Exercise Cuts the Risk for 13 Cancers
Written by Editor   
Tuesday, August 23, 2016 12:00 AM

Higher levels of leisure-time physical activity are associated with a significantly lower risk of developing cancer in 13 of the 26 cancers reviewed, the results of a pooled analysis of data from more than a million Europeans and Americans reveal.  That risk reduction ranged from 10% to 42%.

The affected cancers were esophageal adenocarcinoma, liver cancer, lung cancer, kidney cancer, gastric cardia cancer, endometrial cancer, myeloid leukemia, myeloma, colon cancer, head and neck cancer, rectal cancer, bladder cancer, and breast cancer.  The cancers with risk not positively affected by physical activity included those of the prostate and melanoma.

"These findings support promoting activity as a key component of population-wide cancer prevention and control efforts," say the researchers.  One commentator described the findings as “exciting,” because they "underscore the importance of leisure-time physical activity as a potential risk-reduction strategy to decrease the cancer burden in the United States and abroad."

Three mechanisms have been proposed to relate physical activity to lower cancer risk.  The first is via sex hormones. Previous studies have shown, for example, that estrogens occur in lower levels in physically active women. “The second hypothesis is related to insulin, which is that active people have lower levels of insulin, and insulin itself maybe a cancer risk factor.”  The third is connected to inflammation, with studies indicating that exercise is linked to lower levels of inflammatory markers, and that inflammation “is a general cancer risk factor."

Although it appears from the current findings that the relationship between physical activity and cancer risk is strongest for gastroesophageal and hematologic cancers, it was not possible to determine which of the hypotheses most lends itself to explaining the association.

Source:  http://www.medscape.com/viewarticle/863322