Risk of basal and squamous cell carcinomas of the skin in Sion, Switzerland: A case-control study

Aims and background: Non-melanocytic skin cancers are the most common cance rs in white populations. Studies on populations of Anglo-Saxon and Mediterr anean origins highlighted different patterns of risk of basal-cell carcinom a and squamous-cell carcinoma in relation to sunlight exposure, skin charac teristics and phenotype susceptibility. In Sion, and in Switzerland as a wh ole, the high incidence suggests the possible presence of additional risk f actors or of a different pattern of exposure to solar radiation as well as different composition of pigmentary traits and skin sensitivity to sun. Methods and study design: We conducted a case-control study of 146 cases (7 3% of eligible cases) and 144 controls (81% of eligible subjects) to furthe r evaluate the relationship between nonmelanocytic skin cancer and risk fac tors in the Sion population. Interviews were conducted by trained interview ers with a standardized questionnaire. Results: pigmentary characteristics such as blonde and red hair as well as tendency to sunburn without tanning and number of sunburns showed a statist ically significant and independent risk increase in basal-cell carcinoma. S un exposure during recreational activities (outdoor sports) showed a risk i ncrease in basal-cell carcinoma with borderline statistical significance. A nalysis of squamous-cell carcinoma risk was limited by the small number of cases, but it was positively associated with lifetime exposure to sun durin g outdoor work and with skin characteristics. Conclusions: Results confirmed previous suggestions of a different mechanis m leading to malignant transformation of target cells from the basal and sq uamous epidermal layers, mediated by different phenotypes, and conditioning the ability to develop an effectively protective tan.