Why Exercise Can Slow Cancer–Maybe

Despite its name- GUT- the May issue of the International Journal of Gastroenterology and Hepatology has some seriously promising news about why, exactly, exercise may help people beat some cancers, an observation that has until now been lacking scientific explanation. Researchers at the Monash University Medical School in Melbourne,
Australia are convinced that exercise increases in a protein that
blocks cell growth and induces cell death, actions that would slow the
runaway cell growth of cancer.
We can thank ABC Science News for this prosaic, but comprehensible, version the GUT article: Researchers in Melbourne identified new cases of colorectal cancer in a prospective study of 41,528 adults recruited between 1990 and 1994. They
then looked at baseline body mass index, level of physical activity
reported and compared baseline levels of two proteins: insulin-like
growth factor binding protein-3, or IGFBP-3, and insulin-like growth
factor-1, or IGF-1. Analyses centered on 443 colon cancer patients followed for more than 5 years. Among
subjects who were physically active, an increase in IGFBP-3 was
associated with a 48% reduction in colon cancer-specific deaths. There
seemed to be no association with IGF-1.  For the physically inactive, there was no association between IGF-1 or IGFBP-3 and colon cancer survival. The researchers conclude that increased levels of IGFBP-3 with exercise blocks IGF-1’s proliferative effect on cell growth.