UC Irvine researchers are launching a study to determine whether a drug that prevents the development of polyps that lead to colon cancer in animals will be effective in humans.
Dr. Frank L. Meyskens, the principal investigator in the four-year study, which is being funded with $880,000 from the National Cancer Institute, said the drug difluoromethylornithine administered in very low doses has been shown to suppress 90% of colon polyps in rats and hamsters.
Meyskens, who is the director of the UCI Clinical Cancer Center in Orange, said the drug works by blocking the chemical changes that promote the growth of polyps, which can be precursors to cancer.
Yet unanswered, he said, is whether the drug will have the same effect on humans. Colon cancer is estimated to have killed 50,000 Americans this year, making it the second deadliest form of cancer, trailing only lung cancer, which was responsible for an estimated 109,000 deaths this year.
Results of a separate study conducted at the Sloan-Kettering Cancer Center in New York and published Thursday in the New England Journal of Medicine proved that removal of polyps in humans cuts the risk of colon cancer by 90%.
While surgical removal of larger polyps is one method for preventing colon cancer, Meyskens observed that it is financially unfeasible to remove all colon polyps and that preventing their growth in the first place would be more effective and economical.
He said about half of the people living in the United States who reach the age of 80 will have developed colon polyps, a small percentage of which will progress into colon cancer. The cancer, which strikes men and women equally as often, is especially prevalent in the United States and other countries with high-fat, low-fiber diets.
UCI researchers in a previous monthlong study determined the lowest safe dose of difluoromethylornithine that could be used in humans, Meyskens said. The next step, he said, is to administer the drug in low doses for a year to determine if it will suppress the biochemical levels that normally lead to polyps.
He said UCI, which is conducting the study jointly with the University of Arizona, is looking for 150 volunteers with a high risk for developing colon polyps. They must be between the ages of 50 and 69 and have had a colon polyp removed within the last five years. They must also be in good general health and plan to live in Southern California for at least the next two years.
Participants will be divided into four groups, with one group receiving a placebo and the three others receiving different low doses of the drug.
If the drug shows promise during this second-stage study, Meyskens said, UCI will apply for an additional grant to test 4,000 people over eight years.
He cautioned that “what happens in animals doesn’t always translate to humans.” He noted, for instance, that while the drug in very high doses has proven effective in treating cancer in animals, it was not proven to be an effective treatment of cancer in humans.
Moreover, Meyskens said it was found that difluoromethylornithine in high doses could temporarily impair hearing in humans. As part of the new study, he said, the hearing of participants will be closely monitored.
Anyone who would like to participate may call (714) 456-8200 beginning Monday, he said.