Can the Neutrophil to Lymphocyte Ratio Predict Complete Pathologic Response to Neoadjuvant Breast Cancer Treatment? A Systematic Review and Meta-analysis.

The systemic inflammatory response plays a role in tumor progression and development. The neutrophil to lymphocyte ratio (NLR) is a biochemical marker of systemic inflammation and is increasingly gaining appreciation for its prognostic role in predicting breast cancer outcomes. Previous research has demonstrated that patients who achieve a complete pathologic response (pCR) to neoadjuvant breast cancer treatment have a more favorable disease-free survival. This study aimed to assess whether the NLR can predict pCR to neoadjuvant therapy in breast cancer. A meta-analysis of 8 relevant studies was performed. The primary endpoint included pCR. Secondary endpoint included 5-year disease-free survival. Eight studies were included, reporting on 1586 patients. A total of 363 (22.88%) patients achieved pCR post neoadjuvant therapy. A lower NLR was associated with a greater rate of pCR (odds ratio, 1.83; 95% confidence interval, 1.15-2.91; P = .0003). Only 4 studies produced data on disease-free survival. A lower NLR was associated with a higher 5-year disease-free survival; however, this did not achieve statistical significance (hazard ratio, 1.38; 95% confidence interval, 0.82-2.31; P = .02). Sub-group analysis of sample size, NLR value, and geographic location proved statistically significant in determining an association between NLR and pCR. This meta-analysis found NLR to be a predictor for pCR in patients with breast cancer. All of the studies reviewed were retrospective cohort studies. Adequately sized, prospective clinical trials are needed to understand if NLR could become an important prognostic indicator of pCR.