Difluoromethylornithine (DFMO) and nonsteroidal anti-inflammatory drugs have been shown to have a synergistic protective effect against colon cancer. As single agents, both DFMO and diclofenac have demonstrated efficacy in the treatment of actinic keratoses, the cutaneous precursors to cutaneous squamous cell carcinomas. We designed a study investigating the effects of these two medications, alone and in combination, on sun-damaged skin of the forearm. The primary objective is to determine whether a three-month course of combination therapy increases the efficacy over either agent used alone in the treatment of moderately sun-damaged skin. The primary endpoint is the change in karyometric values from skin biopsies before and after treatment. A total of 156 subjects were enrolled in the study and randomized to A: topical DFMO applied BID × 90 days; B: topical diclofenac applied QD × 90 days; or C: topical DFMO applied BID and topical diclofenac applied QD × 90 days. Planned sample size was 138 evaluable subjects to provide 80% power to detect the difference in response rate as measured by karyometric average nuclear abnormality (ANA) between the single-agent DFMO arm and the combination treatment arm at the 2.5% significance level. The results for efficacy and safety will be presented at the AACR Frontiers in Cancer Prevention meeting. Secondary biomarker and clinical endpoints will also be summarized. These findings will provide insight into the potential use of the combination of these medications as skin cancer chemopreventive agents.

Citation Information: Cancer Prev Res 2010;3(12 Suppl):CN02-06.

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2010