In a recent study, researchers from China, Korea, and the US explored the relationship between a sedentary lifestyle and the risk of young-onset colorectal cancer.
Colorectal cancer is a form of cancer that starts in the colon or rectum and is typically diagnosed in later life. However, young-onset colorectal cancer, diagnosed before 50 years of age, is becoming increasingly common worldwide. The disease can appear differently than the late-onset form and is often found at a more aggressive stage than colorectal cancer in older patients, increasing the years of life lost in young patients. Until recently, the cause of this alarming trend had not been explained.
In a new JNCI Cancer Spectrum study, researchers from the US, Korea, and China examined the relationship between rising levels of young-onset colorectal cancer and sedentary lifestyles.
Sedentary lifestyles have become the fourth-leading mortality risk factor
Physical inactivity is an important public health concern for people of all ages. Sedentary lifestyles have become the fourth leading mortality risk factor worldwide, and are linked to a number of chronic diseases including cardiovascular disease, cancer, and diabetes. In 2013, more than three-quarters of Canadian adults and over 90% of children and youth in Canada did not meet the guidelines for physical activity. These guidelines suggest a minimum of 60 minutes of moderate-to-vigorous physical activity each day for children and youth and 150 minutes of exercise each week for adults.
Increasing sedentary behaviours can be partly attributed to higher rates of office-bound work and passive consumption of media, such as television. People who meet the minimum recommended amounts of exercise are still at risk of poor health if a significant amount of their waking hours are spent being physically inactive.
In the study, researchers looked at sedentary behaviours including TV viewing time in 89,278 women aged 25 to 42. Study participants were followed over 22 years and monitored for young-onset colorectal cancer. In total, researchers reported 118 cases of young-onset colorectal cancer in these patients.
Watching more than two hours of TV per day associated with an increased risk of colorectal cancer
They found that women who watched more than one hour of TV per day had a 12% higher risk of developing the disease and that those who watched more than two hours per day had a nearly 70% increased risk. This association was even more pronounced for rectal cancer than with colon cancer. Women who reported more screen time also had a higher rate of diabetes, used fewer multivitamins, were less physically active, and had poorer quality diets than those with less screen time.
The results were consistent across patients independent of body mass index (BMI) and other typical risk factors of colorectal cancer. However, patients with a higher BMI, those who smoked, and less physically active patients were at a greater risk of young-onset colorectal cancer.
Active lifestyles are necessary to prevent chronic disease
The findings demonstrate the importance of maintaining an active lifestyle to prevent chronic disease. Reducing periods of inactivity can help lower the risk of young-onset colorectal cancer and improve overall health. The study also helps to identify those at high risk of colorectal cancer who might benefit from earlier screening and intervention.
Further studies are needed to determine how a sedentary lifestyle causes these biological changes in the body and what preventative measures can be used to help young at-risk patients.
Written by Braydon Black, BSc
- American Cancer Society. What is colorectal cancer? Atlanta, GA: ACS; [updated 2018 Feb 21; cited 2019 Feb 17]. Available from: https://www.cancer.org/cancer/colon-rectal-cancer/about/what-is-colorectal-cancer.html
- Nguyen LH, Liu P, Zheng X, Keum N, Zong X, Li X. Sedentary behaviours, TV viewing time, and risk of young-onset colorectal cancer. JNCI Cancer Spectrum [Internet]. 2019 Jan; [cited 2019 Feb 17];2(4). Available from: https://academic.oup.com/jncics/article/2/4/pky073/5301781 doi: 10.1093/jncics/pky073
- Government of Canada. How healthy are Canadians? Physical inactivity [Internet]. Ottawa, ON: Government of Canada; [updated 2017 Apr 11; cited 2019 Feb 17]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/how-healthy-canadians.html#s3-1-2
- Public Health Agency of Canada. Health status of Canadians 2016: report of the Chief Public Health Officer. Ottawa, ON: Public Health Agency of Canada; 2016. 64 p. Cat. No.: 978-0-660-05480-3.