High variability in anatomic patterns of cutaneous photodamage: a population-based study

Skin cancer is strongly associated with photodamaged skin but body sites are often referred to as 'exposed' or 'unexposed' to sun without recognizing extent of site-specific variation. To assess whole-body patterns of photodamage in an Australian population. A random sample of adult residents of Queensland underwent imaging across 10 body sites. Photodamage was graded from images using an ordinal photo-numeric scale. We used cluster analysis to identify whole-body photodamage patterns and prevalence proportion ratios (PPRs) to assess associated factors. Of 190 adults (median age 52; 58% males), 58% showed severe or moderate-to-severe photodamage on most body sites. A higher proportion of woman had severe photodamage on the arms (upper: p=0.002, lower: p=0.034). A higher proportion of men had moderate or severe photodamage on the lower back (p=0.004). We identified four photodamage patterns: 'severe general' (n=24, 13%), 'moderate-severe general' (n=86, 45%), 'moderate-severe head, neck, décolletage' (n=40, 21%), and 'mild-moderate upper body' (n=12, 6%). All participants with 'severe-general' photodamage were > 50 years, and more likely to have past skin cancer (PPR: 2.54, 95% CI: 1.44-4.49) than those with moderate-severe head, neck, décolletage photodamage. Those with 'moderate-severe general' photodamage showed similar associations, and were more likely female (PPR: 1.33, 95% CI: 1.04-1.69). Past or current smoking was associated with having higher levels of photodamage, with no smokers in those with 'mild-moderate upper body' photodamage. Moderate to severe photodamage across much of the body is common in Queensland adults and associated with age, sex, past skin cancer and smoking. Assuming a universal pattern of site-specific sun-exposure could lead to spurious correlations, while accurate and objective assessment of site-specific photodamage can add to understanding of the development of sun-associated skin cancers, in particular site-specific skin carcinogenesis. Additionally, degree of site-specific photodamage has the potential to assist skin cancer screening.