conclusion: These results imply that AXRT may be an effective and safe alternative to completion dissection for treatment of the axilla following a positive SNB. Further studies comparing these two options in specific patient subgroups are needed.