Each cancer is unique to the organism. Not all cancers are death sentences. Nearly every sunburn you or I have had has been cancerous to some degree; the inflammation and reddening are your body fighting those cancers (among many other issues). Some cancers can be benign, some can be handled quite easily, some can be treated in other ways. Again, each is unique.

The data on Ketogenic diets and cancer are showing a lot of promise, but you should follow the advice of you oncologist/s. They have dedicated some portion of their lives to helping you out with your cancer. You do not want to end up in a situation where you have convinced yourself that kale is better than chemo. Again, each cancer is unique though.

Palliative care is an admission that chemo won't help and pretty much all options have been tried. At that point one can sit back and die, or try something.

Again, it depends on the situation at hand. Though ketogenic diets are showing promise, it depends on the cancer, as such diets may aggravate the cancer. One should follow the advice of the oncologist/s as well as research on their own.