Isolated Contralateral Axillary Lymph Node Involvement in Breast Cancer Represents a Locally Advanced Disease Not Distant Metastases

A retrospective review was conducted to determine if isolated contralateral axillary lymph node metastasis in breast cancer patients represents a systemic spread or a locoregional spread. Our finding and the review of the literature indicate that patients with isolated contralateral axillary lymph node metastasis should be classified as N3 in the TNM system rather than M1 for appropriate staging and treatment. Background: Breast cancer metastases to an ipsilateral supraclavicular lymph node is assigned a N3 status in the TNM system and thus classified as stage III disease in the American Joint Commission on Cancer staging manual. Breast cancer metastatic to contralateral axillary lymph node (CAM) without metastases to any other distant organ is currently assigned M1 status (stage IV) instead of N3 (stage III). Patients and Methods: We retrospectively reviewed the medical records of breast cancer patients diagnosed with CAM for their clinical presentation, pathologic diagnoses, treatment, and follow-up data. Patients who had distant metastases at the time of CAM diagnosis were excluded from the study. Results: We report 12 breast cancer patients who developed CAM but no evidence of metastases in any other distant organ documented with extensive imaging workup. Imaging studies and thorough pathologic evaluation of the prophylactic total mastectomy specimen did not reveal a primary in the breast to account for the metastases in the axillary node. Conclusion: Findings of our study as well as previous studies support that lymph node metastases in the contralateral axilla represents a locoregional spread of the tumor from the index breast via lymphatics rather than hematogenous spread. Therefore, isolated CAM in breast cancer patients should not be classified as stage IV disease.