Exercise Protects Against Skin Cancer
A study found that voluntary exercise decreased body fat and that
the number of tumours decreased with decreasing amounts of fat.
During the study a female mice had 24-hour access to running wheels
and were exposed to ultraviolet B light (UVB). These mice took longer
to develop skin tumours, developed fewer and smaller tumours, and had
decreased amounts of body fat compared to mice that did not have access
to running wheels.
The second study looked at the development of pre-cancerous polyps
in the intestines of male mice and discovered that voluntary exercise
and a restricted diet reduced the number and size of polyps and
Dr Allan Conney, Garbe Professor of Cancer and Leukemia Research and
Director of the Susan Lehman Cullman Laboratory for Cancer Research at
Rutgers University, New Jersey, USA, said that programmed cell death
(apoptosis), triggered by exercise, might explain why the running wheel
mice did better.
"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."
although UVB is triggering the development of tumours, exercise is
counteracting the effect by stimulating the death of the developing
Dr Conney emphasised that it was not known yet whether exercise
decreased the risk of sunlight-induced skin cancer in humans, and
clinical trials were needed to investigate this further.
However, in bowel cancer, evidence from population studies already
suggests that physically active people have a reduced risk of
developing the disease, but the mechanisms remain unclear.