Breast Cancer Patients with Extra-Axillary Sentinel Nodes Only may be Spared Axillary Lymph Node Dissection

Background  In breast cancer patients with only extra-axillary sentinel nodes, surgeons typically perform axillary node dissection. The purpose of this study was to evaluate our approach to spare such patients further dissection based on the hypothesis that a sentinel node is not necessarily located in the axilla. Methods  Between March 11, 1999 and March 5, 2008, 1,949 breast cancer patients underwent lymphatic mapping with preoperative lymphoscintigraphy and intraoperative use of a gamma-ray detection probe and patent blue dye. The tracers were injected into the tumors. Results  Eighty-two of the 1,949 patients had only extra-axillary drainage on their lymphoscintigrams. A sentinel node was harvested from the axilla in 62 patients but not in the remaining 20 patients. No axillary lymph nodes were removed in 4 of these 20 patients, suspicious palpable nodes were excised in another 4 patients, and node sampling was done in the remaining 12. These nodes were all free of disease. All sentinel nodes outside the axilla were removed. Two patients had a metastasis in an internal mammary chain node. No lymph node recurrences were detected in or outside the axilla in any of the 20 patients with a median follow-up time of 49 months. Conclusion  4% of the patients have only extra-axillary drainage on preoperative lymphoscintigrams. It is worthwhile to explore the axilla since a sentinel node can be found in three-quarters. In the remaining 1% without axillary sentinel nodes, axillary sampling seems unnecessary and the approach to refrain from axillary dissection appears valid.