Incidence trends of squamous cell and rare skin cancers in the Swedish national cancer registry point to calendar year and age-dependent increases.

Little is known regarding the incidence trends of squamous cell skin carcinoma (SCC) and rare skin tumors, including Merkel cell carcinoma (MCC) and dermatofibrosarcoma protuberans (DFSP). The purpose of this study was to examine recent incidence trends for these cancers from 1990 to 2005 using the population-based Swedish National Cancer Registry. SCC incidence increased significantly over the study period and increased sharply with age. MCC incidence increased significantly for men for tumors at sun-exposed sites, and increased sharply with age. DFSP incidence was similar for sun-exposed and covered sites and decreased significantly only at exposed sites. A combination of behavioral, biological, and environmental factors likely explains the trends observed for these skin cancers.