Can Intratumoral neutrophil lymphocyte ratio (NLR) be a prognostic biomarker in breast cancer patients?

Abstract

e12573 Background: In breast cancer patients, it is well known that the elevation of neutrophil lymphocyte ratio (NLR) in the blood are reported to associate with poor prognosis based on the notion that neutrophils represent pro-cancer, and lymphocytes represent anti-cancer immune cells. Tumor immune microenvironment has been demonstrated to play critical roles in the outcome of breast cancer patients. However, there is scarce evidence on the clinical relevance of intratumoral NLR in breast cancer patients. In the current study, we hypothesized that intratumoral NLR high tumors are associated with worse survival particularly in TNBC that is known to have high immune cell infiltration. Methods: A total of 1904 breast cancer patients’ data from METABRIC (Molecular Taxonomy of Breast Cancer International Consortium) and analyzed. NLR was calculated by the gene expressions of CD66b (CEACAM8) and CD8 (CD8A). NLR high and low were divided by the median. Overall Survival (OS) and Disease-Free Survival were calculated utilizing Kaplan Meier method between intratumoral NLR high and low groups. xCell algorithm was used to analyze the infiltrated immune cells within the tumor immune microenvironment as we have previously published. Results: Intratumoral NLR high group was associated with worse OS in whole, ER-positive/HER2-negative, and triple negative (TN) subtypes, in agreement with the previous studies. TN subtype alone demonstrated worse DFS of NLR high group. Surprisingly, gene set enrichment analysis (GSEA) demonstrated no gene set enrichment to NLR high group, which implicates that there is no distinctive mechanism that associate with worse survival. Whereas, immune response-related gene sets significantly enriched to NLR low group in TN subtype. This enrichment was consistent in ER-positive/HER2-negative. Compared with ER-positive/HER2-negative subtype, anti-cancer immune cells such as CD4+ T cells, CD8+ T cells, M1 macrophage, and helper T helper type 1 cells were significantly infiltrated in TN patients (p < 0.001 for all genes), where M2 macrophages and neutrophils were less and regulatory T cells and T helper type 2 cells were more infiltrated in TN subtype. Furthermore, intratumoral NLR was significantly lower in TN compared with ER-positive/HER2-negative subtype (p < 0.001). These results suggest that intratumoral NLR low group is associated with better survival due to favorable tumor immune microenvironment in TN subtype rather than NLR high group has worse survival. Conclusions: Intratumoral NLR low tumor demonstrated more favorable OS and more favorable DFS in TN patients. Intratumoral NLR low breast cancer was associated with enhanced immune response and higher infiltration of anti-cancer immune cells were observed in TN subtype compared to ER-positive/HER2-negative which may contribute to the favorable outcome of in TN breast cancer.