A new study shows that if you adopt a healthier lifestyle after bowel screening, it can lower your risk of both bowel cancer and other chronic diseases.

Previous studies have estimated that approximately half of all the cases of bowel cancer could have been avoided by not smoking, maintaining a normal body weight, healthy eating, doing physical exercise and drinking little or no alcohol. However, these studies have looked at what sort of lifestyle people have had generally throughout their lifetime.

"Previous studies have indicated that bowel screening might be a window of opportunity to be used as a teachable moment for lifestyle intervention to try help people change their lifestyle. However, we lack knowledge about whether the risk of getting bowel cancer is reduced by a change of lifestyle at this particular point in time. Together with researchers from the Song Lab at Harvard T.H. Chan School of Public Health, we therefore wanted to find out what happened if you changed your lifestyle in a positive or negative way after bowel cancer screening. We also studied the risk of developing other major chronic diseases", says Markus Dines Knudsen. He's a postdoctoral fellow at the Department of Nutrition, Institute of Basic Medical Sciences, at the University of Oslo.

Changes in lifestyle reduced the risk of bowel cancer by 14 per cent

In a new study published in the American Journal of Gastroenterology, the researchers used data from three big American studies, that only included participants who had been screened by colonoscopy.

The participants were first asked about their lifestyle and diet before they were screened. Then they were asked the same questions on repeated occasions during the years that followed. The researchers calculated a lifestyle score of between 1 to 5, based on how the participants were doing in regard to the risk factors smoking, body mass index, physical activity, alcohol and diet.

The questions about diet concerned for example how much red meat, processed meat, fibre, whole grain foods, dairy products and calcium they ate.

The researchers followed the participants for up to 30 years after their screening and recorded any diagnoses of bowel cancer or other major chronic diseases.

"It turned out that making healthy choices helps. The study showed that for every point of lifestyle improvement during the years following the screening, there was a 14 per cent lower risk of bowel cancer and an 11 per cent lower risk of developing other chronic diseases", explains Knudsen.

One lifestyle improvement point is equivalent to for example becoming more physically active, losing weight or drinking less alcohol.

Unhealthy choices increased the risk of bowel cancer by 70 per cent

Some of the participants did not change their lifestyle for the better and some lived less healthy than before. Those whose lifestyle score worsened by two points or more ended up with a 70 per cent higher risk of bowel cancer and a 21 per cent higher risk of developing chronic diseases, compared to those whose lifestyle score remained the same as before their screening.

"These are interesting results since we are dealing with a group who actually had a reduced risk of bowel cancer because they were screened for bowel cancer and pre-cancerous conditions. In spite of this, we found that when their lifestyle worsened, they had a pronounced increase in risk of getting bowel cancer", says Knudsen.

New study to be launched with the Norwegian Cancer Registry

Knudsen and his Norwegian colleagues are now focusing on the Norwegian bowel screening programme and want to find out whether this could be a gateway to promoting a healthy lifestyle.

"We are now launching a study in Norway, in collaboration with the Norwegian Cancer Registry’s Bowel Screening Programme. We will be testing different degrees of follow-up and support on cancer-preventive lifestyle habits over a two-year period. In the longer term, we will also look at how these measures affect the incidence of cancer and mortality", he adds.

More information:
Lifestyle change after initial colonoscopy screening and incidence of colorectal cancer and major chronic diseases