There is persuasive evidence that each of the three main types of skin cancer, basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma, is caused by sun exposure. The incidence rate of each is higher in fairer skinned, sun-sensitive rather than darker skinned, less sun-sensitive people; risk increases with increasing ambient solar radiation; the highest densities are on the most sun exposed parts of the body and the lowest on the least exposed; and they are associated in individuals with total (mainly SCC), occupational (mainly SCC) and non-occupational or recreational sun exposure (mainly melanoma and BCC) and a history of sunburn and presence of benign sun damage in the skin. That UV radiation specifically causes these skin cancers depends on indirect inferences from the action spectrum of solar radiation for skin cancer from studies in animals and the action spectrum for dipyrimidine dimers and evidence that presumed causative mutations for skin cancer arise most commonly at dipyrimidine sites. Sun protection is essential if skin cancer incidence is to be reduced. The epidemiological data suggest that in implementing sun protection an increase in intermittency of exposure should be avoided, that sun protection will have the greatest impact if achieved as early as possible in life and that it will probably have an impact later in life, especially in those who had high childhood exposure to solar radiation.

The epidemiology of UV induced skin cancer.

Topical photodynamic therapy (PDT) is used to treat nonmelanoma skin cancers, such as actinic keratoses, Bowen's disease, and basal cell carcinoma (superficial and nodular). This article presents up-to-date, practical, evidence-based recommendations on the use of topical PDT using 5-aminolevulinic acid or methyl aminolevulinate for the treatment (and prevention) of nonmelanoma skin cancers. A systematic literature review was conducted (using MEDLINE), and recommendations were made on the basis of the quality of evidence for efficacy, safety/tolerability, cosmetic outcome, and patient satisfaction/preference. Topical PDT is highly effective in the treatment of actinic keratoses, Bowen's disease, superficial and thin nodular basal cell carcinomas, with cosmesis typically superior to that achieved with existing standard therapies. PDT may also be a means of preventing certain nonmelanoma skin cancers in immunosuppressed patients.

Guidelines on the use of photodynamic therapy for nonmelanoma skin cancer: an international consensus

Objective: The purpose of this article was to review the frequency, distribution, and determinants of actinic keratoses (AKs) and squamous cell carcinoma (SCC). Methods: A review of the literature was done. Results: AKs are extremely common lesions on the sun-exposed skin of Caucasian persons. The most important risk factors are a combination of genetic propensity (fair skin phenotype) and cumulative sun exposure. Their prevalence increases with advancing age. The epidemiology of SCC is virtually the same, but the lesions occur most often on the head rather than on the upper extremities where most AKs are located. AKs are the most important risk factor identifying those most predisposed to the development of an SCC. Conclusion: AKs are a reliable marker for those people most predisposed to development of an invasive SCC. In addition, AKs are probably an early stage in a biologic continuum that culminates in SCC. However, there are many more AKs than SCCs, and it is difficult to predict exactly which lesions will progress to invasive cancer.

Epidemiology of actinic keratoses and squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with over 250,000 new cases annually in the US and is second in incidence only to basal cell carcinoma. cSCC typically manifests as a spectrum of progressively advanced malignancies, ranging from a precursor actinic keratosis (AK) to squamous cell carcinoma (SCC) in situ (SCCIS), invasive cSCC, and finally metastatic SCC. In this Review we discuss clinical and molecular parameters used to define this range of cutaneous neoplasia and integrate these with the multiple experimental approaches used to study this disease. Insights gained from modeling cSCCs have suggested innovative therapeutic targets for treating these lesions.

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Åke Espmark

Papers

Ockelbo disease: epidemic arthritis-exanthema syndrome in sweden caused by sindbis-virus like agent