It may be very different in America - I am in the UK, so NHS; good free treatment (well, you do pay for it in your taxes, but it is free at point of use) - but it is a bit of a conveyor belt.
As a patient you come to it in relative ignorance and learn as you go on. There is a protocol - it goes chemo - surgery (if you are lucky) - maybe radiation - more chemo, progressively less effective and with increasing collateral damage - all applied according to statistics gleaned from study after formal study.
Anything like cannabis is a bit out on its own - it isn't tested out to mainstream medicine's satisfaction, so there is a sort of conspiracy of informal approval, personal belief or disbelief and turning a blind eye; but formal, official doubt.
Patients are not told all the options. Fasting (2 days before, on the day of chemo and one day after) was something I found out about for myself - I now know it is massively effective in protecting you against the negative effects of chemo which specifically targets very active cells; your own body's cells can duck below the parapet in circumstances of perceived starvation, become less active and do only the bare minimum to keep you alive; cancer cells cannot; so they take the hit. There are good formal studies to show this is worthwhile - not one - NOT ONE - that I have seen has had a negative result. But you are never told, because it isn't mainstream.
I am also trying (with some difficulty - it is much harder than fasting) to follow the keto for cancer diet; that is, low protein, very low carbs and basically you live on fats. It works to slow the cancer - this is known. However the only dietary advice I have been given is "Eat anything you want while on chemo - sugary drinks, foods, cakes - anything to get energy into you, before nausea prevents it" - and, when I questioned this - "Some would say that sugar does feed your cancer, yes.... eat high protein" - more sensible but still wrong, as cancer can feed itself from protein too.
Against all this, I am aware that chemo has saved my life. If you like to think in military terms it is the air strike of the war against cancer - in there, zap it, try to minimise the collateral damage, whilst recognising it could be heavy - knock it to its knees so surgery can go in there and clear up. I accepted chemo thinking I was going to get surgery, but if surgery can't take every bit of the cancer that is visible, it is not carried out - "statistics suggest it is not advantageous". However, chemo - also increasingly ineffective, continues. The only choice is not to have it - no real choice as to what you have, or when. But I realise now it is not a maintenance treatment, even though it is used as such, because mainstream medicine has nothing else left. So one more session, maybe two, I think - see if it is working at all, and decide where to go from there - then onto CBD oil and keto whilst I wait for the THC.