Lymph Node Ratio in Sentinel Lymph Node Biopsy Era: Are We Losing Prognostic Information?

Lymph node ratio (LNR) is considered to have prognostic significance in patients with solid tumors. To better understand its application, we reviewed 553 patients with node-positive early-stage breast cancer (EBC), concentrating on clinical, pathologic, treatment, and outcome data. Background The number of involved axillary lymph nodes (LNs) found pathologically is regarded as a significant prognostic factor in early-stage breast cancer (EBC). Recently, there is speculation that LN ratio (LNR) may be a better surrogate at predicting cancer-specific outcome than number of involved LNs. This study investigated prognostic value of LNR, using predetermined cutoff values. Methods Data included all women diagnosed with node-positive EBC between January 1, 2001, and December 31, 2010 (N = 553). Retrospective evaluation for clinical, demographic, and pathologic data was performed. Most had axillary node clearance (ANC) (548/553; 99.1%). Cohorts were divided by LNR risk groups (low: ≤ 0.20; intermediate: 0.21-0.65; high: >0.65). Proportional hazard modeling was undertaken to evaluate whether LNR was associated with overall survival (OS). Results Median follow-up was 59.8 months. LNR distribution was as follows: low, 303/553 (54.8%); intermediate, 160/553 (28.9%); high, 90/553 (16.3%). Kaplan-Meier estimates for OS were stratified by LNR: low-risk group had better outcome for OS (P < .001). Overall 5- and 10-year OS was 63% and 58%, respectively. Number of positive LNs correlated with 10-year OS (66%, 48%, and 48% for patients with N1, N2, and N3 stage, respectively; P < .001). LNR also correlated with 5-year OS (69%, 48%, and 41% for low-, intermediate-, and high-risk groups, respectively; P < .001). Significantly, LNR on multivariate analysis also formed a prognostic model when combined with age, estrogen receptor status, PgR status and, HER2 status (P < .001). Conclusion The Findings support LNR as a predictor for OS in EBC. LNR should be considered an independent prognostic variable to current prognostic instruments already in use.