DFMO had protective effect against nonmelanoma skin cancers

Issue: November 25, 2011

AACR Frontiers in Cancer Prevention Research

An antiparasitic agent used to treat African sleeping sickness was shown to reduce incidence of skin cancer in follow-up results from a phase 3, randomized, double blind, prospective study.

In the original study, 291 men and women with a history of basal cell carcinoma or squamous cell carcinoma were assigned to 500 mg/m2 daily alpha-difluoromethylornithine (DFMO) or a placebo for 4 to 5 years. Researchers observed a significantly reduced incidence of skin cancers associated with DFMO.

In this follow-up study, Howard H. Bailey, MD, professor of medicine with the University of Wisconsin School of Medicine and Public Health, said researchers found that participants assigned to DFMO developed 163 basal cell carcinomas compared with 243 for those assigned to placebo. The annual event rate was 0.28 basal cell carcinomas per person for DFMO vs. 0.4 for placebo (P=.03).

"We found there is still evidence that the men and women assigned to DFMO for 5 years continued to have a lower incidence of nonmelanoma skin cancers compared with people assigned to placebo," Bailey said in a press release. "What we saw was that the presumed benefit that people got in taking DFMO appeared to persist for years after stopping it."

The results were presented at the 2011 AACR International Conference on Frontiers in Cancer Prevention Research.

DFMO did not appear to have a similar protective effect against squamous cell carcinoma. Researchers observed 95 squamous cell carcinomas in the DFMO group compared with 115 in the placebo group. Annual event rate for DFMO was 0.15 squamous cell carcinomas per person compared with 0.19 for placebo (P=.56).

DFMO was associated with few adverse events. Some patients developed ototoxicity, but that did not lead to a "noticeable reduction in hearing," 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."

For more information:

Lamont S. #A52. Presented at: 10th AACR International Conference on Frontiers in Cancer Prevention Research; Oct. 22-25, 2011; Boston.

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