Association of surface ultraviolet B radiation levels with melanoma and nonmelanoma skin cancer in United States blacks.

Ultraviolet B (UVB) radiation exposure increases the risk of skin cancer in whites. Motivated by indications that United States geographic variation of relative skin cancer risk in blacks approaches that in whites, we used Poisson regression to estimate the risk of skin cancer in blacks as a function of average annual surface-levels of UVB radiation, measured by Robertson-Berger meters. United States data were used on deaths in 506 state economic areas, 1970-1994, and on incident cases in the nine areas of the Surveillance, Epidemiology, and End Results Program, 1973-1994. For black males, the age-adjusted relative risk of mortality for a 50% increase in UVB radiation was significantly above one for malignant melanoma, 1970-1994 (1.16; 95% confidence interval, 1.02-1.32) and nearly so for nonmelanoma skin cancer, 1970-1981 (1.18; 95% confidence interval, 1.00-1.39), for which the time period was chosen to avoid AIDS-related deaths from Kaposi's sarcoma. However, for black females, the relative risk of mortality was not significantly elevated for either skin cancer, and, for both black males and females, the relative risk of incidence was not significantly elevated for melanoma in the period 1973-1994. Incidence data on nonmelanoma skin cancer were not available. Although the public health implication is uncertain because of the much lower absolute risk of skin cancer in blacks compared with whites, the findings suggest that sunlight exposure increases skin cancer risk in blacks.