Should internal mammary lymph node sentinel biopsy be performed in breast cancer: a systematic review and meta-analysis

PURPOSE: Results from studies of internal mammary lymph node sentinel biopsy are inconsistent. METHODS: A comprehensive literature search was conducted in MEDLINE, EMBASE, Scopus, Cochrane database, and Clinical Trials. Studies reporting the rate of internal mammary lymph node sentinel biopsy (IMN-SLNB) positivity were identified. We performed pooled proportion meta-analysis using random-effects meta-analyses. The correlation of IMN and axillary lymph node (AXN) metastasis was also investigated. RESULTS: After application of inclusion and exclusion criteria, a total of 18 articles (total number of patients = 2427) were included. The pooled estimate for IMN-SLNB positivity rate was 15% (95% confidence interval (CI) 12-17%). Significant between-study heterogeneity was observed. Our results indicate that axillary lymph node metastasis is a strong predictor of IMN involvement (OR 6.01, 95% CI, 3.49, 10.34). CONCLUSION: Internal mammary lymph nodes metastasis might be underestimated. Patients with positive axillary lymph nodes have a higher risk of internal lymph nodes metastasis. As a result, IMN-SLNB might be considered in these patients. Future work needs to be done to assess whether pathological confirmed IMN metastasis can affect patients' survival.