[Analysis of the effect of ipsilateral supraclavicular lymph node metastasis on the prognosis of N3 breast cancer]

Objective: The 6th edition American Joint Committee on Cancer (AJCC) staging system for breast cancer classifies ipsilateral supraclavicular lymph node metastasis (ISLM) downing stage from M1 to N3, suggesting more patients might receive radical treatment. The aim of this study was to analyze the effect of ISLM on the prognosis of N3 breast cancer and verify the rationality of modified staging. Methods: A total of 321 breast cancer patients with N3 according to the 6th edition AJCC staging system were retrospectively analyzed. Propensity Score Matching (PSM) was used to pair the different subgroups of N3. The primary end point was disease-free survival (DFS), the secondary end point was overall survival (OS). Kaplan-Meier method was used to calculate the DFS and OS. The differences between two groups were analyzed by the Log-rank test. Results: After PSM pairing twice, 78 patients with none-ISLM and 78 patients with ISLM were enrolled in the first group; 51 patients with none-ISLM was compared patients with isolated ISLM in the second group. The results of the two groups showed that patients with none-ISLM have a prolonged DFS (the first group: 58.9 months vs 32.1 months, P=0.101; the second group: 59.0 months vs 44.0 months, P=0.533), while the OS was opposite (the first group: 87.4 months vs 140.4 months, P=0.289; the second group: 87.4 months vs 137.1 months, P=0.289). Conclusions: The prognosis of breast cancer patients with ISLM is similar to that of patients with none-ISLM in stage N3. It is reasonable to include ISLM in N3 in the 6th edition AJCC staging system. Yet, prospective studies with larger sample size are needed to further confirmation.