More life-and-death advice from an Internet rando. I think I'll ask my doctor, who has examined me, has seen thousands of cancer patients, studied the human body, health, and cancer for decades, talks to other such experts (rather than fielding ideas on HN), ...
When you're facing a death sentence, something that "works in mice" is preferable to nothing at all.
GP didn't ask that cancer sufferers avoid existing treatment; I read it more as "Aspirin cannot possibly hurt, so you may as well".
It's like buying a lottery ticket - the negative impact of doing so is negligible but the positive impact of winning is life-changing.
Same with aspirin for cancer - the negative impact of doing so is non-existent, but the positive impact is life-changing.