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.