Contralateral axillary nodal involvement from invasive breast cancer

Metastatic breast cancer to the contralateral axilla (CAM) is defined as stage IV disease. We postulate that CAM represents an extension of local-regional disease rather than distant metastasis and may have a better outcome. A single-institution, retrospective review of breast cancer cases from January 2005 and May 2011 was performed to identify cases with CAM. Eligibility for the study included unilateral primary breast cancer at presentation with synchronous/metachronous documented CAM without a documented primary invasive breast cancer within the contralateral breast by surgery or MRI. Clinicopathologic data was recorded for these patients (pts). Thirteen pts were identified. 12/13 (92%) pts presented with a locally advanced breast tumor or an ipsilateral in-breast recurrence. 10/13 (77%) pts had documented dermal involvement of tumor either at initial presentation or local recurrence. CAM occurred synchronously with the initial primary tumor (5 pts, 38%), concomitant with a local recurrence (5 pts, 38%), metachronously with the initial tumor (1 pt, 8%), and metachronously with a local recurrence (2 pts, 15%). Three patients had other distant disease at presentation. Of the other 10 pts, seven developed distant disease with a mean follow up of 3.6 years (range 0.3-7.6 years). Three pts have no evidence of disease at a mean follow up of 5.8 years (range 1.5-8.2). CAM may have different prognostic implications than other distant metastases and may occur through dermal lymphatic spread. Further study is warranted on the prognosis and management of these challenging and rare cases.