Normal people have cancer cells in their bodies, and there are also some sub-healthy people who have tiny cancerous tissues in their bodies, but they are all less than clinically significant levels, a high fever can make these cancerous tissues dumped, so a high fever, means that you won't get cancer in a short period of time, which is an evil and reasonable criterion, I guess. An editor friend of mine, as fit as an ox, had a period some years ago when he had a sudden and unexplained high fever for weeks on end, so high that he had to hold the wall, and then inexplicably the fever went down again. In fact, it is entirely speculative that his immune system is the kind that is particularly sensitive to cancer (most people have a weak immune system due to the fact that cancer cells are shed from normal cells), so it may be that the development of cancer cells in the body stimulated it to come to a high fever, the cancer cells were burned by the fire of the red wall, and he returned to normal. It is impossible to test, but, it is estimated that he is a few years after this, is not going to deal with cancer.