The value of neutrophil-to-lymphocyte ratio for response and prognostic effect of neoadjuvant chemotherapy in solid tumors: A systematic review and meta-analysis

Introduction: The neutrophil-to-lymphocyte ratio (NLR) has been found to be an indicator of poor prognosis in many tumour types. However, little is known about the relationship between the NLR and patients with tumours who receive neoadjuvant chemotherapy (NAC) in terms of response rate and prognostic ability. We thus performed this meta-analysis to further investigate this relationship. Methods: An electronic systematic literature search for articles published before September 2017 was performed to explore the association between the pretreatment NLR and outcome in patients treated with NAC. Data were extracted by the reported odds ratios (ORs) and hazard ratios (HRs) with their 95% confidence intervals (CIs) for the response rate and the survival outcome, respectively. The results were pooled using the random-effect or fixed-effect model. Results: Thirty-three studies were eventually included in our study, and all were published no earlier than 2011. An NLR that was higher than the cut-off was associated with a lower pathological complete response (pCR) rate in patients with cancer (OR = 1.72, 95% CI, 1.26-2.33). A lower NLR was associated with better overall survival (OS) (HR = 1.58, 95% CI, 1.34-1.86), cancer-specific survival (CSS) (HR = 2.22, 95% CI, 1.32-3.74), disease-free survival (DFS) (HR = 1.32, 95% CI, 1.10-1.59) and recurrence-free survival (RFS) (HR = 1.90, 95% CI, 1.50-2.40). Conclusion: Overall, an NLR lower than the cut-off value indicated a greater chance for pCR and may predict good survival outcomes after NAC for patients with solid tumours. The use of the NLR for risk stratification before NAC should be further demonstrated by future large-scale prospective studies.