Cumulative risks and rates of subsequent basal cell carcinomas in the Netherlands
Background The incidence of multiple basal cell carcinomas (BCCs) is not well documented. Objectives To calculate the cumulative risks, rates and risk factors for the development of subsequent histologically confirmed BCCs. Methods For this cohort study the Dutch nationwide network and registry of histopathology and cytopathology (PALGA) was used. The first 2483 patients diagnosed with a first histologically confirmed BCC in the year 2004 were followed for 5 years. Multifailure survival models were used to study whether gender or age affected the risk of developing subsequent tumours. Results During our observational period, the 2483 patients developed a total of 3793 histologically confirmed BCCs. The 5-year cumulative risk of developing one or more subsequent BCCs was 29·2%. Incidence rates were 25 318 per 100 000 person-years in the first 6 months after first BCC diagnosis, decreasing to 6953 per 100 000 person-years after 5 years of follow-up. Males compared with females had a 30% [adjusted hazard ratio (HR) 1·30, 95% CI (confidence interval) 1·11-1·53] higher risk of developing multiple BCCs and those aged 65-79 years had more than 80% (adjusted HR 1·81, 95% CI 1·37-2·41) higher risk of having subsequent tumours compared with patients younger than 50 years. Conclusions The high incidence rate of subsequent BCCs among patients with a first BCC is highest in the first months after diagnosis of the first BCC but persists long term, indicating that patients with BCC should undergo full-body skin examinations at first presentation and subsequent follow-up visits. Special attention should be paid to males and persons of older age at index lesion.