Pancreatic cysts: can surveillance interval for small low-risk lesions be lengthened?

Background: Surveillance of pancreatic cysts are necessary due to risk of malignant transformation. However, reported progression rates to advanced neoplasia are variable and the high frequency of surveillance scans may pose a considerable burden on healthcare resources.Purpose: To validate the effectiveness of the Fukuoka Guidelines surveillance regime and determine if a longer surveillance interval can be established.Material and Methods: All magnetic resonance imaging (MRI) studies of the pancreas performed at our institution between January 2014 and December 2016 with at least one pancreatic cystic lesion and follow-up MRI or computed tomography (CT) over at least two years were reviewed for size, worrisome feature (WF), and high-risk stigmata (HRS) at diagnosis and follow-up imaging (up to year 6). Reference standards for advanced neoplasia were based on endoscopic ultrasound, fine needle aspiration cytology, or the presence of >= 2 WF or >= 1 HRS on imaging. Comparison of MRI features of progression and outcomes of diagnostic endpoints between lesions <20 mm and >= 20 mm was performed.Results: A total of 270 patients were included (201 cysts <20 mm, 69 cysts >= 20 mm). Compared with cysts <20 mm, cysts >= 20 mm were more likely to be associated with WF or HRS (40.6% vs. 12.4%; P <= 0.00001), demonstrate increase in size of >= 5 mm in two years (20.3% vs. 10.9%; P = 0.049), and develop advanced neoplasia (24.6% vs. 0.5%; P <0.00001).Conclusion: Pancreatic cysts <20 mm have a low risk of developing WF and HRS and surveillance interval may be lengthened.