Home > Cancer > PSA and Risk of Prostate Cancer Spread Get the Flash Player to see this player. Rate: (Click the stars to rate) Published on Mar 28, 2011 by Jimenez, Views: 551 Prostate Cancer spreads by 3 mechanisms- local spread, lymphatics, and the blood stream. The PSA or prostate specific antigen blood test is a predictor of spread. PSA usually rises slowly with age, a rapid rise in PSA is predictive of cancer. A PSA above 20 predicts disease that has already spread. BPH, and enlarged prostate, and inflammation of the prostate, and sexual intercourse also cause a high PSA. A high Free PSA % can also predict cancer.