Significance of peripheral neutrophil-lymphocyte ratio among gastric cancer patients and construction of a treatment-predictive model: a study based on 1131 cases.

Gastric cancer (GC) is one of the most common and deadly malignancies nowadays, and inflammatory cells are closely related to tumor progression. This prospective study aims to uncover clinical significance of peripheral immune cells and build a treatment-predictive model. From July 2006 to July 2011, a total of 1131 GC patients were selected, with their general characteristics, peripheral blood and pathological parameters, and operational information obtained. The relevancies between preoperational neutrophil-lymphocyte ratio (NLR) and postsurgical pathological indexes were analyzed. SPSS 17.0 was applied in data analysis, comparing the differences of NLR between different groups using Mann-Whitney U test, contrasting the pathological differences between NLR elevated and reduced groups using Fisher test, and quantifying the correlation between post-surgical pathology and pre-operational NLR using univariate analysis. Patients were then classified into radical (applied in the training dataset) and non-radical gastrectomy (applied in the test dataset) groups, based on which we further tried to build a predictive model indicating appropriateness for radical resection using support vector machine (SVM). We found that: patients with tumor invading out of the myometrium (pT3-4) had significantly larger NLR than those with lesion limited within the myometrium (pT1-2) (P<0.05); poorly differentiated and undifferentiated malignancies were associated with higher NLR than well and moderately differentiated ones (P<0.05); there was larger NLR among patients with tumor length ≥4 cm than those <4 cm (P<0.01); preoperative NLR was significantly positively correlated with tumor TNM classification, number of metastatic lymph nodes, invasive depth and tumor size (P<0.05); larger proportion of elevated NLR was significantly associated with larger tumor size, later tumor and nodal stages, and higher TNM classification (P<0.01). We finally built a SVM model based on peripheral carcinoembryonic antigen, carbohydrate antigen 19-9, lymphocyte percentage and platelet count, effectively predicting the inappropriateness of patients undergoing curative gastrectomy when all the 4 parameters elevated with high accuracy (74.61% for the training dataset and 75.28% for the test dataset). We concluded that peripheral blood NLR indicated tumor progression, and that an efficient treatment-predictive SVM model was constructed.