Contralateral uptake and metastases in sentinel lymph node mapping for recurrent breast cancer

Background and Objectives: Sentinel lymph node mapping as a constitutive component in the staging process for invasive breast cancer continues to gain acceptance. We have identified two patients with recurrent invasive breast cancer in whom contralateral sentinel lymph node uptake and metastases, respectively, were detected. Such findings have not been previously reported in our review of the medical literature between 1966 and October 2004. Methods: Sentinel lymph node mapping was performed on two patients with recurrent invasive breast cancer at our institution. At the time of their index diagnosis, both had received breast conserving surgery and an axillary lymph node dissection with post-operative radiotherapy (RT). All lymph nodes and margins of resection were without tumor. Both patients remained with no evidence of disease for years until routine serial screening mammography was interpreted as suspicious. Each underwent a stereotactic biopsy of the ipsilateral breast corresponding to the mammographic abnormality. Pathology confirmed invasive ductal carcinoma. Both patients refused the recommended salvage mastectomy. Principal Results: During a second attempt at breast conservation, sentinel lymph node mapping-which is typically contraindicated for patients with prior axillary surgery-revealed contralateral axillary uptake for both patients. The respective contralateral sentinel node was excised with pathology revealing no tumor in one case, and a microscopic focus of metastatic carcinoma in the second case. Major Conclusion: Some patients may benefit from sentinel lymph node mapping prior to salvage mastectomy. Identifying uptake in a contralateral sentinel lymph node may change the multi-disciplinary management of recurrent invasive breast cancer to include a contralateral axillary dissection, chemotherapy, and/or RT to the contralateral axilla.