1099 Background: The axillary lymph node ratio (LNR), i.e., the ratio of positive over excised lymph nodes offers potentially improved prognostication, selection for adjuvant therapy and inter-institutional comparability compared to conventional pathological nodal staging (pN). A consensus on appropriate cut-offs however, remains to be achieved. Values of 0.20 and 0.65 to classify patients into low, intermediate and high-risk groups were proposed by Vinh-Hung et al, in the largest study on the subject till date. We perform a validation of the LNR concept for the first time in an independent patient population from the Indian subcontinent. Methods: 225 patients with a median follow-up of 42 months (range: 2 – 246 months) who underwent upfront surgery for breast cancer at a tertiary care hospital in Delhi, India, were retrospectively analysed, using Cox multivariate regression. Results: Using the above cut-off points, 10-year disease-free survival (DFS) rates of 83%, 74% and 28% and adjusted hazard ratios (HR) of 1.19 (95% CI 0.33 to 4.37), 2.21 (95% CI 0.75 to 6.51) and 6.88 (95% CI 1.58 – 29.92; P = 0.01) were obtained for the low-, intermediate- and high-risk groups respectively. The corresponding risks for the pN1, pN2 and pN3 categories were 1.74, 1.74, and 1.35, representing inadequate, even reversed prognostic separation. When both the LNR and pN were included as continuous variables, the nodal ratio remained prognostically significant with an adjusted HR of 12.33 (95% CI 1.1 – 142.5, P = 0.04) in contrast to the number of positive nodes which were not found to be significantly associated with DFS (HR = 0.97, 95% CI 0.9 – 1.1, P = 0.41). Conclusions: The LNR outperformed the pN staging in predicting DFS in our cohort of patients, irrespective of whether it was modeled as a categorical or a continuous variable. Simultaneous analysis with pN only increased its prognostic weight and resulted in exclusion of pN from the multivariate model. Our study thus provides independent external validation of Vinh-Hung’s proposed cut-offs and contributes to the growing body of literature supporting the incorporation of a ratio-based system into breast cancer staging.
The Prognostic Significance of the Lymph Node Ratio in Axillary Lymph Node Positive Breast Cancer
