Can the Neutrophil to Lymphocyte Ratio Predict Complete Pathological Response to Neoadjuvant Breast Cancer Treatment? Systematic Review and Meta- Analysis

Abstract Background The systemic inflammatory response plays a role in tumour progression and development. The neutrophil to lymphocyte ratio 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 pathological response to neoadjuvant breast cancer treatment have a more favourable disease-free survival. This study aimed to assess whether the neutrophil to lymphocyte ratio can predict complete pathological response to neoadjuvant therapy in breast cancer. Methods A meta-analysis of eight relevant studies was performed. Primary endpoint included complete pathological response (pCR). Secondary endpoint included five-year disease free survival. Results Eight studies were included, reporting on 1,586 patients. 363 (22.88%) patients achieved pCR post neoadjuvant therapy. A lower NLR was associated with a greater rate of pCR (OR = 1.83, 95% CI, 1.15-2.91, p=0.0003). Only four studies produced data on disease-free survival (DFS). A lower NLR was associated with a higher 5 year DFS however this did not achieve statistical significance (HR = 1.38, CI 95%, 0.82-2.31, p=0.02). Sub-group analysis of sample size, NLR value and geographical location proved statistically significant in determining an association between NLR and pCR. Conclusion This meta-analysis found NLR to be a predictor for pCR in breast cancer patients. 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.