Non-melanoma skin cancer: a case-control study on risk factors and protective measures

There is considerable evidence that exposure to ultraviolet radiation increases the risk of many dermatological conditions, such as non-melanoma skin cancer (NMSC). In order to better understand this relationship, we examined the connection between quantitative measures of individual sun exposure and the risk of NMSC, and the benefits of some protective measures against sunlight, analyzing the differences by sex. A case-control study was conducted in Valencia, Spain during 1990 to 1992 that included 276 cases of histologically confirmed NMSC and 552 control subjects matched by age, sex, and area of residence. Quantitative ultraviolet exposure, phenotypic features, and protective measures from sunlight were estimated by means of a history questionnaire administered by interview. Logistic regression analysis was carried out for each variable and level of quantitative measures. We observed a statistically significant increase in the risk of NMSC proportional to an increase in the hours of occupational exposure to the sun (OR = 1.2, 2.5, and 5.3, respectively). An increased risk of NMSC was observed in men with high nonoccupational exposure (OR = 1.7; p < 0.05 in open-air activities in the sun, OR = 2.1; p < 0.05 in the sun while on vacation). In women, we found instances of OR > 1, but without significance (p > 0.05). Wearing a hat at work appeared to be an important protective measure for men. Light phenotypic features predominated in our study, especially in women, and seems to be the major risk factor involved. It seems reasonable to presume that differences between the sexes are basically sociocultural, (i.e., different work activities and different use of leisure time.