My Father Had A Radical Prostatectomy 22 Years Ago. After

My father had a radical prostatectomy 22 years ago. After a few years his PSA values started to rise and he has been on hormone therapy for at least 6 years. At times, because the PSA values stayed how he was able to stop the therapy for 1/2 year at a time. This past month was the first time that the PSA values increased to 2.0 despite the hormone therapy. He also had 4 biopsies done about 3 years ago on a mass that started growing where his prostate has been. All four biopsies were negative. My question is this: could this benign mass be made up of prostate cells and since it increases (the mass) would not also the PSA values increase. Just theorhetically, could this not be an indication of cancer. I know you cannot tell me that it is not cancer, but do you think that there is a possibility that this benign growth produces PSA?