Abstract
BACKGROUND AND AIMS: Mild dilatation of the main pancreatic duct (MPD) can be an early indicator of an obstructing mass, but its clinical significance in asymptomatic high-risk individuals (HRIs) undergoing surveillance has not been defined. We determined the prevalence and incidence of MPD dilation in HRI and assessed its association with neoplastic progression (to high-grade dysplasia or pancreatic ductal adenocarcinoma (PDAC)) in HRI. METHODS: We analyzed prospectively collected data from HRIs enrolled in the Cancer of Pancreas Screening cohort studies. We determined the risk of neoplastic progression associated with MPD dilation (defined as ≥4, ≥3, ≥2 mm diameter, in the head, body, tail, respectively) using Cox regression and time-varying covariate analysis. We estimated time-to-progression from baseline endoscopic ultrasound and from baseline duct dilation by the Kaplan-Meier method. RESULTS: Of 641 HRIs followed for a median 3.6 years (interquartile range 1.9-7.2), 97 (15%) had MPD dilation without evidence of an obstructing mass lesion; 10 of whom (10.3%) were diagnosed with neoplastic progression within a median of 2 years after dilation was first detected. The cumulative probability of high-grade dysplasia/PDAC in HRI with baseline MPD dilation was 16% at 5 years and 26% at 10 years. HRI with any MPD dilation were 2.6 times more likely to progress (P = .05), particularly those with ≥ 3 pancreatic cysts during surveillance (adjusted hazard ratio = 9.07, P < .001). CONCLUSION: MPD dilation without an apparent obstructing lesion is an independent risk factor for neoplastic progression in HRI.