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Metformin may protect patients with diabetes against intrahepatic cholangiocarcinoma

Patients with diabetes who received metformin were at reduced risk for intrahepatic cholangiocarcinoma, while biliary tract disease, cirrhosis, diabetes and smoking increased that risk in a recent study.

Researchers evaluated 612 patients with intrahepatic cholangiocarcinoma (ICC) and 594 matched controls to determine potential risk factors for the condition. All patients had been observed at the Mayo Clinic in Rochester, Minn. between January 2000 and May 2010.

Multivariate analysis indicated associations between the risk for ICC and the presence of biliary tract diseases (adjusted OR=81.8; 95% CI, 11.2-598.8), cirrhosis (aOR=8.0; 95% CI, 1.8-36.5), diabetes (aOR=3.6; 95% CI, 2.3-5.5) and smoking (aOR=1.6; 95% CI, 1.3-2.1). Sensitivity analysis that excluded a history of biliary tract disease did not significantly alter the other associations.

Among patients with diabetes, those treated with metformin were found to be at a significantly lower risk for ICC compared with diabetes patients who did not receive metformin (OR=0.4; 95% CI, 0.2-0.9). Researchers obtained similar results after sensitivity analysis incorporating patients with ICC and diabetes treated between 2006 and 2010 (n=279; OR=0.4; 95% CI, 0.1-0.9) and patients with ICC and diabetes observed between 2009 and 2010 (n=93; OR=0.3; 95% CI, 0.1-0.96).

Patients with hyperlipidemia also were found to be at decreased ICC risk (aOR=0.4; 95% CI, 0.3-0.6). While patients with hyperlipidemia treated with statins were at significantly reduced ICC risk compared with hyperlipidemia patients not receiving statins (OR=0.6; 95% CI, 0.4-0.9), researchers indicated that the apparent association may have been related to increased statin use during the evaluated period.

“Our findings are consistent with previous reports of associations between diabetes, smoking and ICC,” the researchers wrote. “The novel observation of an inverse association between metformin use and ICC risk found in our study warrants further investigation.”