The lymph node ratio as an independent prognostic factor for non-metastatic node-positive breast cancer recurrence and mortality.

PURPOSE

To examine the prognostic value of lymph node ratio (LNR) in pathological nodal (pN) stage breast cancer patients. Also, to analyse additional clinical and pathologic prognostic factors and the impact of LNR among molecular subtypes.

METHODS

Among a total of 3088 patients, 1004 women with non-metastatic lymph node-positive breast cancer were analysed. The patients were classified into low (≤0.20), intermediate (0.20 to 0.65) and high-risk (>0.65) LNR groups. Univariate and multivariate Cox proportional hazards regression model for disease-free survival (DFS), and overall survival (OS) were performed to evaluate the prognostic value of LNR.

RESULTS

The median LNR was 0.17 (range 0.02-1.00). Of the patients, 55.7% were in low, 32.1% in intermediate, and 12.3% in high risk group. When compared with low risk group, high risk group had more often large tumor size and high grade tumor with lymphovascular invasion. The median follow-up period was 46.8 months. The 5-year breast cancer-specific OS and DFS rates for patients with low, intermediate, and high were 88%-67%, 65%-48% and 53%-24%, respectively (both plog-rank<0.0001). On multivariate analysis, pN stage and LNR were both independent predictors of survival, however, an overlapping between N1 (250 months, 95% confidence interval [CI] 88.15-413.21) and N2 (176 months, 95% CI 129.51-222.93) curves in pN staging was determined. We also observed clear prognostic separation for triple negative breast cancer with LNR survival over pN staging.

CONCLUSION

The LNR predicts survival more accurately than pN staging in node-positive breast cancer patients. The use of LNR may standardize the staging and guide decisions for adjuvant treatments.