Lifetime ambient ultraviolet radiation exposure and risk of basal cell carcinoma by anatomic site in a nationwide US cohort, 1983-2005
Menée aux Etats-Unis depuis 1983 auprès de 63 912 manipulateurs en radiologie (durée moyenne de suivi : 16,9 ans), cette étude analyse l'association entre une exposition cumulée aux UV ambiants et le risque de carcinome basocellulaire (2 124 cas), par site anatomique
Background: Cutaneous basal cell carcinoma (BCC) has long been associated with ultraviolet radiation (UVR) exposure, but data are limited on risks by anatomic site. Methods: We followed 63,912 cancer-free White US radiologic technologists from cohort entry (1983-1989/1994-1998) to exit (date first BCC via 2003-2005 questionnaire). We estimated associations between cumulative ambient UVR and relative/absolute risks of self-reported BCC by anatomic location via Poisson models. Results: For incident first primary BCC in 2124 subjects (mean follow-up 16.9 years) log[excess relative risks] (ERR) of BCC per unit cumulative ambient UVR=1.27/MJ cm-2 (95% CI: 0.86, 1.68; p-trend<0.001) did not vary by anatomic site (p=0.153). However, excess absolute risks (EAR) of BCC per unit cumulative ambient UVR were large for the head/neck=5.46/MJ cm-2/104 person-year (95% CI: 2.92, 7.36; p-trend<0.001), smaller for the trunk (2.56; 95% CI: 1.26, 3.33; p-trend=0.003), with lesser increases elsewhere. There were lower relative risks, but higher absolute risks, for those with Gaelic ancestry (p<0.001), also higher absolute risks among those with fair complexion, but relative and absolute risks were not generally modified by other constitutional, lifestyle or medical factors for any anatomic sites. Excess absolute and relative risk was concentrated 5-15 years before time of follow-up. Conclusions: BCC relative and absolute risk rose with increasing cumulative ambient UVR exposure, with absolute risk highest for the head/neck, to a lesser extent in the trunk. Impact: These associations should be evaluated in other White and other racial/ethnic populations along with assessment of possible modification by time outdoors, protective, and behavioral factors.