Work them to death.

"Preliminary indications from follow-up work in the laboratory suggest that voluntary exercise enhances UVB-induced apoptosis in the skin, and that it also enhances apoptosis in UVB-induced tumours. So, although UVB is triggering the development of tumours, exercise is counteracting the effect by stimulating the death of the developing cancer cells.

"Our studies may be the first to suggest an apoptotic mechanism for the effect of voluntary exercise in the development of cancer. In addition, we found that voluntary exercise decreased body fat and that the number of tumours decreased with decreasing amounts of fat. This effect may also play an important role in the mechanism and warrants further investigation, bearing in mind the growing rates of obesity in the Western world, particularly in the USA and UK," he said. . .

For the bowel cancer study, Dr Colbert and her co-authors used mice (APC Min mice) that had a genetic mutation that predisposed them to develop intestinal polyps. "Our studies are relevant for humans in that these Min mice have a mutation in one of the same genes, APC, that is also mutated in human colon cancer," she explained. "The protective effect of exercise and lower body weight in our mice is consistent with epidemiological evidence in humans that suggests higher levels of activity and lower body weight reduces the risk of colon cancer." . . .

"The exercising mice ran an average of 3.8 km a day, and the further they ran the fewer polyps they had. Exercise significantly reduced total polyp number and polyp size, as well as prolonging survival," said Dr Colbert. "On average there were 16 polyps per mouse in the exercising mice compared to 22 polyps in the control mice – a decrease of 25%."