Evaluating the effect of diabetes on the prognosis of gastric cancer using a propensity score matching method.

Background Gastric cancer (GC) is one of the malignant tumors with high incidence in China. At present, the relationship between type 2 diabetes (T2DM) and the therapeutic effect of various malignant tumors has attracted more and more attention. This study aimed to investigate whether T2DM is a prognostic factor for patients with GC. Methods Patients who had GC and who were admitted to our hospital from November 2008 to December 2015 were included in the study. Among these patients, 84 patients GC complicated with T2DM (GC + T2DM) were enrolled in the observation group, and 215 patients with normal blood glucose were enrolled in the control group. Patients' general information was collected by referring to their electronic and paper medical records, and their living status was followed up by conducting a telephone survey, referring to their hospitalization record, and performing an outpatient review. A propensity score matching method was used to select a 1:1 matched control for each patient with GC and diabetes. An overall survival curve was established using the Kaplan-Meier method. The survival rate was compared via a log-rank test. A Cox proportional hazards regression model was used to the analyse single and multiple factors affecting patient outcomes. Results Before matching was conducted, the differences in gender, stage, treatment, and comorbidity were found to be statistically significant (P>0.05). After matching was completed, the clinical data and pathological differences between the two groups were not statistically significant (P<0.05). A histogram matching the pre- and post-propensity scores showed that the matching was successful. The results of the Cox regression model revealed that grouping, pathological type, and treatment were the independent risk factors of the survival of patients with GC. Survival analysis found that the 3-year, 5-year, and overall survival rates of the observation group were significantly lower than those of the control group (P<0.05). Conclusions T2DM plays an important role in the development of GC, and is a prognostic factor among patients with GC.