Number of negative lymph nodes should be considered for incorporation into staging for breast cancer.

This study aimed to investigate the prognostic value of the number of involved lymph nodes (pN), number of removed lymph nodes (RLNs), lymph node ratio (LNR), number of negative lymph nodes (NLNs), and log odds of positive lymph nodes (LODDS) in breast cancer patients. The records of 2,515 breast cancer patients who received a mastectomy or breast-conserving surgery were retrospectively reviewed. The log-rank test was used to compare survival curves, and Cox regression analysis was performed to identify prognostic factors. The median follow-up time was 64.2 months, and the 8-year disease-free survival (DFS) and overall survival (OS) were 74.6% and 82.3%, respectively. Univariate analysis showed that pN stage, LNR, number of RLNs, and number of NLNs were significant prognostic factors for DFS and OS (all, P < 0.05). LODDS was a significant prognostic factor for OS (P = 0.021). Multivariate analysis indicated that pN stage and the number of NLNs were independent prognostic factors for DFS and OS. A higher number of NLNs was associated with higher DFS and OS, and a higher number of involved lymph nodes were associated with poorer DFS and OS. Patients with a NLNs count > 9 had better survival (P < 0.001). Subgroup analysis showed that the NLNs count had a prognostic value in patients with different pT stages and different lymph node status (log-rank P < 0.05). For breast cancer, pN stage and NLNs count have a better prognostic value compared to the RLNs count, LNR, and LODDS. Number of negative lymph nodes should be considered for incorporation into staging for breast cancer.