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.