Lymph Node Ratio Analysis After Neoadjuvant Chemotherapy is Prognostic in Hormone Receptor-Positive and Triple-Negative Breast Cancer

Abstract

Background: Lymph node ratios (LNR), the proportion of positive lymph nodes over the number excised, both defined as ranges and single ratio values are prognostic of outcome. Little is known of the prognostic value of LNR after neoadjuvant chemotherapy (NAC) according to molecular subtype.

Methods: From 2003 to 2014, patients who underwent definitive surgery after NAC were identified. LNR was calculated for node-positive patients who received axillary dissection or had at least 6 nodes removed. DFS was calculated using the Kaplan-Meier log rank test for yp N0-3 status, LNR categories (LNRC) ≤0.20 (low), 0.21-0.65 (intermediate), >0.65 (high), and single LNR values.

Results: Of 428 NAC recipients, 263 were node negative and 165 (38.6 %) node positive: ypN1 = 97 (58.8 %), ypN2 = 43 (26.1 %), and ypN3 = 25 (15.2 %). Among node-positive cancers, the median number of LN removed was 14 (range, 6-51) and the median LNR was 0.22 (range, 0.03-1.0). Nodal stage was inversely associated with 5-year DFS: 91.5 % (ypN0), 74.5 % (ypN1), 49.8 % (ypN2), and 50.7 % (ypN3) (p < 0.001). LNRC was similarly inversely associated with DFS: 69.1 % (low), 71.4 % (intermediate), 49.3 % (high) (p < 0.001). Significant associations between LNRC and DFS were demonstrated in hormone receptor (HR)-positive and triple negative breast cancer (TNBC) subtypes, p = 0.02 and p = 0.003. A single-value LNR ≤ 0.15 in node-positive, HR-positive (94.1 vs 67.7 %; p = 0.04) and TNBC (94.1 vs 47.8 %; p = 0.001) groups was also significant.

Conclusions: Residual nodal disease after NAC, analyzed by LNRC or LNR = 0.15 cutoff value, is prognostic and can discriminate between favorable and unfavorable outcomes for HR-positive and TNBC cancers.