Systematic review of synchronous contralateral axillary metastases in breast cancer: really M1 disease?

OBJECTIVE The objective of the study is to assess and quantify the effect of the appearance of synchronous contralateral axillary on breast cancer survival. Breast cancer with contralateral axillary metastases (CAM) is classified as a metastatic disease. There are few cases reported and a lack of evidence of the significance of CAM when synchronous appearance with a primary tumor and no other site of disease. METHODS A systematic review following PRISMA guidelines to evaluate the prognosis of patients with synchronous CAM without other metastatic diseases comparing with metastatic disease is conducted through a search in PubMed, Embase, Clinical Key, and Cochrane Library databases. We present one case. The median age, follow-up, clinico-pathological characteristics, status of lymph nodes, treatments, and outcomes are analyzed. RESULTS A total of 23 articles (10 case reports and 13 case series) with a total 68 patients, including our case. Median age was 48 years old. Median follow-up was 27 months. Overall survival of the series was 71.4%. Twenty-one of 49 patients reported (36.2%) were alive without disease, fourteen (28.6%) were alive with disease while the rest fourteen (28.6%) died. Inflammatory presentation and ipsilateral axilla status were related to overall survival. CONCLUSIONS Synchronous CAM in breast cancer show better outcomes in terms of overall survival than other metastatic diseases. The absence of comparative studies may not allow definitive conclusions, meanwhile, together with other authors we suggest treatment with curative intention. More studies may lead to consider a modification of TNM system.