Background  Dermatologists have repeatedly criticized that the public health importance of nonmelanoma skin cancers is not appropriately reflected by the patient-based cancer incidence rates of population-based cancer registries. The aims of this study were to estimate the patient incidence rates of squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and skin melanoma, and to study the effect of multiple primary skin tumors on the incidence rates.

Methods  We used a network of physicians covering a population of about 75,000 individuals to register all newly diagnosed invasive skin cancers (996 diagnoses in 796 patients), including BCC, SCC, and skin melanoma, from July 1998 to June 2003. We calculated age-standardized (world standard population) incidence rates (cases per 100,000 person-years) for the first diagnoses (called “patient incidence”) and for any diagnoses of BCC, SCC, and skin melanoma (called “case incidence”).

Results  The patient incidence rates of BCC were 63.6 in men and 54.0 in women, and the case incidence rates of BCC were 82.7 and 71.1, respectively. The patient incidence rates of SCC were 17.4 in men and 9.7 in women, and the case incidence rates were 20.4 and 10.2, respectively. The patient and case incidence rates of skin melanoma were about the same at 13.6 in men and 18.5 in women. Twenty-five per cent of the BCC patients and 14% of the SCC patients suffered from more than one BCC and SCC, respectively, during the 5-year period.

Conclusions  Patient incidence rates of BCC and SCC substantially underestimate the burden of nonmelanoma skin cancer in the population.