Prognostic value of axillary lymph node status after neoadjuvant chemotherapy. Results from a multicentre study

Background The prognostic value of lymph node involvement after neoadjuvant chemotherapy for breast cancer is not straightforward. We evaluated whether lymph node involvement is associated with overall survival in patients treated with neoadjuvant chemotherapy and whether Lymph Node Ratio (LNR – ratio of the positive to excised axillary lymph nodes) is a superior prognosticator when compared to ypN status (according to the pTNM classification). Methods Three hundred and fourteen patients receiving neoadjuvant chemotherapy in Geneva, Singapore or Kuala Lumpur were pooled for analysis. We evaluate the prognostic value of the LNR [zero, low (>0 and 0.65)] and ypN staging [ypN0, ypN1, ypN2 and ypN3] with multivariate Cox regression analysis. Results When using the LNR classification, 88 patients were categorised as zero, 91 as low, 82 as intermediate and 53 as high risk. For classic ypN staging, 88 were ypN0, 126 ypN1, 58 ypN2 and 42 ypN3. Compared to the low risk category, LNR zero corresponded to an adjusted hazard ratio [HRadj] of 0.4 (95%CI, 0.2–0.9), intermediate risk LNR to a HRadj of 1.2 (0.7–2.2) and high risk LNR to a HRadj of 2.7 (1.5–5.0). Similarly, the ypN0 category corresponded to a HRadj of 0.3 (0.2–0.7), ypN2 to a HRadj 1.1 (0.6–2.0) and ypN3 to a HRadj 2.2 (1.3–3.8) compared to ypN1 patients. Conclusion Lymph node status after neoadjuvant chemotherapy predicts overall survival. In patients treated with neoadjuvant chemotherapy, LNR does not seem to be superior to classic ypN staging.