To analyze the relationship between preoperative body mass index（BMI）and long-term survival in patients with resectable gastric cancer.

The clinical data of 389 patients undergoing radical gastrectomy from January 2015 to May 2017 were retrospectively analyzed and divided into three groups according to BMI criteria，including 44 cases in the low BMI group，199 cases in the normal group and 146 cases in the high BMI group. The relationship between preoperative BMI and postoperative long-term survival of patients with gastric cancer was analyzed. SPSS 22.0 was used for data analysis，and the count data were compared by χ² test. The measurement data were represented by（

There were significant differences in gender，diabetes mellitus，number of lymph node dissection and postoperative complications among the three groups（P<0.05）. The 5-year overall survival rate of the low BMI group was significantly lower than that of the normal group and the high BMI group（44.7% vs. 77.4%，44.7% vs. 81.5%），and the difference was statistically significant （P<0.05）. There was no significant difference（P>0.05）. Univariate COX regression analysis showed that age，diabetes mellitus，tumor location，tumor diameter，degree of differentiation，pN stage，pT stage，vascular thrombolus，nerve invasion，number of lymph node dissection，BMI<18.5 kg/m² were the influential factors for long-term survival of patients with gastric cancer（P<0.05）. Multivariate analysis showed that diabetes mellitus，tumor diameter >5 cm，pT_3-4 stage，pN_2-3 stage，number of lymph nodes dissected <16，BMI<18.5 kg/m² were independent risk factors for long-term survival of patients with gastric cancer（P<0.05）.

The 5-year survival rate of patients with low BMI was lower，and there was no statistical difference between patients with high BMI and patients with normal BMI. Low BMI is an independent risk factor for long-term survival in patients with gastric cancer.