Risk and protective factors for sporadic basal cell carcinoma: results of a two-centre case-control study in southern Germany. Clinical actinic elastosis may be a protective factor

Background There are very few data regarding sun exposure behaviour of patients with basal cell carcinoma (BCC) in central Europe. Objectives A case–control study of patients with sporadic BCC was conducted to assess the risk of occupational and leisure-time sun exposure behaviour, precursor lesions for skin cancer and phenotypic factors on the development of sporadic BCC in Ulm and Dresden, Germany. Methods A comparison was made of 213 patients with BCC (128 from Ulm, 85 from Dresden; 103 men and 110 women; median age at diagnosis 69 years) and 411 controls (237 from Ulm, 174 from Dresden; 197 men and 214 women; median age 58 years). Crude odds ratios (ORs) and corresponding 95% confidence intervals for all of 64 possible risk factors revealed strong associations in 33 items. Selection of important risk factors was performed in a multiple logistic regression. Results For sporadic BCC, an increased risk was shown for persons with actinic cheilitis (OR 7·1), actinic keratosis (OR 2·7) and solar lentigo (OR 2·5). The only phenotypic factor indicating risk of sporadic BCC was hair colour, with a higher risk for red/fair than brown/black hair (OR 4·3). There was an increased risk for persons with BCC in first-degree relatives (OR 5·1) and those with sunburn 20 years before sporadic BCC was diagnosed (OR 3·6). Additionally, occupational ultraviolet (UV) exposure appeared to be a risk factor (OR 2·4). In contrast, clinical actinic elastosis showed a protective effect (OR 0·1). Conclusions In contrast to earlier reports, clinical actinic elastosis turned out to be the only protective factor for sporadic BCC. A special relationship between wrinkling and BCC risk could not be shown. For basic research, future work should be aimed at elucidating further the different forms of collagen repair processes after intermittent and/or chronic UV exposure. The data strongly support the recommendation that a change in recreational UV exposure habits in individuals, and sunburn avoidance in particular, are necessary not only because of the increased long-term risk of melanoma, but also because of the risk of other skin cancers such as sporadic BCC.