Implication of Intramammary Lymph Node Metastasis in the Breast: A Review of the Literature

Background: The impact of positive intramammary lymph node (IM LN) on the prognosis of patients with breast cancer has been debated for years; likewise, the standard management of patients with positive IM LN remains unclear, especially when it is identified by preoperative imaging or by sentinel lymph node biopsy. The present study aims at reviewing the level of concurrent involvement of IM LN and axillary nodes to clarify the management of patients with breast cancer with positive IM LN and clinically negative axilla or negative axillary sentinel lymph nodes. Methods: We reviewed all published studies on IM LN metastasis in breast cancer from 1980 to 2016 in 4 major databases. Twenty-five studies containing data on pathologic examination of IM LN were included, in twenty- two of which, pathologic status of IM LN and axillary lymph nodes were exactly available. Results: The incidence of positive IM LN is highly variable (0%-100%). Positive IM LNs were associated with positive axillary lymph nodes in more than half of patients, but isolated involvement of IM LN were documented in significant number of patients in various studies. Conclusions: Although metastatic IM LN could often be associated with axillary nodal involvement, it could be the only site of breast cancer spread; hence, the concept stating that positive IM LN mandate further axillary dissection needs to be debated.