Lymph Node Ratio as an Independent Prognostic Factor in Breast Cancer: A Retrospective Study of 4060 Patients Undergoing Axillary Lymph Node Dissection.

[BACKGROUND] Pathological nodal (pN) staging in breast cancer is based on the number of positive nodes but may be influenced by surgical extent and technique. Lymph node ratio (LNR)-the ratio of positive to total nodes-accounts for both tumor burden and nodal yield, potentially improving prognostic accuracy.

[METHODS] We retrospectively analyzed data from 4060 breast cancer patients who underwent axillary lymph node dissection (ALND) between 1995 and 2021 at a tertiary cancer center in India. Disease-free survival (DFS) and overall survival (OS) were assessed using Kaplan-Meier curves and log-rank tests. Correlation analysis and multivariate analysis were used to compare prognostic utility of LNR versus pN stage. Optimal LNR cutoffs were identified using Youden's index.

[RESULTS] The median follow-up was 93.8 months. On multivariate analysis, LNR retained a strong independent prognostic value for both DFS (HR = 2.00 for LNR 0.2-0.5; HR = 3.29 for LNR > 0.5; P < .001) and OS (HR = 1.77 for LNR 0.2 to 0.5; HR = 2.77 for LNR > 0.5; P < .001). LNR cutoffs of 0.24 (DFS) and 0.21 (OS) were identified. Stratification into 3 LNR groups (≤ 0.20, 0.21-0.50, > 0.50) showed significantly different survival outcomes (log-rank P < 0.001).

[CONCLUSIONS] LNR is a superior and independent prognostic marker compared to pN stage in breast cancer patients undergoing ALND. Incorporating LNR into prognostic models may enhance risk stratification and guide adjuvant treatment decisions.