The study, published online October 26 in BMJ, is one of the first to study the impact of multiple healthy behaviors, rather than just 1 factor. The impact of 5 factors — physical activity, waist circumference, smoking, alcohol intake, and diet — was assessed.
Even modest differences in lifestyle might have a substantial impact on colorectal cancer risk.
“Our study reveals . . . that even modest differences in lifestyle might have a substantial impact on colorectal cancer risk, and emphasizes the importance of continuing vigorous efforts to convince people to follow the lifestyle recommendations,” the authors conclude. The team is from the Institute of Cancer Epidemiology at the Danish Cancer Society in Copenhagen, Denmark.
Data From Lifestyle Questionnaires
The information comes from the Diet, Cancer and Health Cohort Study, which collected data on lifestyle from questionnaires completed by 57,053 people. All were born in Denmark, were 50 to 64 years of age, and did not have cancer when they filled out the questionnaire. People with a family history of cancer were excluded, as were those taking nonsteroidal anti-inflammatory drugs and women on hormone-replacement therapy, leaving 55,487 participants.
The researchers created a healthy lifestyle index using internationally accepted public health recommendations from the World Health Organization, the World Cancer Research Fund, and the Nordic Nutrition Recommendations.
The answers provided by the participants show that most of them followed 4 of the 5 factors contributing to a health lifestyle:
- 82% followed recommendations for exercise (being physically active for at least 30 minutes a day)
- 76% had a waist circumference within the recommended range (below 88 cm for women and 102 cm for men)
- 64% were nonsmokers (56% had never smoked)
- 59% had alcohol intake within the recommended limits (fewer than 7 drinks a week for women, and fewer than 14 drinks a week for men).
However, only 2% of participants followed all of the dietary recommendations, which included eating at least 600 g of fruit and vegetables daily, eating 500 mg or less of red and processed meat a week, eating at least 3 g of dietary fiber per megajoule of dietary energy, and getting 30% or less of total energy from fat.
During a median follow-up of 9.9 years, colorectal cancer was diagnosed in 678 individuals.
The risk for colorectal cancer was “significantly linearly related” to the lifestyle index, the researchers reported. The more recommendations that were followed, the lower the risk for colorectal cancer.
However, this association between lifestyle index and colorectal cancer was stronger in men than women. “The nonsignificant sex difference we found could be due to some biological differences or to a difference in the level or quality of reporting lifestyle,” the researchers explain. Women tended to overestimate the consumption of “desirable” items more than men, but there were fewer cases of colorectal cancer among women, so that analysis might have lacked statistical power, they add.
“If all participants had followed merely 1 additional recommendation, we estimate that 13% of the cases of colorectal cancer might have been prevented,” they researchers write.
“Furthermore, we estimate that 23% of the colorectal cancers in this cohort were associated with a lack of adherence to the recommendations for the lifestyle factors included in our study,” they conclude.