Background: Accurate breast cancer staging is essential for optimal management of adjuvant therapies. While breast lymphatic drainage involves both axillary and internal mammary (IM) lymph node (LN) basins, IM LN sampling is not routinely advocated. The current study analyzes the incidence of IM LN metastases sampled during free flap breast reconstruction and subsequent changes in adjuvant treatment. Methods: A retrospective analysis of patients with positive IM LN biopsies during free flap breast reconstruction was performed. Pre-reconstruction surgical and adjuvant therapies as well as staging and prognostic data were recorded. Change in adjuvant therapies based solely on IM LN positivity was determined. Results: IM LN metastases were found on 28 (1.3%) out of 2057 patients and comprised the study population. Mean age was 49 years with pre-reconstruction chemotherapy or radiation administered in 50 or 54% of cases, respectively. Five (18%) patients had previously undergone lumpectomy with axillary sampling. Mean tumor size was 3.1 cm with tumor location evenly distributed among all four quadrants. Ten (36%) patients had isolated IM LN metastases Patients with both axillary and IM disease had larger lesions, increased prevalence of pre-reconstruction chemotherapy and radiation. Based exclusively on positive IM LN disease, 17 (63%) patients had a change in adjuvant therapy. Conclusion: Despite the low incidence of IM LN metastases, IM LN biopsy during free flap breast reconstruction is recommended. In 36% of cases, nodal metastases were isolated to the IM nodes. Identification of IM metastases influenced adjuvant therapies in a majority of cases.
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