Background
Few data exist on the occurrence of metastatic basal cell carcinoma (mBCC).
Objective
To identify all cases of mBCC in Denmark over a 14-year period.
Methods
We searched the Danish National Patient Registry covering all Danish hospitals, the Danish Cancer Registry, the National Pathology Registry and the Causes of Death Registry during the period 1997 to 2010 for potential cases of mBCC registered according to the International classification of diseases ICD-10 and the International Systemized Nomenclature of Medicine (SNOMED).
Results
We identified 126,627 patients with a history of primary basal cell carcinoma (BCC) in the registries during the 14-year study period. Using case identifications from the four registries, a total of 170 potential mBCC cases were identified. However, after a pathology review, only five cases could be confirmed, of which three were basosquamous carcinomas. The 14-year cumulative incidence proportion of mBCC was 0.0039% (95% CI 0.0016–0.0083) among individuals with a history of previousBCC(n = 126,627) and 0.0001% (95% CI 0.0000–0.0002) in the general population.
Conclusion
MBCCis a rare disease and only a small proportion of potential cases identified in automated clinical databases or registries can be confirmed by pathology and medical record review.