Development of ductal carcinoma of the pancreas during follow-up of branch duct intraductal papillary mucinous neoplasm of the pancreas

Background: Synchronous occurrence of intraductal papillary mucinous neoplasm ( IPMN) and ductal carcinoma of the pancreas has been reported. Branch duct IPMNs with lower likelihood of malignancy are not submitted to resection but are followed-up, so ductal carcinoma may develop during the follow-up. The development of ductal carcinoma of the pancreas during follow-up of branch duct IPMNs was investigated. Methods: 60 patients with branch duct IPMN who had an intraductal tumour of,10 mm on imaging examinations and a negative result for malignancy on cytological examination of the pancreatic juice were investigated. They were followed-up mainly by ultrasonography ( US), and additionally by endoscopic ultrasonography ( EUS), CT, magnetic resonance cholangiopancreatography ( MRCP) or endoscopic retrograde cholangiopancreatography ( ERCP) with cytological examination of the pancreatic juice for an average period of 87 months. Results: Ductal carcinoma of the pancreas distinct from IPMN developed in 5 of 60 ( 8%) branch duct IPMNs during follow-up. The 5-year rate of development of ductal carcinoma was 6.9% ( 95% CI 0.4% to 13.4%), the incidence of ductal carcinoma was 1.1% ( 95% CI 0.1% to 2.2%) per year and the standardised incidence ratio of development of ductal carcinoma was 26 ( 95% CI 3 to 48). Patients >70 years old developed ductal carcinoma significantly more frequently than those under 69. Four of five ductal carcinomas identified during follow-up were resectable. Cancer developed in IPMN in 2 of 60 ( 3%) branch duct IPMNs during follow-up. Conclusions: During follow-up of branch duct IPMNs, ductal carcinoma of the pancreas not infrequently developed distinct from IPMN. In the follow-up of IPMN, special attention should be paid to the development of ductal carcinoma of the pancreas.