A nationwide study of the incidence and trends of first and multiple basal cell carcinomas in the Netherlands and prediction of future incidence.

Background: Basal cell carcinoma (BCC) is the most frequently diagnosed malignancy worldwide and an ever increasing annual incidence is observed. However, nationwide registries of BCCs are very rare, and often extrapolation of the data has been necessary to estimate the absolute number of diagnoses. As of September 2016, all histopathologically confirmed BCCs are registered in the Netherlands, due to developments in automatic notification and import in the Netherlands Cancer Registry. This offers the unique possibility to assess the nationwide population-based incidence of first and multiple BCCs.

Objectives: To assess the nationwide incidence and trends of first and multiple BCCs in the Netherlands and to predict incidence rates up to 2029.

Methods: All patients with histopathologically confirmed BCC between 2001 and 2019 were selected from the population-based Netherlands Cancer Registry. Age-standardized incidence rates were calculated and trends were analysed with use of the estimated annual percentage change. Prediction of BCC incidence rates up to 2029 was based on a regression model.

Results: In total, 601 806 patients were diagnosed with a first BCC over the period 2001-2019. The age-standardized incidence rates for both men and women with a first BCC increased over these years, from 157 to 304 and from 124 to 274 per 100 000 person-years, respectively. For male and female patients aged 30-39 years, decreases in annual incidences of -3·6% and -3·0%, respectively, were found in recent years. For patients aged 50 years or older an ever increasing trend was found. One-quarter of the patients with a first primary BCC developed one or more subsequent BCCs within 3 years. Increases in incidence of 30·4% (male) and 25·3% (female) are expected in the next 10 years.

Conclusions: BCC incidence has doubled over the past two decades. Trends have seemed to stabilize in recent years for patients aged < 50 years. This might be a first sign of a decreasing trend. The incidence continues to rise in patients aged 50 years and older. In the next decade a further increase in BCC incidence is expected.