PSA is a protein made by your prostate. Prostate cancer cells can also make PSA. If a PSA test reveals that you have high PSA levels, it could be a sign of prostate cancer. There are other conditions that can also raise your PSA, though. So elevated PSA levels are usually not enough evidence to diagnose prostate cancer on their own. A PSA level above 4 indicates about a 25% chance of having prostate cancer, and a PSA level above 10 indicates about a 50% chance of having prostate cancer.