I have talked to cancer patients and treatment really violates people. You go through endless tests, get treatments with horrific side effects and basically are just treated like an object. I have heard several times that they wanted to stop treatment just because it was such a terrible experience physically and psychologically. Not sure how to do better but it’s understandable.
Even in countries that have functional medical systems, medical treatment can be very de-humanizing. It's not something that may every go away, as medical practice fundamentally clashes with most people's idea of selfhood.
Not paying exorbitant fees to pump poison in your body that makes you wish you were dead anyway. Not giving your family false hope that you will get better while looking like a stepped-on prune. The humiliation of trying experimental, unproven treatments.
At least with witch doctors, you'll keep your family somewhat calm and won't take a toll on your wallet. More inheritance for them.
"I didn't want my body to be opened... I didn't want to be violated in that way."
It's still not a good reason to avoid surgery, but it's also not a rejection of medical science.