Abstract
BACKGROUND: Several observational studies have suggested differences in the risk factor profile between patients with superficial basal cell carcinomas (BCCs) and non-superficial BCCs. OBJECTIVE: To test the reproducibility of previous study findings and to find new genetic and non-genetic predictors for patients with a superficial first BCC. METHODS: A total of 14.628 participants of northwestern European descent aged 45 years or older from a prospective population-based cohort study (Rotterdam Study) were linked with the Dutch Pathology Registry (PALGA) of whom 1528 were identified as BCC patients. After exclusion, 948 eligible BCC patients remained for further non-genetic analyses and 1014 for genetic analyses. We included 11 phenotypic, environmental and tumour-specific characteristics, and 20 candidate single nucleotide polymorphisms (SNP) as potential predictors for patients with a superficial first BCC. We performed binary logistic multivariable regression analyses. RESULTS: We found that patients with a superficial first BCC were significantly younger, almost two times more often female and 12-18 times more likely to have their BCC on the trunk or extremities than patients with a non-superficial first BCC. One SNP (rs12203592), mapped to IRF4, looked promising (OR 1.83, 95% CI 1.13-2.97, P-value <0.05), but after adjustment for multiple testing, no significant differences in genetic make-up between superficial BCC and non-superficial BCC patients were found. CONCLUSION: We conclude that patients with a superficial BCC differ from non-superficial BCC patients with respect to environmental factors (tumour localization as a proxy for UVR exposure) and phenotypic characteristics (age and sex), but we found no difference in genotype. As superficial BCC patients develop their first BCCs at a younger age, they could be at higher lifetime risk for subsequent skin cancers and therefore be an important group for secondary prevention.