Adherence to lifestyle recommendations reduces risk of colorectal cancer by 23%

Research: Association of adherence to lifestyle recommendations and risk of colorectal cancer: A prospective Danish cohort study

Almost a quarter of colorectal (bowel) cancer cases could be prevented if people followed healthy lifestyle advice in five areas including diet and exercise, says a new study published on bmj.com today.

Researchers from Denmark found that following recommendations on physical activity, waist circumference, smoking, alcohol and diet could reduce the risk of developing bowel cancer considerably - by 23%.

Bowel cancer is the third most common cancer in the UK where more than 38,600 people are diagnosed with the condition every year. It is the second most common cause of cancer death in the UK, killing more than 16,250 people each year.

There is much evidence that implicates modifiable lifestyle factors such as smoking, physical activity, body composition, alcohol and diet.

The Danish researchers wanted to study the link between following healthy lifestyle advice and risk of bowel cancer in middle-aged people. They also wanted to find out the proportion of bowel cancer cases that might be linked to lack of adherence to the advice.

They studied data on 55,487 men and women aged 50-64 (bowel cancer is rare amongst people under 40) not previously diagnosed with cancer. The people were studied over almost 10 years up to 2006.

All participants filled in a lifestyle questionnaire including questions about social factors, health status, reproductive factors and lifestyle habits as well as a food frequency questionnaire developed to assess average intake over 12 months.

The researchers created a healthy lifestyle index using internationally accepted public health recommendations from the World Health Organization, World Cancer Research Fund and the Nordic Nutrition Recommendations.

These included being physically active for at least 30 minutes a day, having no more than seven drinks a week for women and 14 drinks a week for men, being non-smoker, having a waist circumference below 88 cm for women and 102 cm for men and consuming a healthy diet.

During the follow-up period, 678 people were diagnosed with bowel cancer.

After looking at how the participants managed to keep to each of the five lifestyle recommendations, the researchers calculated that if all participants (except the healthiest) had followed even one additional recommendation, it was possible that 13% of the bowel cancer cases could have been prevented.

If all participants had followed all five recommendations, then 23% of the bowel cancer cases could have been avoided.

The researchers conclude: "Our study reveals the useful public health message that even modest differences in lifestyle might have a substantial impact on colorectal cancer risk and emphasises the importance of continuing vigorous efforts to convince people to follow the lifestyle recommendations."

A second study also published today shows that adults with low education who used a decision aid when considering whether to have a bowel cancer screening test were more informed, but were less likely to have the test. Despite the lower uptake, the authors state that the decision aid improved informed choice in people with low education. They recommend that such aids should be made available for people who want to make an informed choice about screening and could be integrated within primary care.

However, an accompanying editorial says that before information interventions are adopted in practice, evidence is needed that they inform patients and meet the service need.