Nov. 8, 2010 — A small study suggests that taking allopurinol, a drug that has been used to treat gout for more than 20 years, may reduce colorectal tumor growth and lower the risk for colorectal cancer.
Italian researchers compared three treatment groups with precancerous colorectal polyps. For up to six weeks, patients took either a placebo, 100 milligrams of allopurinol, or 300 milligrams of allopurinol, an oral drug that reduces levels of uric acid in the body. To measure effectiveness, researchers looked at levels of a colorectal cancer biomarker called Ki67 in the tissue of colorectal polyps. Among people who took a placebo, Ki67 levels increased by 70%, but they increased by 12% among people taking 300 milligrams of allopurinol and by 6% among people taking 100 milligrams of the drug.
Study researcher Andrea DeCensi, MD, director of the medical oncology unit at Galliera Hospital in Genoa, Italy, presented the study results at the Ninth Annual American Association for Cancer Research Frontiers in Cancer Prevention Research Conference held in Philadelphia.
“In the era of very expensive target therapy in oncology, it is important to search for cheap agents that could be active in cancer prevention and thus have huge public health implications,” DeCensi says in a statement.
Colorectal cancer tumors have high levels of reactive oxygen metabolites, which are critical for tumor growth. Allopurinol, sold under the brand names Lopurin and Zyloprim, reduced reactive oxygen metabolite activity. Earlier research had also shown that gout patients taking allopurinol had a lowered risk for colorectal cancer, one of the most commonly diagnosed cancers among men and women in the U.S. According to 2010 statistics from the American Cancer Society, there were an estimated 102,900 new cases of colon cancer and 39,670 new cases of rectal cancer.
Allopurinol for Colorectal Cancer
DeCensi conducted a clinical trial involving 73 patients with colorectal polyps who were treated with allopurinol between 2006 and 2010. The researchers collected samples of normal and abnormal tissue samples from the patients to compare Ki67 levels. The research team reported that allopurinol is a very safe drug and that during the study only a few side effects were reported — three mild gastrointestinal events.
Even before the study was completed, an early analysis of normal tissue samples already showed differences between patients taking a placebo and those taking allopurinol. Among the first 13 patients treated in the study, the results showed that levels of Ki67 had doubled in normal tissue in patients taking a placebo, compared with only a 5% increase in patients taking either dose of allopurinol.
Although these preliminary findings suggest allopurinol could have potential as a cancer-fighting therapy, DeCensi said the findings need to be confirmed in larger clinical trials involving more patients.