Internal mammary sentinel node biopsy for breast cancer

Background: The purpose of this study was to determine the value of lymphoscintigraphy (LS) for internal mammary sentinel node (IMSN) identification, the metastatic rate, and the change in staging and treatment. Methods: Between 2001 and 2007 a prospective database was obtained of all patients undergoing IMSN biopsies using an open or thoracoscopic approach. Radiotracer injection was peritumoral. Results: Thirty-four patients were included. There was one man. Three had ductal carcinoma in situ. LS showed IMSN in 47.1%. The IMSN biopsy success rate was 91.2%. Seven of the 28 successfully biopsied invasive cancer patients had metastatic IMSNs (25%). Positive IMSNs were associated with positive axillary nodes in 71.4% (P = .036). All patients with positive IMSNs were upstaged and received radiation to the internal mammary chain. In 4 of 28 patients (14%) the chemotherapy plans were probably altered. In univariate and multivariate analyses tumor size, location, nuclear grade, estrogen receptors, progesterone receptors, Her-2, and histology were not significant predictors of positivity. Conclusions: IMSNs were positive in 25% of the invasive cancer patients. All had treatment changes. LS identified less than 50% of IMSNs. There are no good tumor-related predictors of IMSN positivity.