The effect of the number of negative lymph nodes removed during surgery on the survival and recurrence rates of patients with breast cancer after surgery.

OBJECTIVE

Although numerous studies have assessed the prognostic value of negative lymph nodes (NLN) counts in breast cancer (BC), their findings on survival outcomes have been inconsistent. This study aimed to determine the impact of the number of NLNs removed on overall survival (OS) and recurrence-free survival (RFS) in patients with BC undergoing surgical treatment.

METHODS

In this multicenter cohort study, we reviewed medical records of 1,384 patients with histologically confirmed BC who underwent a mastectomy from 2011 to 2022, retrospectively. Patients were stratified into three groups according to the number of NLNs removed: (1) < 10, (2) 10-20, and (3) > 20. The primary endpoints were 5-year OS and RFS. Survival was assessed by Kaplan-Meier analysis using log-rank tests to compare survival curves, and Cox proportional hazards models were used to identify prognostic factors.

RESULTS

At a mean follow-up of 54.6 months, the 5-year OS and RFS were estimated to be 65.5% and 54.2% respectively. Kaplan-Meier curves showed significantly improved survival in patients with ≥ 10 NLNs removed. Multivariate Cox regression demonstrated that the OS rate in patients with the number of NLNs removed > 20 was significantly better than in patients with the number of NLNs removed < 10 (HR: 0.69, 95% CI: 0.56, 0.86, P: 0.001). Also, the OS rate in patients with the number of NLNs removed between 10 and 20 was significantly better than in patients with the number of NLNs removed < 10 (HR: 0.85, 95% CI: 0.75, 0.96, P: 0.001). Additionally, age < 45, higher BMI, comorbidities, advanced tumor/nodal stage, high histologic grade, HER2 status, higher Ki-67, and higher lymph node ratio were independently associated with poorer OS and RFS.

CONCLUSION

The removal of a greater number of tumor-free lymph nodes was independently associated with improved 5-year OS and RFS in BC patients following surgery.