Risk of pancreatic cancer in patients with pancreatic cyst

Background and Aims: Certain pancreatic cysts (mucinous cystic neoplasm and side branch intraductal papillary mucinous neoplasm [IPMN]) have malignant potential and require surveillance. However, whether patients with pancreatic cysts have a higher long-term risk of pancreatic cancer (PaCa) has still not been established. Methods: This was a retrospective study of Veterans Administration patients. Patients noted to have pancreatic cysts on CT/magnetic resonance imaging (n = 1050) were identified using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Patients aged <15 years (n = 425), patients with <1 year of follow-up (n = 13,259), and patients diagnosed to have PaCa within 1 year of identification of a pancreatic cyst (n = 102) or within 1 year of follow-up in the remaining patients in the database (n = 200) were excluded. Patients with pancreatic cystic lesions (group A, n = 755) and the remaining patients in the database without cysts (group B, n = 520,215) were followed from 1998 to 2007. Results: During the study period, in group A and B PaCa was diagnosed in 17 and 1206 patients, respectively, and the incidence rate of PaCa was 5.08 and .32 per 1000 patient-years, respectively. The hazard ratio of PaCa in all patients with cysts was 19.64 (95% CI, 12.12-31.82; P < .0001) when compared with the rest of the patients without cysts. In the subset of patients with cysts, without a history of acute or chronic pancreatitis (n = 241), the hazard ratio of PaCa (n = 5) was 18.80 (95% CI, 7.80-45.31; P < .0001). Conclusion: Patients with pancreatic cysts have a significantly higher overall risk of PaCa. The etiologic distribution of cysts in our study patients is not available. Patients with mucinous cystic neoplasm and side branch IPMN are likely to have a higher risk of PaCa than our estimation of risk based on all etiologies.