The study found that patients taking allopurinol for at least five years experienced a two-thirds reduction in risk from colorectal cancer. "Allopurinol warrants further investigation in chemoprevention clinical trials of colorectal cancer," said Gad Rennert, M.D., Ph.D., Director of the CHS National Cancer Control Center and Technion Public Health Forum in Haifa, Israel, who led the investigation with Steve Gruber, M.D., MPH, Ph.D. from the University of Michigan, Ann Arbor.
Results were based on the analysis of 1,781 patients from Northern Israel who were prescribed allopurinol and enrolled in the Molecular Epidemiology of Colorectal Cancer (MECC) Study group between 1998 and 2004. Use of the drug was measured by a structured, in-person interview, with responses matched to computerized prescription records.
The study took into consideration other known risk factors for colorectal cancer, including aspirin or other NSAID use, first-degree family history for colorectal cancer, ethnicity, sports activity and vegetable consumption.
Allopurinol is thought to work by blocking the action of xanthine oxidase, the enzyme responsible for excess uric acid, the culprit in gout. This enzyme also produces the superoxide that promotes oxidative stress, which has been linked to DNA damage and potentially cancer. As such, allopurinol acts as an antioxidant, one of many chemicals that reduce or prevent oxidation, thus preventing cell and tissue damage resulting from free radicals in the body.
"Previous studies have focused on using antioxidants, mainly of nutritional origin, to reduce the risk of cancer," said Dr. Rennert, who
Contact: Warren Froelich
American Association for Cancer Research