[jungletime]

If this turns out to be true, then the practice through the centuries, of a "Religious Pilgrimage" might be effective too. Walking all day, with little food, would put someone in a calorie deficit, combined the stress of extraneous exercise might trigger cell death in cancer cells.

Perhaps, completely changing one's environment. Example going from a city to live in a forrest, might also trigger different genetic pathways, and awaken the immune system.

Many narrative stories have this pattern of someone getting sick and retreating, going into nature, in pursuit of fresh air or sunshine.