I am 81yo and had a radial prostatectomy in September 2018. I have always had low PSA so when mine went from .9 to 2.1 over a 1 year period I wasn't alarmed. During a physical the doctor did a rectal exam and didn't like the feel of my prostate so he ordered a biopsy. It came back with Gleason score 10 and after much deliberation I decided on removal over radiation. They also removed 15 lymph nodes and one tested positive. I have since had about 6-7 PSA blood tests and all show less than .1 which they call undetectable which is the smallest that my hospital lab gives. My point is that PSA has a wide range of variability. I have a friend that has tested PSA in the teens and they are just "watching" him not concerned about cancer.