The incidence of intraductal papillary mucinous tumors of the pancreas

Purpose To review a population-controlled single institution experience with intraductal papillary mucinous tumors (IPMTs) of the pancreas treated in the United States and generate an incidence of this recently described disease process. Background First decribed in 1982, mucin-secreting pancreatic cancer constituted a newly recognized category of pancreatic exocrine tumors distinct from mucinous cystic neoplasms. Since that time, several small series of IPMTs of the pancreas have been reported. Most studies come from Asia and Europe, with limited data from American institutions and no description of the incidence. Methods The authors retrospectively reviewed all patients who underwent pancreatic resections at Madigan Army Medical Center from October 1992 through November 1999. Cases suggestive of IPMTs underwent re-examination by a staff pathologist. Clinical presentation, imaging studies, treatment, histopathology, and outcomes were reviewed for those with IPMTs. The data base of all patients eligible for care was evaluated to obtain a population denominator and determine an incidence for this neoplasm. Results Over 7 years, 78 patients underwent pancreatic resections. Forty-two had pancreatic neoplasms and, of those, 8 (19%) had IPMTs. The mean age was 67 years, with equal numbers of males and females. All patients were symptomatic (abdominal pain, 75%; jaundice, 25%; weight loss, 25%). Abnormal computed tomography scans were noted in 7/8 (88%) cases. Mucin was visualized during endoscopic retrograde cholangiopancreatography in 5/7 (71%) patients. Preoperative diagnosis of IPMT was made in 5 (62%) cases. The locations of the tumors were head (63%), tail (12%), head and body (12%), and body and tail (12%). All lesions were resectable, and procedures included 5 pancreatoduodenectomies, 2 distal pancreatectomies, and 1 total pancreatectomy. Main duct tumors were noted in 63%, whereas the remainder had both main and branch duct lesions. Tumor invasion was discovered in 2 (25%) cases. Mean follow-up was 29 months. Those without invasion were all alive (follow-up, 6 to 86 months). One patient with tumor invasion died 4 months after surgery and the other was living 20 months later. The incidence of IPMTs was 1 case/281,000 patients/year. Conclusions The incidence of IPMTs of the pancreas may be higher than previously recognized. Aggressive resection is warranted based on the favorable prognosis of patients without tumor invasion.