Obesity increases malignant risk in patients with branch-duct intraductal papillary mucinous neoplasm

Background. Obesity is an, established risk factor for pancreatic adenocarcinoma. No study has examined specifically the influence of obesity on malignant risk in patients with intraductal papillary mucinous neoplasm (IPMN), a group at substantial risk of pancreatic adenocarcinoma. We hypothesize that obesity is associated with a greater frequency of malignancy in IPMN. Methods. Data on patients undergoing resection for IPMN between 1992 and 2012 at a high-volume university institution were collected prospectively. Clinicopathologic and demographic parameters were reviewed. Patients were classified according to World Health Organization categories of body mass index (BMI). Malignancy was defined as high-grade dysplastic or invasive IPMN. Results. We collected data on 357 patients who underwent resection for IPMN. Of these, 274 had complete data for calculation of preoperative BMI and 31% had malignant IPMN: Of 254 patients with a BMI of <35 kg/m(2), 30% had malignant IPMN versus 50% in patients with BMI of >= 35 (P = .08). In branch-duct IPMN, patients with a BMI of <35 had 12% of malignant IPMN compared with 46% in severely obese patients (P = .01). Alternatively, in main-duct IPMN, no difference was found in the malignancy rate (48% vs 56%; P = .74). Conclusion. These findings suggest that obesity is associated with an increased frequency of malignancy in branch-duct IPMN. Obesity is a potentially modifiable risk factor that may influence oncologic risk stratification, patient counseling, and surveillance strategy.