Prognostic and predictive value of neutrophil-to-lymphocyte ratio after curative rectal cancer resection: A systematic review and meta-analysis.

BACKGROUND Neutrophil-to-lymphocyte ratio (NLR) has been shown to be associated with poor prognosis in numerous solid malignancies. Here, we quantify the prognostic value of NLR in rectal cancer patients undergoing curative-intent surgery, and compare it with platelet-to-lymphocyte ratio (PLR) and lymphocyte-to-monocyte ratio (LMR). METHODS A comprehensive search of several electronic databases was performed through January 2021, to identify studies evaluating the prognostic impact of pretreatment NLR in patients undergoing curative rectal cancer resection. The endpoints were overall survival (OS), disease-free survival (DFS), and clinicopathologic parameters. The pooled hazard ratio (HR) or odds ratio with 95% confidence interval (CI) were calculated. RESULTS Thirty-one studies comprising 7553 patients were assessed. All studies evaluated NLR; thirteen and six evaluated PLR and LMR, respectively. High NLR was associated with worse OS (HR 1.92, 95% CI 1.60-2.30, P < 0.001) and DFS (HR 1.83, 95% CI 1.51-2.22, P < 0.001), and the results were consistent in all subgroup analyses by treatment modality, tumor stage, study location, and NLR cut-off value, except for the subgroups limited to cohorts with cut-off value ≥ 4. The size of effect of NLR on OS and DFS was greater than that of PLR, and similar to that of LMR. Finally, high NLR was associated with lower rate of pathologic complete response. CONCLUSIONS In the setting of curative rectal cancer resection, pretreatment NLR correlates with tumor response to neoadjuvant therapy, and along with LMR, is a robust predictor of poorer prognosis. These biomarkers may thus help risk-stratify patients for individualized treatments and enhanced surveillance.