These comments all offer the tremendous variability in how/why, and how fast, a cancer progresses to the point of death...or not. You can only get several medical opinions from what are hopefully the "best" in their field locally...or even travel to well known facilities like Mayo Clinic, Johns Hopkins, Cleveland Clinic, UCLA, etc.
My personal experience is that my father lived to 99 years and 10 months WITH prostate cancer that was never even treated. He was too old for prostatectomy when he was finally diagnosed, but was told he had had it for at least 12-15 years, likely longer. But he suffered non-stop UTI's and hospitalizations. My maternal grandfather was diagnosed in the mid/late 1970's. He would go once per month and get a direct injection into the prostate (Lupron???). I was a young man and was never told many details. He never had the prostatectomy either, and he lived to age 96, dying from Alzheimer's, not prostate cancer. This is common enough that I have heard for decades that "if you have prostate cancer, you'll live long enough with it that you'll likely die of something else." But then, that is not always the case. I recall the father of a friend of mine. He started having lower lumbar back pain in his early '70's. He just thought he was getting old. This was in the days before there was a PSA test. He was dead within a month. The lower back pain was caused my massive lymph node invasion and metastasis throughout his pelvic area. He had ket his urination difficulties private. No one knew he had anything happening except "back pain" from being an old guy. It cost him his life. But that was the late 1970's. We've come a long WAY since then as informed patients and with incredible advancements in technology, treatment, surgery, etc.
Bottom line...you just don't know how "your" prostate cancer will compare to others. I highly recommend getting the Decipher Test though. It uses your biopsy (or surgical) prostate tissue to screen for 22 different prostate cancer-specific genes and mutations. You are given a "score" that relates to the severity of your cancer and the likelihood of progression or recurrence, plus a likely determination of likely longevity for you. Good luck.