I don't think it is code for anything, it seems they have stated the position very clearly. There are possibly no more treatment plans on the table.
As it happens, some oncos give 6 chemo sessions while others give 10 so the fact that he has managed to stay well enough to have the 6 is great; don't be sad that he is somehow missing out by not having the other 4. If he does stabilise enough to have further sessions at half dose then great but it isn't a deal breaker as the chemo will have damaged the DNA of the cancer cells already.
It seems from what you have posted that when the hormones began to fail last year, your dad became castrate resistant; that means that the cancer had learnt to feed without testosterone. Sometimes it is referred to as 'hormone independent' instead. It would be useful if you could check what he has already had; options for castrate resistant prostate cancer include:
- Radium 223 (only if he has bone mets and it is a maximum of 6 sessions)
There may be a good reason why the onco has ruled these out. It may be that he has already had the full set and they have all failed, or that the problems with kidney function, etc mean that he isn't fit enough to have them. If he had steroids last year, there is a chance that he had those with abiraterone; if the abiraterone failed, he cannot have enzalutimide so chemo may have been the last option.
Does dad have an allocated nurse? If so, you could perhaps give him/her a call and ask whether he is now moving into palliative care and if so, who makes the referral - the hospital or the GP? Hospice staff are excellent at things like pain relief, helping patients to apply for any terminal care benefits they may be entitled to, emotional support for patients and their families, most run day centres with holistic therapies, massage, etc. Basically, hospices are not just for the end stage and although your dad might still be a long way from that, there are lots of things that the palliative care team might be able to offer to make life easier for you all in the meantime.