Doctors Test A Pill to Protect Against Skin Cancer
October 04, 2002
Doctors at the University of Rochester Medical Center are testing whether medications known as cox-2 inhibitors, widely used now to treat arthritis, might also help protect against skin cancer. The study will involve 240 patients at eight sites around the country, including Rochester.
Candidates for the study include people who have at least 10 crusty spots known as actinic keratoses on their arms, head and neck. These come about from too much sun exposure and are prone to progress to skin cancer, and they don’t usually appear until people are in their 50s or later, after many years out in the sunshine. Actinic keratoses are rough, scaly patches, about the size of the smallest fingernail, and are usually found on sun-exposed areas like the arms, backs of the hands, nose, back of the neck and the tops of the ears.
Much of the current research on cox-2 and skin cancer is based on a previous study initiated by Alice P. Pentland, M.D., the James H. Sterner Professor and Chair of the Department of Dermatology, who published the results in Carcinogenesis in 1999. A dermatologist who specializes in the effects of the sun on skin and on skin cancer, she had noted scientific studies indicating that cox-2 inhibitors may be useful in preventing colon cancer. She decided to test the medicines against skin cancer. In a study funded by the National Institutes of Health, Pentland and her colleagues exposed two groups of mice to artificial light that mimicked the spectrum of sunlight.
After most of the mice had developed at least one tumor, half were given the cox-2 inhibitor celecoxib. After 10 more weeks, mice that received the medication developed less than half the number of tumors developed by the other animals – about 8.5 tumors each compared to 19 tumors each – and their tumors were only about one-third as large. The mice in the experiment got the same kind of skin cancer – squamous cell carcinoma– as people develop from actinic keratosis.
“We did the experiment this way because it mimics the way skin cancer really happens,” says Pentland. “You’re exposed to sunlight, but you don’t usually see a doctor about it until you develop a skin problem. It’s only then that you would normally be treated with medicine. This study showed that the medicine had an effect on the lingering effects of sun exposure, weeks after that exposure ended.”
Overall, cancer caused by sunlight accounts for about half the cancer cases diagnosed in the United States. As part of the 11-month study, some patients will receive the cox-2 inhibitor celecoxib, and others will receive a placebo. Doctors will examine the patients and compare the two groups to see if the patients taking celecoxib develop fewer subsequent actinic keratoses or whether their existing spots are more likely to shrink. Participants will be examined five times by doctors who will compare their findings to those of an automated camera system known as a melanoma monitor that will compare the number of actinic keratoses from visit to visit.
“Historically, dermatologists have mapped these spots by using such technology as placing baggies on the skin and tracing the outline of moles,” says Pentland. “We’ll still be doing this as part of this trial. But we’ll also compare new computer-vision techniques to the established methods. Perhaps there is a better way than baggies.”
Besides the University of Rochester Medical Center, patients and doctors are participating at the University of Michigan, University of California at Los Angeles, University of Alabama, Northwestern University, M.D. Anderson Cancer Center at the University of Texas, the University of Wisconsin at Madison, and Washington University in St. Louis. The principal investigator for the nationwide study is Craig Elmets, M.D., of the University of Alabama at Birmingham.
The study is funded by the National Cancer Institute and by Searle, the maker of Celebrex, the brand name for celecoxib. Anyone interested in participating should call (585) 273-4420.