Risk of pancreatic cancer after cholecystectomy: a cohort study in Sweden

Background-Although some experimental studies have indicated that cholecyst ectomy may increase the risk of pancreatic cancer, data from epidemiologica l studies are conflicting. Aims-We conducted a register based retrospective cohort study to explore th e relationship: between cholecystectomy and pancreatic cancer. Subjects-The cohort included 87 263 men and 191 049 women with a documented cholecystec tomy for cholelithiasis between 1965 and 1997. Methods-By record linkage to the nationwide and virtually complete register s of Cancer, Emigration, and Causes of Death, the cohort was followed up un til the occurrence of any cancer, emigration, death, or the end of follow u p, 31 December 1997, whichever came first. Relative risk was estimated by s tandardised incidence ratio (SIR) using the Swedish nationwide sex, age, an d calendar year specific cancer incidence rates as reference. Results-During the period of observation, 1053 cases of pancreatic cancer w ere found, among which 231 (22%) occurred within 12 months after operation. After excluding cases and person years accrued during the first two years of follow up, we observed a non-significant 6% excess risk for pancreatic c ancer, (95% confidence interval (CI) -2, to 14%). The relative risk did not increase with, increasing follow up duration, with a SIR equal to 0.98 (95 % CI 0.79-1.20) 20 years. or more after operation., Patients with a comorbi dity of diabetes or chronic pancreatitis had higher relative risks (3SIR=1. 79, 95% CI 1.39-2.28; SIR=3.17, 95% Cl 1.37-6.24, respectively). After excl uding patients with recorded diabetes, or chronic pancreatitis, the relativ e risk was close to unity (SIR=1.01, 95% CI 0.94-1.09). Conclusions-Our findings do, not support the hypothesis that cholecystectom y increases the subsequent risk of pancreatic cancer.