Despite the high degree of specificity for prostatic tissue, PSA testing by itself is not highly effective as a screening tool for prostate cancer. PSA is also elevated in benign prostatic hyperplasia, which occurs with high frequency in men over the age of 50. PSA is used in conjunction with a digital rectal examination and followed by a transrectal ultrasound to provide a more sensitive and accurate diagnosis.3
The PSA cut-off value of 4.0 µg/L is widely used as a medical decision point to consider further diagnostic testing. The clinical sensitivity of PSA at a value of 4.0 µg/L is approximately 78%. Decreasing the cut-off level to 2.8 µg/L increases the sensitivity to approximately 92%, although this decreases the specificity to only 23%.4
In an effort to improve the diagnostic ability of PSA to detect early prostate cancer, one may use chronological measurements to determine the rate of change, also referred to as PSA velocity. A PSA velocity of >0.75 µg/L/year is more strongly associated with prostate cancer than benign conditions.