A new medical research has confirmed the fact that exercise can cut the risk of colon cancer for both men and women by 25 per cent.
Colon Cancer, also known as Colorectal cancer, or large bowel cancer, is the third leading cause of cancer in men and the fourth leading cause of cancer in women, according to the World Health Organization The disease originates with adenomatous polyps in the colon. These mushroom-like growths are usually benign at the beginning, but can turn into cancerous over the time.
Looking at over 50 studies going back to the 1980's the authors of the study lead by Dr. Kathleen Y. Wolin of the Siteman Cancer Center at the Barnes-Jewish Hospital and the Washington University School of Medicine in St. Louis Missouri, found that the link between physical activity and colon cancer was underestimated.
The researchers restricted their analysis to case-control or cohort studies (both types of observational study) where information only for colon cancer was available. Colon cancer occurs in the upper part of the large bowel, so the researchers left out studies that examined rectal (lower large bowel) cancers, or both colon and rectal cancers together, because no link between exercise and rectal cancer was shown in previous studies. The present data shows that such a link is unlikely to exist. Two-thirds of bowel cancer cases occur in the colon, while the rest develop in the rectum.
After that, the scientists recorded all the details about each study, and assessed the quality of individual research. The data was analyzed by gender and study design, therefore looking at separate and combined estimates for men and women and different types of studies, such as case control and cohort studies. Case control studies compare people with the disease with those ones that do not have the disease. Cohort studies follow a group of people for a certain period of time and either compare them within the same group or with another group that is representative of the general population.
The results of a cohort study showed that people who did the most exercise had a 24 per cent lower risk of developing colon cancer compared with those who exercised the least. For men, the number was 24 per cent as well, and for women it was 21 per cent. Findings from case-control studies were much stronger. The risk of colon cancer was 31 per cent lower for those adults who led the most active way of life, compared to 17 per cent lower disease risk for those who exercised the least.
Kathleen Wolin said, "These results give us a very reliable calculation of the positive effect that exercise can have on reducing colon cancer risk. It is very positive to see that exercise has such a clear benefit in reducing cancer risk and we hope it will encourage people to enjoy a healthy active lifestyle as well as treating it as a way to minimize their colon cancer risk."
However, there are a few limitations with meta analysis of observational data, which the researchers acknowledge. One such limitation is that different studies looked at physical activity in different ways, with some including a leisure activity such as jogging or swimming, and others concentrating on occupational activity such as walking or digging for both men and women. Combination of the results of these studies adds to 'heterogeneity' or variations in the design and methods of between studies.
While exercise has many benefits anyway, the researchers are planning to call for more research in order to establish the type, intensity and duration of exercise needed to reduce colon cancer risk. In addition, this further research could form the basis for more detailed public advice on how intensive and how long this physical activity needs to be.
Meanwhile, it is suggested that some exercise is better than no exercise, and it can prevent an expanding range of conditions. Even light exercise, such as walking, can be good heart health, so it can be beneficial to include it into daily routine when possible. "There is an ever-growing body of evidence that the behavior choices we make affect our cancer risk. Physical activity is at the top of the list of ways that you can reduce your risk of colon cancer," concluded Kathleen Wolin.
More than 100,000 Americans are diagnosed with colon cancer and about 40,000 with rectal cancer every year. Earlier studies have indicated that risk factors in developing the disease include having polyps, a family history of the condition, consumption of red meat in big quantities, low levels of selenium, having inflammatory bowel disease and smoking. The frequency of colon cancer varies around the world. Colorectal cancer is very common in the Western world and is rare in Asia and Africa. In countries where the people have adopted western diets, the incidence of the disease started to go up.
The study is published in the advanced online 10 February issue of the British Journal of Cancer.
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