Frequency of non‐histologically diagnosed basal cell carcinomas in daily Dutch practice

Background  Population‐based basal cell carcinoma (BCC) incidences are based on cancer registry data; however, these only include histologically diagnosed tumours. Objectives  First, to investigate the number of subsequent non‐histologically diagnosed BCC(s) in patients with a first histologically diagnosed BCC in 2004. Secondly, to observe differences in tumour characteristics between subsequent histologically and subsequent non‐histologically diagnosed BCC(s). Methods  All patients, from four hospitals located in the serving area of the Eindhoven Cancer Registry, with a first histologically diagnosed BCC in 2004 ( n  = 1290) were selected. A linkage was made with PALGA, the nationwide network and registry of histo‐ and cytopathology, to obtain pathology reports of subsequent histologically diagnosed BCC(s) up to 1 November 2010. Patient records were extracted from the participating dermatology departments and reviewed up to 1 November 2010 to identify non‐histologically diagnosed BCC(s). Results  Overall, 33.2% of the 1089 followed up patients developed subsequent histologically and/or non‐histologically diagnosed BCCs. In total, 1974 BCCs were observed of which 1833 were histologically and 141 were non‐histologically diagnosed BCCs. The distribution of tumour site and subtype differed significantly between subsequent histologically and subsequent non‐histologically diagnosed BCCs. Conclusions  The total burden of BCC is underestimated by the absence of data on the occurrence of non‐histologically diagnosed BCCs in daily dermatological practice. It is pivotal for Dutch healthcare policy makers to acknowledge this to make accurate BCC‐related cost estimates.