Novel inflammation-based prognostic index for predicting survival outcomes in patients with gastric cancer

Background: We focused on the lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) and devised an inflammation-based prognostic index (IBPI) as a prognostic marker of cancer-specific survival (CSS). Methods: We reviewed the clinicopathological data of 480 patients with gastric cancer undergoing curative laparoscopic gastrectomy between January 2009 and December 2019. This study examined the significance of LMR, NLR, PLR, and IBPI as cancer-specific prognostic markers. Results: In univariate analysis, tumor diameter, histological differentiation, pathological tumor-node-metastasis (pTNM) stage, LMR, NLR, PLR, C-reactive protein (CRP) level, carcinoembryonic antigen (CEA), and postoperative chemotherapy were significantly associated with CSS. In multivariate analysis, pTNM stage and CEA were the independent risk factors for CSS, although LMR, NLR, and PLR were not the independent risk factors for CSS. The IBPI formula was constructed using hazard ratios for three inflammation-based biomarkers with worse prognosis identified in the univariate analysis: LMR < 4.315, NLR ≥ 2.344, and PLR ≥ 212.01, which were each pointed as 1, with all remaining values pointed at 0. IBPI was calculated as follows: IBPI = 2.9 × LMR + 2.8 × NLR + 2.8 × PLR. The optimal cutoff value of IBPII was 2.9. On multivariate analysis, pTNM stage, CEA, and IBPI were independent prognostic factors for CSS. In the Kaplan–Meier survival analysis, CSS in the high IBPI group was significantly worse than that in the low IBPI group. Conclusion: IBPI was devised as a novel predictive index for prognosis, and its usefulness was clarified.