The incredible stories that you hear are often true (stage 4 cancer remissions do occur) but usually involve selection bias. Usually it is hard to know what exactly worked, and it isn't going to work for everyone else.
If you are interested in looking more deeply into complementary cancer treatments I would recommend looking into the work of Ralph Moss.
https://paleomedicina.com/en/every-patient-that-received-my-...
I urge people who are tempted to downvote to look up "Zsófia Clemens" and "Paleomedicina", and look into the "paleolithic ketogenic" protocol. Paleomedicina is run by researchers and doctors, and they are treating many "incurable" diseases, including cancer, with a very high fat ketogenic diet based on animal foods.
The most succint explanation I have can give about how it works is that it resolves gut permeability, and puts the patient in a very ketogenic state.
I myself am in remission from multiple sclerosis with such a diet.
If you look through on of the lead researchers' Twitter feed you'll see many examples of the resistance of mainstream medical journals to even publish their case reports https://twitter.com/ClemensZsofia/status/1413029877176020994