What is PSA and why is it important?
Prostate-specific antigen, or PSA, is a biomarker you have been checking since you were diagnosed with prostate cancer. PSA can be measured through a routine blood test.

How PSMA is different from PSA
PSA and prostate-specific membrane antigen (PSMA) are both important biomarkers for you to check, and they tell you different things. Unlike PSA, which is detected through a blood test, PSMA is detected with a PSMA PET scan.

PET, positron emission tomography.
Biomarker: A characteristic of your cancer that can be measured and give your doctor more information about your cancer.
PSMA PET scan: An imaging test that allows your doctor to check for PSMA-positive (PSMA+) cancer in your body.