Peripheral Neutrophil to Lymphocyte Ratio (NLR), a cogent clinical adjunct for Ki-67 in breast cancer.

Background: Clinical utility of Ki-67 immunohistochemistry (IHC) in breast cancer (BC) is mainly limited to decide for the use of chemotherapy and estimate prognosis in patients with either Ki-67 index < 5% or > 30%; however, lacunae still exists pertaining to its analytical validity. Neutrophilia is common in cancer with accompanying lymphocytopenia. Neutrophil to lymphocyte ratio (NLR) captures the intricate balance between pro-tumor neutrophilia and anti-tumor lymphocyte immunity. This study aimed to correlate cellular proliferation in breast cancer with NLR.

Methods: An observational study was carried out including 73 cases of BC; pre-treatment NLR and Ki-67 grading were performed. NLR < 3 was considered low, while ≥ 3 was high. The Ki-67 expression was graded as low ≤ 5%, intermediate 6-29%, or high ≥ 30%. Various clinico-pathological variables were studied, and the association of categorical variables was analyzed using Pearson's chi-square test, and a p-value of < 0.05 was taken as significant.

Results: Ki-67 correlated significantly with modified Scarff-Bloom-Richardson (SBR) grade (p < 0.01), and tumor-node-metastasis (TNM) stage (p < 0.001). Correlation of NLR was not significant with SBR grade (p > 0.05) and molecular subtype (p > 0.05); however, NLR was found to be significantly correlated with TNM stage (p < 0.001) and Ki-67 (p < 0.001).

Conclusion: NLR is fast emerging as a personalized theranostic marker in breast cancer. Instead of determining a generalized cut-off value, individual baseline NLR and its dynamics with disease progression will help manage patients better, obviating some of the drawbacks associated with Ki-67.