Using nodal ratios to predict risk of regional recurrences in patients treated with breast conservation therapy with 4 or more positive lymph nodes.

Purpose. The value of nodal ratios (NRs) as a prognostic variable in breast cancer is continually being demonstrated. The purpose of this study was to use NR in patients with ≥4+ nodes to assess a correlation of NR with regional (lymph node) recurrence. Methods. Inclusion criteria was ≥8 nodes dissected with ≥4+ nodes after breast conservation therapy. Of 1060 patients treated from 1975 to 2003 who had a minimum of 8 nodes dissected, 273 were node+; 56 patients had ≥4+ involved nodes and were the focus of this study. Nodal ratios were calculated for each patient and grouped into 3 categories: high (≥70%), intermediate (40%-69%) and low (<40%). Each nodal ratio was correlated with patterns of local, regional, and distant failures and OS. Results. Outcomes for the entire cohort were BRFS-83%, NRFS-93%, DMFS-61%, and OS 63% at 10 yrs. The OS, DMFS, and NRFS correlated with N2 (4-9 nodes+) versus N3 (≥10+) status but did not correlate with BRFS, as expected. When evaluating NR, 18 pts had high NR (>70%). Only 3 patients experienced nodal recurrences, all within previously radiated supraclavicular fields. All 3 in-field regional failures occurred in the N3 group of patients with NR >70%. All were treated with a single AP field prescribed to a dose of 46 Gy at a standard depth of 3 cm. Conclusions. In this group of N2/N3 patients treated with BCT, we were able to identify patients at high risk for regional failures as those with high NR of >70% and ≥10+ nodes. While these findings need to be reproduced in larger datasets, this group of patients with NR of >70% in 4 or more positive axillary lymph nodes may benefit from meticulous targeting of regional nodes, dose escalation, and/or more intensive systemic therapies.