A Trial of Polypodium Leucotomos in Preventing Skin Cancer and Its Precursors

Keratosis, Keratosis, Actinic, Skin Neoplasms

This proposal describes a pilot study to gather preliminary evidence of efficacy, tolerability and toxicity of oral PLE among a high-risk skin cancer population for the prevention of Actinic keratosis (AKs) and keratinocytes (KCs) to gain insight into optimal methods for recruitment, intervention development, data collection, and promoting protocol adherence prior to conducting a fully powered trial. The primary clinical outcome is AKs as measured by a clinical dermatologist, with skin cancer as a secondary clinical outcome. The investigators will also assess histologic markers of Ultra Violet (UV) damage, which have previously been shown to be reduced with oral PLE use in human studies, namely formation of UV-induced cyclo pyrimidine dimer positive cells and number of sunburn cells among epidermal keratinocytes. Results generated from this proposal will form the foundation of a fully powered clinical trial of the effect of PLE on the risk of AKs and KCs. The results may also provide information about this promising dietary supplement which may provide extra protection for a high-risk skin cancer population.

Polypodium leucotomos is a tropical fern, the extract of which has shown photoprotective effects in animal and human models, and is currently available as an over-the-counter dietary supplement. Polypodium leucotomos extract (PLE) has been shown in laboratory, animal, and clinical studies to serve as a potent antioxidant that helps mitigate UV-induced damage by scavenging free radicals and reactive oxygen species. Oral consumption of PLE in human studies has been shown to significantly reduce the number if UV-induced sunburn cells and DNA damage, and to inhibit photosensitization. Importantly, PLE appears to be exceptionally well-tolerated with no serious reported adverse side effects. PLE has been studied in numerous trials for many conditions, including skin diseases. Doses up to 1200 mg per day have been used in clinical studies, though doses for prevention of sun-damage are typically in the range of 480 mg per day. To date, no serious adverse effects have been clearly attributed to the use of PLE (this high tolerability is one of the reasons for the great interest in the clinical use of PLE). Oral consumption of other fern species, such as Polypodium vulgare, have been associated with low blood pressure and increased heart rate. On theoretical grounds, similar side effects may be possible with PLE.

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