Kylie sounds like you are the shinning star for helping your dad...some guys can't even be lead to drink water when they are thirsty...not saying he is that way.
It is not as worrisome as you are first thought even hearing the word 'cancer', most cases of prostate cancer are slower to progress and most have even decent control even with way-way worse and even with uncureable and nasty stats, compared to his= (i.e. this guy ME, been 8 yrs. and still doing well with very omnious start)..so it is possible to do way better than you likely believe and his numbers as far as we can guess herein,are towards good news versions of PCa, if you can understand that thinking.
You and he have time to study this, it probably took 10 yrs. for PCa to get to this stage, is mentioned by others...maybe very true..usually very slow growing.
Been around these types of forums for 8 yrs., seen alot of cases and information, Do Not Panic...knowledge is power...get fast track knowledge from these sources as a great start, then inform dad of the mulitple choices of possible treatments and then go see a few different types of docs that hopefully are specialists in PCa treatments get their opinoin(s) and take it further, thereafter. I actually got 8 opinions (my case was not typical and very scary), good news, insurance paid for it all, even when I fired a doc or two..like I said my case is not anywhere near typical scenario., but a few opinions for something this serious is smart. If you can show dad this stuff and get him to look at it...way better: You can look at patients histories and how they are doing later at: www.yananow.net and get a wonderful education there ASAP, so check it out.
Book: A Primer on Prostate Cancer (Dr. Strum), maybe some others, Dr. Patrick Walsh (surgery) has a good book too
Web lessons 101 and on:
www.prostate-help.org www.yananow.net www.hypertext.org www.ustoo.org (support groups and info)
Now you go....girl.. get dad's..education...is most helpful and conquers alot of fears, too.
Tell dad he has brothers at H.W. that actually give a darn and will answer about anything.