Prevention of Nonmelanoma Skin Cancers
Basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs), grouped together as keratinocyte carcinomas (KCs), are the most common skin cancers, with more than 5 million diagnosed in the United States in 2012.[1] Although less aggressive than malignant melanoma and Merkel cell carcinoma, KCs comprise more than 75% of skin cancers and cause significant morbidity and billions of dollars annually in treatment expenses.[2] KC risk factors include Fitzpatrick I-II skin phototype, a history of heavy sun exposure, blistering sunburns, family history of KC, and immunosuppression.[3]
Photoprotection (protective clothing, avoidance of peak sun exposure, sunscreen application) remains the cornerstone of KC prevention. Topical retinoids, low-dose oral retinoids, and nicotinamide yield modest protection against KC in high-risk individuals but require continuous therapy.[4,5,6] In contrast, topical fluorouracil chemotherapy is highly effective at treating actinic keratoses (precursor lesions of SCC), superficial BCCs, and—off—label-SCC in situ[7] but has no established role in preventing KC.
Role of Topical Fluorouracil
To test whether topical fluorouracil could reduce the number of KCs requiring surgical treatment over a 4-year period, Weinstock and colleagues[8]enrolled 932 Veterans Affairs patients (98% men; 99% white; median age, 70 years); these volunteers were randomly assigned to apply either topical fluorouracil, 5% (n = 468) or placebo vehicle cream (n = 464) to the face and ears twice daily for 2-4 weeks.
