Association of neutrophil-to-lymphocyte ratio with clinical, pathological, radiological, laboratory features and disease outcomes of invasive breast cancer patients: A retrospective observational cohort study

Inflammatory conditions play part in the progression of malignancies, and markers signifying growth of these factors can indicate prognosis. Neutrophil-to-lymphocyte (NLR) is used as a marker of subclinical inflammation that may become an integral part of workup to indicate prognosis and associated pathology. This study aims to explore the association of NLR ratio with clinical characteristics, radiological assessment and staging, histopathology, and disease outcomes of breast cancer. A retrospective cohort study was conducted in a tertiary care center to include breast cancer patients that were diagnosed between January 2001 and December 2020. Data including tumor size, lymph nodes, metastasis, histological grading, ER/PR/HER2-neu status, molecular subtypes, clinical staging); nodal findings (sentinel and axillary); pathology from frozen section; and disease outcomes were assessed. Multivariable regression and Kaplan-Meier survival curves were employed to indicate the association of NLR with breast cancer features and disease-free survival. A total of 2050 patients had a median age of 50 years, median NLR levels of 2.14, most common pathology ductal followed by lobular, and most common site of metastasis being lungs followed by bones. Disease-free rate was 7.6%, and a recurrence rate of 1.8%, while 1.6% deaths were reported. NLR was found associated with age, treatment outcomes, tumor size, lymph nodes, metastasis and clinical staging. Other positive correlations were with Ki67 proliferation index, molecular subtypes, and tumor size on frozen section (at transverse and craniocaudal dimensions). Negative correlations were seen with estrogen and progesterone receptors. However, NLR was not found predictable of disease-free survival (P = .160). Significant predictors of disease-free survival were histological grading, ER, PR status, molecular subtype, and Ki67 proliferation index. NLR being a readily available marker has shown novel findings in its association with tumor staging, disease outcomes and characteristics of breast malignancy.