The significance of intramammary lymph nodes in breast cancer: a systematic review and meta-analysis.

Intramammary lymph nodes (IntraMLNs) are frequent mostly benign incidental findings. However, they are clinically important because they can be the primary sites of metastasis and sentinel lymph nodes. Literature data regarding the clinical significance of IntraMLNs metastasis, however, remains controversial. This study aimed to perform a systematic review and meta-analysis to better define the prognostic value of positive IntraMLNs in patients with breast cancer. A systematic review of the literature without date restrictions was conducted. Five electronic medical databases were searched, and a hand-search of the reference lists of the collected articles was also performed. Studies with sufficient and relevant pathologic and clinical survival data were included. Other studies with insufficient data or normal findings were excluded. This study found 18 studies eligible for systematic review, 3 of which were eligible for outcome meta-analysis. IntraMLNs metastases were strongly correlated with axillary lymph nodes involvement. Positive IntraMLNs are reliable predictors of axillary lymph node involvement and therefore a guide for further surgical management of the axillary nodes. Even though it could be concluded that IntraMLNs metastasis is an independent predictor of outcome, this meta-analysis was limited because of the scarcity of data and the inconsistencies and heterogeneity of the outcome studies.