Solar ultraviolet B radiation compared with prostate cancer incidence and mortality rates in United States

OBJECTIVE To investigate whether the prostate cancer incidence and mortality rates in the United States correlate inversely with solar ultraviolet (UV) B radiation levels computed from a mathematical model using forecasted ozone levels, cloud levels, and elevation. Another objective was to explore whether the annual prostate cancer rates correlated more strongly with the cumulative UVB exposure for the year or for exposure during certain seasons. METHODS The age-adjusted incidence and mortality cancer rates for black and white men in the continental United States were correlated with the mean UV index values averaged for the year and for each season. RESULTS We found an inverse correlation between the UVB levels and prostate cancer incidence (R = -0-42, P < 0.01) and mortality rates (R = -0.53, P < 0.001) for white men and for incidence (R = -0,40, P < 0.05) for black men, but the strength of the correlation depended on the season of UVB irradiance. No statistically significant results for black male mortality were found. The annual prostate cancer incidence and mortality rates for white men correlated most strongly with UVB exposure levels in the fall and winter, and incidence rates for black men correlated with UVB exposure levels in the summer. CONCLUSIONS Increased solar UVB radiation might reduce the risk of prostate cancer, but the efficacy depends on the season of UVB irradiance.