Background/AimsWe investigated the effect of preoperative malnutrition on postoperative surgical outcomes in elderly patients undergoing pancreatoduodenectomy for periampullary neoplasms.MethodsThis prospective cohort study enrolled 154 patients aged ≥65 years with periampullary neoplasms. Using the Mini Nutritional Assessment tool, patients were categorized into three groups according to their preoperative nutritional status: well-nourished (13.0%), at-risk-of-malnutrition (59.7%), and malnourished (27.3%).ResultsSignificant intergroup differences were observed in preoperative body mass index (25.6±2.4 kg/m2 [well-nourished] vs 23.4±2.6 kg/m2 [at-risk-of-malnutrition] vs 21.1±2.8 kg/m2 [malnourished], p<0.001). The overall morbidity significantly differed between the well-nourished and malnourished groups (20% vs 50.0%, p=0.024). The rates of clinically significant postoperative pancreatic fistula were significantly different among groups (p=0.035). Univariate and multivariate analyses showed that the at-risk-of-malnutrition or malnourished status (hazard ratio [HR], 3.45; p=0.037) and intraoperative blood loss (HR, 1.01; p=0.040) significantly affected the overall postoperative morbidity in elderly patients.ConclusionsBefore surgery, 87.0% of patients were classified into the at-risk-of-malnutrition or malnourished group. Compared with well-nourished patients, patients with nutritional issues showed a higher overall surgical morbidity. Improved preoperative nutritional status leads to favorable surgical outcomes in elderly patients.