Although it is commonly believed that exercise helps fight, and prevent cancer, scientists have been unable to explain quite why until now. However University of Copenhagen now believe that have found a link that explains why running can reduce cancer risk and tumour growth.
They discovered that training mice regularly on a wheel (the mouse version of a treadmill) decreased the growth of multiple types of tumours, including skin, liver, and lung cancers. Furthermore, mice that exercised regularly had a smaller chance of developing cancer in the first place.
The beneficial effects of running went beyond tumor formation and growth, extending to cancer-associated weight loss, a process termed cachexia that is seen in cancer patients. Mice that exercised regularly showed no signs of cancer-associated weight loss in the researchers’ lung cancer mouse model.
The researchers say they identified several factors behind the anti-tumor effects of exercise. These anti-cancer effects are linked to the release of adrenaline (also called epinephrine), a hormone that is central to the “fight-or-flight” response. Adrenaline production is known to be stimulated by exercise.
In particular the production of adrenaline results in a mobilisation of immune cells, specifically one type of immune cell called a Natural Killer (NK) cell, to patrol the body. These NK cells are recruited to the site of the tumour by the protein IL-6, secreted by active muscles. The NK cells can then infiltrate the tumour, slowing or completely preventing its growth.
And there is no short cut injection either that works instead of running, as the researchers note that injecting the mice with either adrenaline or IL-6 without the exercise proved insufficient to inhibit cancer development, underlining the importance of the effects derived only from regular exercise in the mice.
Their conclusions of this study is published in Cell Metabolism