I have had a similar experience with prostatectomy and then external radiation in 2009 right after I turned 60. My psa staid down for almost 9 years and started going up. It was 2.88 then 6 months later 6.22. Because it doubled in 6 months they had me start Lupron about 3 weeks ago and since the cancer has spread I started the Zytiga with Prednisone 5 mg daily this morning. Not sure what to expect. We were shocked that the cancer had metastasized so much with no symptoms and a low psa. My monthly cost is about $37 for both meds. My urologist and oncologist agreed that the best course for longer term is to take the treatment now rather than wait for my psa to rise again. However I won't really establish a base line until next week when they want more blood work. They will be doing a bone density test soon as a base line. Hang in there and enjoy the holidays.