KLK3 and prostate cancer: Attempts to improve the sensitivity and/ or specificity of tumor markers have led to combination of tumor markers with other procedures (e.g., combination of Carbohydrate antigen (CA) 125 with ultrasonography for early detection of ovarian malignancy) or to refining the evaluation criteria for tumor markers (e.g., PSA density or PSA velocity or age-specific PSA cut off ranges for early detection of prostate cancer).