Body Site Distribution and Relative Tumor Density of Different Human Cutaneous Malignancies with Emphasis on Sunlight Exposure: A Single Institution Experience

Backround: Different skin cancer types display disparate body site distribution, particularly related to sunlight exposure pattern. We evaluated topographic distribution and relative tumor density (RTD) in a set of human cutaneous malignant melanoma (MM), basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) cases. Material and methods: A total of 186 MMs from 182 subjects, 1184 BCCs from 899 subjects, and 146 SCCs from 114 subjects were analyzed. Results: MMs occured most commonly on the trunk (46.8%) and upper limbs (25.3%). While the back, and the trunk in particular were sites with the most frequent MM development in males (64.3% and 45.9%), the upper limbs were the most common location in females (34.1%). BCCs and SCCs occured predominantly on the head and neck, comprising a total of 69.0% and 81.5% of the cases. The face was a region with by far the highest RTDs in BCC and SCC patients. Men had more frequently affected extra-facial sites of the head and neck compared to women in both, the BCC (46% vs 31.9%) and SCC (62.5% vs 48.3%) cases. In BCC, the second most frequent anatomic site included the back in both genders (25.1% in males, 18.2% in females), but in SCC, it represented the trunk as a whole in males (13.6%), and the lower limbs in females (14.3%). The greatest differences in RTDs between BCC and SCC were on the back (BCC:SCC ratio, 7.5:1), especially in men (BCC:SCC ratio, 9:1). Conclusion: We have observed striking heterogeneity for skin cancers risk by anatomic site with apparent gender-related disparities. Knowledge about spatial density and body site predilection of cutaneous malignancies may provide better insight into their pathogenesis and help to improve basic preventive strategies.