Ultraviolet exposure and risk of melanoma and basal cell carcinoma in Ulm and Dresden, Germany

Abstract

There is a perpetuating increase in melanoma and basal cell carcinoma (BCC) incidence in Europe. Few studies are evaluating various risk factors for both tumours. This pre-planned additional analysis directly compared occupational and past-time ultraviolet exposure behaviour, and examined the effects of sun sensitivity between melanoma and sporadic BCC, and assessed its importance for the two entities. The study included 503 patients (melanoma, n=291 and BCC, n=212), and 329 controls from Germany. In all, 244 (49%) of the cases and 165 (50%) of the controls were male (median age melanoma, 55years; BCC, 69years; and controls, 57years). Selection of important risk factors was performed by backward elimination in a polytomous logistic regression. When directly comparing melanoma and sporadic BCC, actinic elastosis (OR 48.83; 95% CI 17.87, 133.40) and site were associated with a higher risk of melanoma, whereas mountaineering in childhood, sunburn 20years before diagnosis, farming full time, sunbed use in general, seborrheic keratosis, actinic cheilitis, actinic keratosis and age were associated with a higher risk of sporadic BCC. Gardening 20years before melanoma, hair colour and solar lentigo were risk factors for both entities. A re-evaluation of the data excluding lentiginous melanoma entities (i.e. acro-lentiginous and lentigo-maligna melanoma) resulted in selection of the same factors. However, compared to controls, atopy evolved as a protective factor for melanoma (OR 0.29; 95% CI 0.15, 0.57) and BCC (OR 0.41; 95% CI 0.17, 0.99), respectively, but was associated with a higher risk of sporadic BCC compared to melanoma. The odds for having clinical actinic elastosis was lower in BCC compared to melanoma. In contrast, various factors associated with chronic UV exposure and age had higher odds for sporadic BCC, rather than melanoma. Further research is required to set the context for these findings, especially regarding, atopy in non-lentiginous vs. lentiginous forms of melanoma, and possible molecular pathways involved.