What is the Incidence of Malignancy in Resected Intraductal Papillary Mucinous Neoplasms? An Analysis of Over 100 US Institutions in a Single Year

A subset of intraductal papillary mucinous neoplasms (IPMNs) will progress to invasive adenocarcinoma, however identifying invasive from non-invasive disease preoperatively remains challenging. The rate of malignancy in resected IPMNs in the US remains unclear. We aimed to determine the rate of malignancy and factors associated with high-risk pathology in resected IPMNs. The most recent annual cohort of patients undergoing pancreatectomy included in the American College of Surgeons National Surgical Quality Improvement Program were assessed, and contributions of demographics, preoperative laboratory values, and outcome data to level of IPMN dysplasia were analyzed. The main outcomes were incidence of invasive carcinoma or high-grade dysplasia. Of 5025 pancreatectomies in 1 year, 478 patients underwent pancreatectomy for IPMN. Invasive carcinoma/high-grade dysplasia was identified in 23% of resected lesions, and there was no difference in patient characteristics or type of resection performed in patients with invasive versus non-invasive pathology. Patients with invasive IPMNs presented significantly more often with high liver function tests, > 10% weight loss, clinical jaundice and stent placement, and were more likely to undergo an open operation (p = 0.03). There were no differences in perioperative outcomes. Adjusted logistic regression identified an association between invasive disease and non-soft pancreatic gland texture (odds ratio 0.19, 95% confidence interval 0.05-0.68, p < 0.01). Approximately 10% of all pancreatectomies in the US are for IPMNs. In these patients, treated after the revised international consensus guidelines, only 23% of IPMNs contained invasive or high-grade histology. Resections carried similar morbidity regardless of pathology. Improved biomarkers are needed to aid in surgical selection.