Prostate-specific antigen (PSA) is a protein made by the prostate gland. A rise in PSA is one of the first signs your cancer may be growing, but PSA levels can also be high without there being cancer, such as if you have an enlarged prostate or a prostate infection.
If you've been treated, especially if a surgeon removed your prostate, your PSA levels should be so low they can't be found on a test. The presence of any PSA after surgery is a concern.
Any rise in PSA after radiation or hormone treatment suggests the possibility the cancer is spreading. In that case, your doctor may order the same tests used to diagnose the original cancer, including a CT scan, MRI, or bone scan. The radiotracer Axumin could be used along with a PET scan to help detect and localize any recurrent cancer.
Though very rare, it's possible to have metastatic prostate cancer without a higher-than-normal PSA level.