Impact of internal mammary lymph node biopsy during microsurgical breast reconstruction on multidisciplinary breast cancer management decisions.

Abstract

Internal mammary lymph nodes (IMLNs) are the second most common site of nodal metastasis in breast cancer, however, they are infrequently sampled in contemporary practice. We report a series of positive IMLNs identified during autologous breast reconstruction and contextualize these findings within the current literature. A retrospective case series was conducted of patients with positive IMLN(s) during autologous breast reconstruction between 2015 and 2024. Primary outcome measures included stage migration and modifications to therapy. A concurrent PubMed and MEDLINE literature review was performed. Six patients were included in the study (mean age 50±8.92 years). All patients had invasive carcinoma, including 5 invasive ductal and 1 invasive lobular carcinoma. Two patients had isolated IMLN metastases, and 4 had concomitant axillary nodal involvement. Preoperative imaging visualized a suspicious IMLN in 1 patient (16.7%). Pathologic stage migration occurred in 1 patient (16.7%); however, IMLN assessment influenced oncologic management in all 6 cases. There were no biopsy-related complications. Across 20 published studies and 4887 patients, 152 had positive IMLNs. Twelve studies used selective sampling, and 8 studies employed routine sampling. There was a mean positive IMLN detection of 5.7% per study. Three studies re--ed sampling only suspicious nodes, whereas 17 (85.0%) advocated for routine sampling of all IMLNs encountered during vessel dissection. Opportunistic IMLN biopsy during autologous breast reconstruction often alters staging and treatment. Given the safety and feasibility of this practice, routine sampling during internal mammary vessel preparation should be considered to better inform multidisciplinary breast cancer management decisions.