Nutraceutical strategies for alleviation of UVB phototoxicity.

Ultraviolet B exposure to keratinocytes promotes carcinogenesis by inducing pyrimidine dimer lesions in DNA, suppressing the nucleotide excision repair mechanism required to fix them, inhibiting the apoptosis required for the elimination of initiated cells, and driving cellular proliferation. Certain nutraceuticals - most prominently spirulina, soy isoflavones, long-chain omega-3 fatty acids, the green tea catechin epigallocatechin gallate (EGCG) and Polypodium leucotomos extract - have been shown to oppose photocarcinogenesis, as well as sunburn and photoaging, in UVB-exposed hairless mice. It is proposed that spirulina provides protection in this regard via phycocyanobilin-mediated inhibition of Nox1-dependent NADPH oxidase; that soy isoflavones do so by opposing NF-κB transcriptional activity via oestrogen receptor-beta; that the benefit of eicosapentaenoic acid reflects decreased production of prostaglandin E2; and that EGCG counters UVB-mediated phototoxicity via inhibition of the epidermal growth factor receptor. The prospects for practical nutraceutical down-regulation of photocarcinogenesis, sunburn, and photoaging appear favourable.

Management Pearls on the Treatment of Actinic Keratoses and Field Cancerization.

Field cancerization (FC) is a chronic disease involving multiple clinical and subclinical actinic keratoses (AK) on large photo-exposed surfaces with multifocal areas of dysplasia and precancerous changes. Patients and treatment must be properly monitored and managed to avoid aggravation and progression of the disease. Management of actinic keratoses includes lesion-directed treatments, such as cryotherapy and field-directed therapies. Field-directed therapies may have the potential to address subclinical damage, reduce AK recurrence rates and potentially reduce the risk of squamous cell carcinoma development. Multiple studies have demonstrated the efficacy of field-directed treatments, including 5-fluorouracil, photodynamic therapy, imiquimod, chemical exfoliation with trichloroacetic acid and diclofenac gel, for multiple AK and FC. The choice of therapy should be based on multiple factors, such as efficacy, tolerability, patient risk profile, costs and cosmetic results. Management of AK includes not only treatment but also prevention. Medical devices, such as sunscreens containing liposome-encapsulated DNA repair enzymes, can repair DNA damage associated with chronic UV radiation and reduce the number of new AK lesions. Here we provide therapeutic pearls and expert opinions on the treatment of AK and FC (as monotherapy or in combination) with the overall aim to achieve better, faster, and well-tolerated clinical responses.