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

Non-melanocytic skin cancers are the most common cancers in white populations. Studies on populations of Anglo-Saxon and Mediterranean origins highlighted different patterns of risk of basal-cell carcinoma and squamous-cell carcinoma in relation to sunlight exposure, skin characteristics and phenotype susceptibility. In Sion, and in Switzerland as a whole, the high incidence suggests the possible presence of additional risk factors or of a different pattern of exposure to solar radiation as well as different composition of pigmentary traits and skin sensitivity to sun.

We conducted a case-control study of 146 cases (73% of eligible cases) and 144 controls (81% of eligible subjects) to further evaluate the relationship between nonmelanocytic skin cancer and risk factors in the Sion population. Interviews were conducted by trained interviewers with a standardized questionnaire.

Pigmentary characteristics such as blonde and red hair as well as tendency to sunburn without tanning and number of sunburns showed a statistically significant and independent risk increase in basal-cell carcinoma. Sun exposure during recreational activities (outdoor sports) showed a risk increase in basal-cell carcinoma with borderline statistical significance. Analysis of squamous-cell carcinoma risk was limited by the small number of cases, but it was positively associated with lifetime exposure to sun during outdoor work and with skin characteristics.

Results confirmed previous suggestions of a different mechanism leading to malignant transformation of target cells from the basal and squamous epidermal layers, mediated by different phenotypes, and conditioning the ability to develop an effectively protective tan.