KLK3 and cancer: The positive patient samples were divided over the risk groups as follows: (1) heavy cigarette smoker (≥2 packets per day) more than 10 years: 12%; (2) family history of cancer: 82%; (3) chronic infection of hepatitis B virus (HBV) or hepatitis C virus (HCV): 1.5%; and (4) elevated prostate-specific antigen (PSA) level (≥4 ng/ml): 4.5%.