Ultraviolet radiation (UVR) can have a beneficial biologic impact on skin, but it is also the most significant environmental risk factor for skin cancer development. Photocarcinogenesis comprises a complex interplay between the carcinogenic UVR, skin, and the immune system. UVB is absorbed by the superficial skin layers and is mainly responsible for direct DNA damage, which, if unrepaired, can lead to mutations in key cancer genes. UVA is less carcinogenic, penetrates deeper in the dermis, and mainly causes indirect oxidative damage to cellular DNA, proteins, and lipids, via photosensitized reactions. UVR not only induces mutagenesis, altering proliferation and differentiation of skin cells, but also has several immunosuppressive effects that compromise tumor immunosurveillance by impairing antigen presentation, inducing suppressive cells, and modulating the cytokine environment. This review focuses upon molecular and cellular effects of UVR, regarding its role in skin cancer development.

Phototherapy is a valuable therapeutic tool in Dermatology, but there may be drawbacks. Acute and long-term adverse effects, of variable severity, include skin erythema, xerosis, pruritus, blistering, altered pigmentation, photoaging, and photocarcinogenesis. Despite concerns over the carcinogenic potential of ultraviolet radiation, most studies have not found an increased risk of non-melanoma or melanoma skin cancer in patients treated with ultraviolet B (broadband and narrowband) and ultraviolet A1 phototherapy. These are therefore considered reasonably safe treatment modalities concerning the development of skin neoplasms, although caution and further investigation are warranted. Photoprotective measures, such as avoidance of concurrent sunlight exposure and covering skin areas not afflicted with disease, or more modern strategies, including phytochemical antioxidants and exogenous DNA repair enzymes, can minimize the hazards of phototherapy. Patients submitted to phototherapeutic regimens should undergo complete, careful dermatologic examination regularly and lifelong.

Our results highlight the relevance of testing men who have sex with men for Neisseria gonorrhoeae at extragenital sites, regardless of the existence of local complaints. The implementation of adequate screening programmes in Portugal should be considered. We also reinforce the need to raise awareness in the population regarding the adoption of prophylactic measures against transmission of sexually transmitted infections during anal and/or oral sexual exposure.

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