Frequency of facial basal cell carcinoma does not correlate with site-specific UV exposure

Background: Basal cell carcinoma (BCC) is the most common type of skin cancer in whites. Long-term exposure to UV radiation is considered a major risk factor. We decided to investigate whether maximally exposed areas of the body are also the most frequent sites where BCCs develop. Design: Retrospective analysis of distribution and histopathologic features of 3065 facial BCCs. Setting: University hospital. Patients: Patients with primary or recurrent BCC of the face. Intervention: Exact topographic documentation followed by removal of BCC with Mohs prcedure and analysis of tumor extension. Main Outcome Measure: To test the hypothesis that site-specific UV exposure correlates with site-specific BCC frequency. Results: The most frequent sites of BCC were the nose (n = 1373), orbital area (n = 386), and ears (n = 269). Subdivision of these anatomical units showed that most nasal BCCs are located at the base of the nose (n = 85 1), while the apex (n = 292) and the dorsum of the nose (n = 230) were less frequent sites despite their prominent sun exposure. The shaded retroauricular fold (n = 99) and the sun-exposed preauricular crest (n = 105) were similar in frequency of BCCs; fewer BCCs were located on the helix of the ears (n = 65). Finally, almost 10 times more BCCs were found in the medial quadrant of the orbit (n = 225) than in the lateral quadrant (n = 24). No correlation between prominent UV-exposed facial contours and particular histologic features, such as solid, morpheaform, or adenoid-cystic, could be established. Conclusions: Site-specific cumulative UV exposure alone is a poor predictor of frequency or histologic features of BCC. Additional site-specific textural qualities of facial skin may be considered as potential cofactors for the development of BCC.