A new U.S. study has found a link between higher levels of physical activity and lower risks for 13 different types of cancers, including three of the top four leading cancers among men and women worldwide.
The study, by a team of researchers from the National Cancer Institute, Bethesda, USA, looked at data from 1.4 million participants from 12 U.S. and European study groups who had self-reported their levels of physical activity between 1987 and 2004.
This data was then compared with the occurrence of 26 kinds of cancer, with 186,932 cancers identified in the individuals during the follow-up.
The results showed that a higher level of physical activity was associated with a lower risk of 13 of 26 cancers looked at in the study, regardless of participant's body size or smoking status, including esophageal adenocarcinoma (42 per cent lower risk); liver (27 per cent lower risk); lung (26 per cent lower risk); kidney (23 per cent lower risk); gastric cardia (22 per cent lower risk); endometrial (21 per cent lower risk); myeloid leukemia (20 per cent lower risk); myeloma (17 per cent lower risk); colon (16 per cent lower risk); head and neck (15 per cent lower risk), rectal (13 per cent lower risk); bladder (13 per cent lower risk); and breast (10 per cent lower risk).
Overall, a higher level of physical activity was associated with a 7 per cent lower risk of total cancer.
However physical activity was also associated with a 5 per cent higher risk of prostate cancer and in areas of the U.S. with high levels of solar UV radiation a 27 per cent higher risk of malignant melanoma, the most dangerous form of skin cancer.
The authors acknowledged that a big limitation of the study is that they cannot completely rule out the chance that diet, smoking and other factors may have affected the results, and the study also used participants' self-reports which can be unreliable and subjects to errors.
However the team emphasized that despite these limitations the findings still showed that physical activity could be an important way to help prevent and control cancer worldwide. Despite the many known health benefits of taking part in exercise and physical activity however, 51 per cent of people in the United States and 31 per cent of people worldwide still don't meet the recommended physical activity levels.
The results were published online in the journal JAMA Internal Medicine.