Sorry about your Dad and equally sorry for you as cancer is a strain on everyone associated with the person who has it so it's ok to have the same emotions ( from a different perspective) as your Dad has.
I was diagnosed 21 months ago, then aged 49' Gleason 9 T4n1m1a spread to my lymphs. Like your dad I was put on hormone treatment and then docetaxl (I only had 6 doses as my onco said no evidence that 10 was better so I would ask the onco next time you see him/her). Early chemo is a new thought, research now shows that chemo within 3 months of diagnosis of advanced prostate cancer gives on average an EXTRA year than before so it's great your dad is getting that.
After the initial emotion of "I have got effectively terminal cancer" I just got on with it. Chemo was ok, I felt a bit sick after the first and they said just take the anti sick pills for 6 days rather than 3. I did this for every session thereafter and never felt sick again. Some people say suck frozen pineapple cubes to preserve taste buds, I did this the first time but it was hassle and whilst my taste buds did dull a bit for a couple of months they came back later just as before.
I guess at this stage it is worth saying what chemo does as it was never explained to me but once I knew the below it all made sense. So in lay mans terms chemo damages fast growing things like cancer, but it also damages other fast growing things too so the things that your dad may also get are , damaged taste buds, hair loss, finger and lesser toe nail weakness, numb soles of feet and fingers, cracking skin around finger nails, nose bleeds (I used to wake up every morning with dried blood in my jose but never had a nose bleed as such), a black tongue (this only happened once on day 3 after the first chemo, it went normal again after about 7 days and remained so for the rest of treatment. All the above were manageable and slightly annoying at worst, they all went back to normal apart from numb feet which I still have but mildly.
Your dad will also have a low immune system however that does not mean he needs to be a recluse but just avoid known bacteria things like anyone with chicken pox, anyone with a cold, swimming pools. I was only recently told that it is possible that all the immune system that we build up over years could be damaged so I had booster jabs for things like polio, tetanus etc. I was also told I could get chicken pox again so make a note for after chemo to raise boosters with his GP in say 6 months time.
My first chemo was too high a dose (they want to be as high as possible without killing you!) so before my second session I was given some self administered injections to stimulate my bone marrow. After the second one I had a bad reaction and my temperature soared. I ended up in a&e in so much pain and on antibiotics as I reacted badly to the jabs so thereafter I had a lower dose and was ok for the rest of the treatments.
I used to run a bit and decided on the day after my first chemo that I would carry on. I ran 2 marathons on week 13 and 15 of chemo which goes to show that a lot of what one does is in the mind as it would have been so easy to stay in bed for the duration of chemo.
I was given 6 weeks of radiotherapy at the end of chemo on my prostate as again my onco said there was some evidence that zapping the moth ship of PSA even once it had spread can reduce the rate of growth thereafter. The radiotherapy was a breeze but 6 months later I had bleeding bowels from collateral damage called radiation proctitis . Not painful but a bit worrying at first. I was given suppositories to sort but they didn't work so I stopped taking them and resigned myself that I would just have this forever.
As for the outcome, well my PSA was 342 on diagnosis , after chemo and then radiotherapy it went down to 0.5 so the stuff works. Later my PSA rose to 4 quite quickly and they started me on Abirateone in Jan this year, that is doing a great job and my PSA is now 0.3
I changed my diet quite a lot, at home I am effectively a vegan who eats fish it no dairy, meat or eggs but when I eat out I do what I want as I doubt 2 meals a week involving dairy or meat will be what finishes me off!
I also take some supplements, pomi-t, turmeric plus a baby asprin and vitamin d. My onco said that the last two should be a must for every human regardless of cancer. The vitamin d between September and April I've when the sun is not high enough and we are not outside enough to get the benefit. I also drink green tea.
More recently I have been having acupuncture to reduce the hot flushes that the hormone treatment gives me and also started on some mysterious powder that is Chinese medicine plus powdered reishi mushrooms. The guy I see is an expert in Chinese medicine for cancer patients. I told him all my issues and he got the powder made up for me. All I can say is that within a week my proctitis stopped and I feel better than ever. Most people on this site have a view as to what may work, some more extreme than others. I can't guarantee any of the above does anything but I feel better about doing something and in the last 21 months I have not had a cold or been ill in any way apart from what I have said above. I have also run some massive races accross the Sahara and around the uk.
As for prognosis, I was told 2 to 10 years but think 3 to 4. Statistically only 30% of men survive 5 years after diagnosis of advanced prostate cancer HOWEVER all those stats are based on historic data is before early chemo, before widespread use of Abirateone etc so whilst I may be unlucky and not beat the average I live every day to the best of my ability and will cross whatever bridges I need to if I need to, don't get me wrong, I know the bridges are there but who knows maybe I will find another way.
I hope the above gives you some comfort that it's not all doom and gloom, you must look after yourself as you are key to supporting dad even by phone, I promise you the best thing you can do for dad is call him every day, don't fuss over his situation but tell him what you are doing and say you love him now and again as that kind of stuff means more to me (and I therefor guess to him) than ever, I want to know my kids are heading in the right direction although mine are younger at 11, 16 and 18.
Keep posting, ask questions of us and of the onco as we all welcome the experience of various doctors, best wishes and good luck for your dad , Kev