Sleeping Sickness Drug May Provide Long-Term Protection Against Skin Cancer
- Significant difference found in the prevention of basal cell carcinoma.
- Trend found in prevention of squamous cell carcinoma, although not significant.
- No evidence of adverse effects found up to 10 years after being assigned to the drug.
BOSTON — An antiparasitic agent used to treat African sleeping sickness might someday be used to prevent nonmelanoma skin cancers. Researchers found that DFMO, or α-difluoromethylornithine, still appeared to protect against nonmelanoma skin cancers years after people stopped taking the drug, according to a poster presented at the 10th AACR International Conference on Frontiers in Cancer Prevention Research, held Oct. 22-25, 2011.
In this follow-up study, researchers evaluated prolonged evidence of a protective effect of DFMO among 209 people who had participated in an earlier study. The researchers also wanted to ensure there were no obvious deleterious effects associated with the drug, according to Howard H. Bailey, M.D., professor of medicine, and study presenter Sarah Lamont, a medical student, both from the University of Wisconsin School of Medicine and Public Health.
The original study was a phase III, randomized, double-blind, prospective study of 291 men and women with a history of nonmelanoma skin cancer. They were assigned to either DFMO or a placebo for four to five years. At the end of the study period, researchers found a reduced skin cancer incidence among those assigned to DFMO.
“We showed a significant protective effect against basal cell carcinoma, but not a significant amount of protection against squamous cell carcinoma of the skin,” Bailey said.
The main side effect was a slight ototoxicity that was found on testing, but this was not associated with a noticeable reduction in hearing by the subjects.
In the current retrospective study, researchers reviewed the electronic medical records of 209 of the original participants to establish cancer rates and to see if any other illnesses they might have developed could be attributed to DFMO.
“We found there is still evidence that the men and women assigned to DFMO for five years continued to have a lower incidence of nonmelanoma skin cancers compared with people assigned to placebo,” Bailey said. “What we saw was that the presumed benefit that people got in taking DFMO appeared to persist for years after stopping it.”
Study limitations include that participants may have been followed differently or changed their behaviors to limit sun exposure because of being in the original study, Bailey said.
“Our data suggest that the protective event that we saw in our prospective study appears to continue and there was no evidence of any rebound effect,” he said. “We did not find any evidence that the people who received DFMO were harmed [other than the original ototoxicity].”
However, Bailey cautioned, more studies are needed before DFMO can be recommended as a prophylaxis against nonmelanoma skin cancers.
He added that such prophylaxis measures are needed because public health efforts to teach people about limiting sun exposure have not resulted in fewer cases of skin cancer, with more than 2 million cases of nonmelanoma skin cancer diagnosed each year. “The incidence continues to rise despite public health efforts to get people to lessen their sun exposure,” Bailey said.
The study was sponsored by the University of Wisconsin Carbone Cancer Center and the University of Wisconsin School of Medicine and Public Health.
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, the AACR is the world’s oldest and largest professional organization dedicated to advancing cancer research. The membership includes 33,000 laboratory, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants, research fellowships and career development awards to young investigators, and it also funds cutting-edge research projects conducted by senior researchers. The AACR has numerous fruitful collaborations with organizations and foundations in the U.S. and abroad, and functions as the Scientific Partner of Stand Up To Cancer, a charitable initiative that supports groundbreaking research aimed at getting new cancer treatments to patients in an accelerated time frame. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special Conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care, and Educational Workshops are held for the training of young cancer investigators. The AACR publishes seven major peer-reviewed journals: Cancer Discovery; Cancer Research; Clinical Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Prevention Research. In 2010, AACR journals received 20 percent of the total number of citations given to oncology journals. The AACR also publishes Cancer Today, a magazine for cancer patients, survivors and their caregivers, which provides practical knowledge and new hope for cancer survivors. A major goal of the AACR is to educate the general public and policymakers about the value of cancer research in improving public health, the vital importance of increases in sustained funding for cancer research and biomedical science, and the need for national policies that foster innovation and the acceleration of progress against the 200 diseases we call cancer.
In Boston, Oct. 22-25, 2011: