BACKGROUND: D2 lymph node dissection in gastric cancer is controversial in Western countries because of the relatively high complication and mortality rates. The purpose of this study was to clarify the effects of fat volume on operation factors, postoperative complications, and survival in gastric cancer surgery.METHODS: We studied 293 consecutive patients who had undergone distal gastrectomy with D2 dissection for gastric cancer at our hospital between 1990 and 1997. The patients were classified into three groups according to their body mass index (BMI; kg/m(2)). We analyzed differences in the operation time, the amount of blood loss, the postoperative complications and the survival rate among the three groups.RESULTS: Group A patients had a BMI of less than 20 ( n = 61), group B had a BMI of 20-25 ( n = 178), and group C had a BMI of more than 25 ( n = 54). There were significant differences in operation time (group A, 206 +/- 66 min; group B, 226 +/- 61 min; group C, 252 +/- 61 min; P < 0.05), blood loss (group A, 417 +/- 282 ml; group B, 501 +/- 295 ml; group C, 605 +/- 333 ml; P < 0.05), and postoperative complications (group A, 3.3%; group B, 5.6%; group C, 22.0%). There were significant differences in postoperative complications between groups A and C, and between groups B and C. However, the difference between groups A and B was not significant, and no significant difference in survival rate was seen among the three groups.CONCLUSION: Fat volume definitely increases the postoperative complications. Accordingly, the high rate of postoperative complications of D2 surgery in Western countries may be related to the patients' relative obesity.