The prognostic significance of nodal ratio on breast cancer recurrence and its potential for incorporation in a new prognostic index

Axillary nodal status is an inherent part of prognostic tools such as the Nottingham Prognostic Index (NPI). Literature suggests that nodal ratio is a stronger predictive parameter than the total number of positive nodes sampled. Studies also note improved survival in node-negative patients with a larger proportion of nodes excised. The aim of this study was to assess disease-free survival (DFS) comparing the number of negative and positive nodes excised and nodal ratio as the predictive parameters. Consecutive axillary lymph node dissections (ALND) were analyzed over a 25-year period. Data were analyzed using Cox Regression and Kaplan-Meier survival curves. Eight hundred and forty-nine ALNDs were identified, with 327 positive ALNDs and 268 node negative ALNDs incorporated in the study following exclusions. A prognostic index based on nodal ratio was devised and applied retrospectively to 327 positive ALNDs prior to 2002. This index was then prospectively validated in 116 consecutive positive ALNDs from 2002 to 2005. In node negative ALNDs, no significant difference in DFS was noted in patients having </≥10 nodes, or having </≥14 nodes removed. In node-positive patients, nodal ratio was a stronger predictor of DFS than total positive nodes excised. A prognostic index incorporating nodal ratio more accurately predicts survival than the NPI in node-positive patients as assessed in both a retrospective and a prospective patient cohort. Prognostic indices incorporating nodal ratio may prove more accurate than the current NPI. The extent of ALND did not impact survival in node-negative patients.