AFAICT, homeostatic temperature in humans does not vary by a great deal. It is 37±1°C always. I haven't come across a study where any large deviation was stated

AFAICT, homeostatic temperature in humans does not vary by a great deal. It is 37±1°C always. I haven't come across a study where any large deviation was stated. Human bodies lose heat very quickly. We evolved from a primate line which lived in South Central African plains. Our hand/feet digits are great radiators. Although still debated, our skin tone originally could have been light, much like the skin under the primate coats (with brown and African skin tones being later developments in evolution, when we started to get less furry & produced higher melatonin). So the evidence generally points in the direction that we are just another warm-blooded species without much thermal attributes. Given that, environment should show some kind of statistical difference if this cancer pathway's reliance on temperature is so pronounced. Its hard to measure, because there are several confounders in the biochemistry. It is also hard to find a body of people who have lived in both cold & hotter climates simultaneously to make direct comparisons Edit: some more details.