I Just got back from 5 days at The Mayo Clinic for my 2 year checkup. Over 2 years my PSA has gone from <.1 to .17. The MRI was negative and was scheduled for the Choline 11 Pet scan in two days. I was sweating it because even with a PSA of 0.17 you can be in real trouble. Turns out PCa tumors are heterogenic meaning they are comprised of cancer cells that make PSA and the far more aggressive cancer cells that don't produce PSA. They showed me scans of patients with PSA of .1 to 40 who were riddled with metastatic PCa because they had large amounts of PSA negative PCa. They had been monitoring their PCa with regular PSA tests and thought they were safe until they got symptoms, went for a scan and found out they were loaded with cancer or as they say lit up like a Christmas tree. You can't rely on PSA and have to get a scan at least every 2 years. I was lucky and the Choline 11 scan confirmed the MRI and gave the all clear. For what it is worth I asked about Provenge and Prostvac and was told they are both worthless.