Welcome, this is significant, and yes, it's likely he has PCa--most american men his age have diagnoseable PC. A PSA of 170 is worrysome, to be sure. The urologist will most likely want to do a biopsy--its unpleasant but manageable. It's only with a biopsy, and a pathologist looking at the cells under a microscope, that it can be diagnosed.
I can see you're accustomed to being with him at the doctor's office, for this, take a notebook and take notes. You're going to be hit with a lot of information in a hurry, and writing it down is really important.
Try to take it a step at a time.
First, see the Urologist. He will certainly do a DRE (what we call the finger check), and likely will schedule a biopsy. After the biopsy, you'll know.
Second, assuming the biopsy report is positive for cancer, get a copy of the written report, and have the slides sent to Johns Hopkins for second opinion. And then come here and share the details of the report. We can help interpret.
Third, try to relax. PC is absolutely treatable, even at advanced stages. He'll be around a long time to come.
Fourth, like SP said above, let us know where you are. We can help aim you to top docs and treatment facilities near you.
Age at Diagnosis: 56
RALP on 2/17/15, BJC St. Louis, Dr. Figenshau
58.5g, G3+4, 20%, 4 quadrants involved
PSA 3/10/15: 0.10
My Story: www.healingwell.com/community/default.aspx?f=35&m=3300024