No increased risk of breast cancer after cholecystectomy.

An increased risk of breast cancer after cholecystectomy has been proposed, but the results in different studies have not been consistent. To explore this potential association, we conducted a large, population-based, record-linkage, cohort study in Sweden. The cohort consisted of 154,283 women who had been cholecystectomized during the period 1965-1994. The cohort was followed up for breast cancer by the Swedish Cancer Register. The standardized incidence ratio (SIR), the ratio of the observed to the expected number of incident cancers derived from the entire Swedish population, estimated relative risk. During a follow-up of 31 years, we observed 3,879 cases of breast cancer in the cohort vs. 3,843 expected [SIR = 1.01, 95% confidence interval (CI) 0.98-1.04]. No significant difference in risk was observed across duration of follow-up or age at follow-up. Among women followed up for more than 20 years after cholecystectomy, the observed 403 cases of breast cancer rendered an SIR of 0.96 (95% CI 0.87-1.06). The results remained virtually unchanged after controlling for possible confounding effects of obesity and diabetes. Also, we did not find any evidence of an association between gall stone disease per se and the risk of breast cancer. We conclude that cholecystectomy and breast cancer are not likely to be associated.