P rostate-specific antigen (PSA) is the most widely used biomarker for prostate cancer, but may also be elevated in nonmalignant conditions such as benign prostatic hyperplasia. Studies in the early 1990s suggested that rapid increases in PSA over time—a concept known as PSA velocity (PSAV)—may be useful to distinguish prostate cancer from the generally slower rise in PSA that may be seen in be...