F. F. Yang1, M. M. Dua2, P. J. Worth2, G. A. Poultsides3, J. A. Norton3, W. G. Park4, B. C. Visser2 1Stanford University,School Of Medicine,Palo Alto, CA, USA 2Stanford University,Hepatobiliary & Pancreatic Surgery,Palo Alto, CA, USA 3Stanford University,Surgical Oncology,Palo Alto, CA, USA 4Stanford University,Gastroenterology & Hepatology,Palo Alto, CA, USA
Introduction: Pancreatic cystic neoplasms (PCNs) are a frequent incidental finding on imaging performed for indications unrelated to the pancreas. Guidelines for management of PCNs are largely based on surgical series; important aspects of their natural history are still unknown. The purpose of this study was to characterize which PCNs can be safely observed.
Methods: A retrospective study of patients who either underwent immediate resection of a PCN (within 6 weeks of presentation) or observation with at least two imaging studies between 2004-2014 was performed. Descriptive statistics and multiple logistic regression analyses were performed to determine predictors of premalignancy and malignancy.
Results: Of the 1151 patients in this study, 66 (5.7%) underwent immediate surgery while 1085 patients had surveillance with a median follow-up of 15.5 months, mean of 24.7 (SD 25.6). Of the observed patients, 183 (16.9%) demonstrated radiographic progression, while the majority (83.1%) did not progress. Eighty-four (7.6%) of the observed patients eventually underwent surgery for concerning features with a median of 8.0 months until resection, mean of 18.1 (SD 26.1). The risk of malignancy among patients undergoing immediate surgery was 65%. The risk of developing malignancy during the first 12 months of surveillance was 5.3%, while the risk for malignancy decreases with surveillance time (TABLE).
Multiple logistic regression demonstrated that amongst all patients, jaundice (OR=36.3, CI 95%=5.96-221, p<0.0001), initial cyst size>3.0cm (OR=5.14, CI 95%=1.13-23.5, p=0.035), solid component (OR=2.96, CI 95%=1.04-8.42, p=0.042), and main pancreatic duct dilation (MPD)>5mm (OR=4.18, CI 95%=1.18-14.9, p=0.27) were independent predictors of premalignancy or malignancy. Among observed patients, jaundice (OR=13.9, CI 95%=1.48-130.3, p=0.021), unintentional weight loss (OR=8.03, CI 95%=1.59-40.5, p=0.012), radiographic progression (OR=3.42, CI 95%=1.28-7.91, p=0.004), and MPD>5mm (OR=4.99, CI 95%=1.24-20.0, p=0.023) were independent predictors of premalignancy or malignancy.
Conclusion: Relatively few pancreatic cystic lesions progress to malignancy during surveillance, especially beyond a time frame of one year. However, the risk of transformation does persist after 5 years of follow-up. This understanding of the natural history, predictors of malignancy, and especially the timeframe of transformation of PCN to either carcinoma-in-situ or invasive adenocarcinoma is important for counseling of patients undergoing surveillance.
