Lymph Node Ratio (LNR): Predicting Prognosis after Neoadjuvant Chemotherapy (NAC) in Breast Cancer Patients

Axillary lymph node status is an important prognostic factor in breast cancer (BC). Residual nodal disease burden after neoadjuvant chemotherapy (NAC) is one of the important prognostic factors to determine the prognosis and in the treatment of BC. Lymph node ratio (LNR) defined as the ratio of the number of positive lymph nodes to total excised axillary lymph nodes, may be a stronger determinant of prognosis than pN in axillary nodal staging, although there is very limited data evaluating its prognostic value in the setting of NAC. In this cohort of patients, we studied the utility of LNR in predicting recurrence and overall survival (OS) after NAC.

An Institutional cancer registry was queried from 2009 to 2014 for women with axillary node-positive BC with no evidence of distant metastasis, and who received NAC followed by surgery for loco-regional treatment (axillary dissection with breast conserving surgery or total mastectomy). Patients with axillary complete response were excluded. Locoregional recurrence (LRR), distant recurrence (DR) and overall survival (OS) rates were reviewed regarding pN and LNR.

A total of 179 patients were analyzed. Median follow up time was 24 [25%, 75%: 13-42] months. Patients with pN1 in comparison to pN2 and pN3 had lower rate of LRR (9% vs. 15% and 14%, respectively; p=0.41), lower rate of DR (14% vs. 25% and 27%, respectively, p=0.16) and increased rate of OS (89% vs. 79% and 78%, respectively, p=0.04). In comparison to patients with LNR >20%, patients with LNR ≤20% had lower LRR (9% vs. 14%, p=0.25), lower DR (13% vs. 27%, p=0.01) and improved OS (89% vs. 79%, p=0.02) rates. In the pN1 group, patients who had a LNR >20% had higher DR (22% vs. 14%, p=0.48) rates in comparison to patients with LNR ≤20%. In ER/PR (+) patients who had LNR ≤20% DR was 6% compared with 23% in patient who had LNR >20% (p=0.02), and in triple negative patients' OS rate was significantly better compared the LNR less/equal or more than 20% (71% vs 33%, p=0.001).

Our study demonstrated that LNR adds valuable information for the prognosis after NAC and this additional information should be considered when deciding further treatment and follow-up for patients who had residual tumor burden on the axilla. This observation should be tested in a larger study.