From HBF’s expert Guest Blogger, Dr. Thomas London…
At the 2012 Digestive Disease Week meeting in San Diego, an enormous study from Taiwan was reported that encompassed almost all of Taiwan’s 23 million people. (I am indebted to Christine Frangou for her excellent report in Gastroenterology and Endoscopy News and have quoted from it extensively.) The investigators used the Taiwan National Insurance Database to identify all cases of HCC diagnosed from 1997 to 2008. There were 97,430 patients with HCC (most of whom would have had chronic hepatitis B). They were compared with 200,000 controls matched to the HCC cases by age, gender, and date of first physician visit. Using the same database they linked all patients with diabetes and their treatment methods to patients with and without HCC.
From this they were able to show that patients with diabetes had a 2.3-fold increased risk of developing HCC. In those patients who were taking metformin, however, HCC occurred about 20% less often than in those who were not treated with metformin. Furthermore, the longer patients took metformin, the lower their risk of HCC; about 7% lower for each year that they took the drug.
This study is not the final answer. We don’t know why some diabetic patients were treated with metformin and some were not. It is possible that the patients who did not take metformin had some unknown liver abnormality and were deliberately not treated with metformin. Nevertheless, anti-tumor effects of metformin in experimental animals and in cell culture systems continue to be reported. I will keep my eye out for more research on metformin and HCC and report it as it hits the medical press.
Statins are another group of drugs that are in common use. They were first approved by the FDA in 1987 to lower serum cholesterol levels and thereby prevent heart disease. Statins inhibit an enzyme in the liver used to make cholesterol. Several isolated reports suggested that statins might also help prevent HCC. This month investigators at the Mayo Clinic in Rochester, Minnesota reported a meta-analysis (a statistical method to combine results from different studies) of all the reports in the medical literature of new cases (incidence) of HCC and exposure to statin therapy. Ten studies reporting a total of 4,928 HCC cases in 1,459,417 patients were analyzed. Overall, patients who were treated with statins had a 40% lower risk of developing HCC than those who were untreated. The results varied from population to population. Asian populations which were more likely to also have chronic hepatitis B, had a 50% lower risk of developing HCC, while western populations had about a 30% lower risk.
At this time we do not know what the mechanism of a preventative effect of statins on HCC might be. Nor do we know whether statins might have been withheld from patients with high cholesterol levels because they had a liver abnormality. It is likely, however, that more information on these issues will become available in the near future. When that happens I will report it to you.