KLK3 and prostate cancer: In a Spanish study, exposure to outdoor light at night in the blue light spectrum was associated with a higher odds of prostate cancer (odds ratio [OR] = 2.05; 95% confidence interval [CI] = 1.38-3.03).83 Although new and more conservative prostate cancer screening guidelines by way of prostate-specific antigen (PSA) led to declining prostate cancer incidence rates in the late 2000s and 2010s.