KLK3 and prostate cancer: These limitations include the sick-quitter effect (a form of reverse causation), associative selection bias, residual confounding and measurement error (typical of all observational studies of alcohol effects), as well as detection bias (specific to prostate cancer, since prostate-specific antigen (PSA) screening is associated with health-related behaviors,12,13 and PSA itself might be affected by alcohol independently of prostate cancer).