Internal mammary sentinel lymph node biopsy for breast cancer: a long-term follow-up research for assessment of prognosis and guiding individualized internal mammary lymph node irradiation
Background and purpose: Internal mammary lymph node irradiation (IMNI) improves survival in patients with internal mammary lymph node (IMLN) high-risk metastatic breast cancer. The purpose of this study was to study the advantages of internal mammary sentinel lymph node (IMLN) biopsy (IM-SLNB) for assessing prognosis and directing individualized IMNI. Methods: This study evaluated patients recruited in three prospective clinical trials (NCT01642511, NCT03541278, and NCT03024463) from November 2011 to December 2021, assessed for prognostic risk variables based on IMSLN metastatic status and prognosis between subgroups. In patients who received regional lymph node irradiation, the implementation status, survival benefit, and influence of IMNI on radiation-induced lung injury (RILI) were studied. The primary endpoint was disease-free survival (DFS), with overall survival (OS) and RILI as secondary endpoints. Results: The study enrolled 537 patients and had a 60-month median follow-up. Patients with IMSLN metastasis had a significantly worse 5-year DFS and OS (DFS: 95.1% vs 71.4%, OS: 99.1% vs 90.1%, both P<0.05), and IMSLN metastatic status was an independent risk factor for DFS and OS (both P<0.05). Adding IMNI did not improve DFS (P = 0.099) or OS (P = 0.486) in patients with negative IMSLN, while it did increase the risk of RILI (OR = 3.678, P<0.05). However, adding IMNI improved 5-year DFS (87.3% vs 52.5%, P = 0.040) for patients with positive IMSLN but had no effect on OS (P = 0.603). Conclusion: This study discovered that IMSLN metastatic status has significant prognostic importance. Patients with IMSLN metastasis who receive IMNI have significantly improved prognosis, and patients without IMSLN metastasis have a much lower risk of RILI by being exempt from IMNI without worse prognosis
