Objective: This study was designed to determine the rate of recurrence and long-term survival of patients found to have a microinvasive (less than 1cm diameter) pancreatic adenocarcinoma contained within a fully resected intraductal papillary mucinous neoplasm (IPMN).Background: IPMNs are intraductal mucin-producing neoplasms of the pancreas with clear malignant potential. Published series report an incidence of invasive cancer associated with IPMN in up to 40% of patients with five year survival of 40% to 60%. These data combined with the ever growing utilization of high quality cross sectional imaging as part of routine medical evaluations and a wider knowledge of the entity has led to increased detection and surgical resection of IPMNs. An increasingly common clinical scenario is the resection of IPMNs that are thought to be benign on gross pathologic examination at the time of surgery but on microscopic examination are found to contain a small focus of invasive cancer. The rate of recurrence and associated rate of long term survival of such microinvasive cancers associated with IPMNs are not well understood.
Methods: This is a retrospective review of prospectively collected data from two academic institutions with particular expertise in pancreatic diseases. In this study, microinvasive pancreatic adenocarcinoma was defined as a focus of invasive cancer less than 1cm in diameter contained within a fully resected IPMN.
Results: Ten patients were identified meeting the inclusion criteria who underwent pancreatic resection between July 1996 and August 2007. The mean age at time of operation was 61 years and 70% were male. Pancreaticoduodenectomy was performed in 50% of patients, distal pancreatectomy in 40%, and total pancreatectomy in 10%. All had R0 resections with negative lymph nodes. At a median follow-up of 36 months, 80% of patients are alive and disease free. One patient had local recurrence of adenocarcinoma in the remnant gland 96 months following resection and is currently alive with disease at 120 months. One patient died of metastatic adenocarcinoma 23 months post-operatively.
Discussion: Some reports suggest that cancers associated with IPMNs have a better prognosis than typical pancreatic ductal adenocarcinoma. This study indicates that microinvasive cancer associated with IPMNs have an even better prognosis. These data suggest that patients with resected IPMNs (with or without associated microinvasive cancer) should undergo surveillance scans of the pancreatic remnant but that routine adjuvant chemoradiation therapy may not be indicated in this population due to the overall favorable prognosis.