Population-based estimates of the occurrence of multiple vs first primary basal cell carcinomas in 4 European regions.

Objective: To estimate the population-based incidence of first and multiple basal cell carcinomas (BCCs) throughout Europe.
Design: The registry practices of 4 population-based cancer registries that routinely register BCC incidence were evaluated for inclusion of first and subsequent histologically confirmed BCCs. Where multiple BCCs were not routinely registered, comparisons with hospital databases were made.
Data Sources: Cancer registry databases from Finland, Malta, the Netherlands (Eindhoven), and Scotland were inspected for registry of first and multiple BCCs in recent years. Cross-checks with hospital and pathology databases were made to check for completeness.
Results: Age-standardized first BCC incidence rates varied between 77 (Malta) and 158 (Eindhoven) per 100 000 person-years. Generally, rates were higher in males than in females, and incidences increased steeply with increasing age. There were approximately 30% more patients with a BCC and 40% to 100% more BCC tumors diagnosed in a given calendar year than were routinely reported for patients with a first primary BCC. The difference between the number of first primary BCCs and the total number of BCCs in a calendar year was generally slightly higher for males than for females and increased substantially with increasing age.
Conclusion: Currently, routinely reported first BCC incidence rates of the included countries should be multiplied by a factor of 1.3 for an estimate of total number of patients diagnosed as having a BCC in a given year.