Vulcan, great to hear your father is having a fusion biopsy. You will want to ask your doctor on number of samples that will be taken. The fusion biopsy will gather multiple samples from areas of concern (lesions), but should also gather samples randomly around the peripheral region of the prostate (prostate cancer normally forms in the peripheral regions of the prostate). In may case, additional areas of cancer were found. Please note, I am not a doctor, all of my comments are based on conversations with my doctors and online research.
I went with a radical prostatectomy - 56 years old (Gleason 7 - 4/3) and wanted to ensure most options open for future.

FYI - Johns Hopkins has a great article - 30,000+ radical prostatectomies for men with Gleason 6 (3/3) and no BCR's recorded, pretty much a "cure for those men. If your father gets pathology feedback from the biopsy that he has prostate cancer, I pray it is Gleason 6 or less. Even if it is not, there are a lot of treatments available now, as you have heard from others on this site.

Good luck,
Jim