Fate of the pancreatic remnant after resection for an intraductal papillary mucinous neoplasm: a longitudinal level II cohort study.

OBJECTIVE To determine the occurrence of new disease in the pancreatic remnant after resection for intraductal papillary mucinous neoplasms. DESIGN A longitudinal level II cohort study. SETTING Virginia Mason Medical Center, Seattle, Washington. PATIENTS The primary cohort was a "resection cohort" of 203 patients who underwent partial pancreatic resection for an intraductal papillary mucinous neoplasm. MAIN OUTCOME MEASURES The occurrence rate of lesions in the pancreatic remnant after resection for an intraductal papillary mucinous neoplasm, determined by use of an annual computed tomographic scan of the pancreas. RESULTS New lesions were observed in the remnant of 17 of the 203 patients (8%) after a median follow-up of 40 months and a median interval of 38 months from the initial resection. Only 1 of these 17 patients with new lesions had a surgical margin that was positive for an adenoma at the time of resection. Comparing the 17 patients with new lesions with the 186 patients without new lesions, we found no difference in age, sex, procedure type, location in ductal system, original histology, or original margin status. In the new lesion group, no treatment was used for 12 patients who had side-branch disease detected by imaging (6% of all patients). Surgical treatment was used for 5 patients (2% of all patients): 2 with adenomas, 1 with a carcinoma in situ, and 2 with an invasive ductal carcinoma (1 with liver metastases). CONCLUSIONS We found that, following a partial pancreatic resection for an intraductal papillary mucinous neoplasm and a 40-month follow-up with an annual computed tomographic scan of the pancreas, 17 of 203 patients (8%) developed a new intraductal papillary mucinous neoplastic lesion in the pancreatic remnant. As follow-up time increases, we suspect that new lesions will constantly appear regardless of whether the surgical margin was negative at initial resection.