Highlights
- Colorectal cancer incidence rates have been increasing in younger adults (ages 30 to 49) since around 2005.
- Colorectal cancer incidence rates are decreasing in people age 50 and over.
- Colorectal cancer is largely preventable by modifying lifestyle risk factors and regular screening.
- Colorectal cancer is the third most common cancer diagnosed in men and women.
Overall incidence rates of new cases of colorectal cancer in Ontario have been declining since the mid-1980s, but the rates in younger adults (ages 30 to 49) increased by 5.2% per year between 2005 and 2012. Both colon and rectal cancer rates are contributing to these increases, which are similar among men and women. Colon cancer rates increased by 4.3% per year since 2005 and rectal cancer rates increased by 7.2% per year since 2006. Prior to 2005 colon cancer incidence rates were slightly decreasing at 0.9% per year and rectal cancer rates were increasing at only 0.7% per year before 2006. The pattern in the United States is similar, with published research reporting decreases in older age groups and increasing incidence in those under age 50.[1]
Colorectal cancer is considered largely preventable. It has been linked to well-established modifiable lifestyle risk factors, such as eating red meat or processed meat, excessive consumption of alcohol[2] and excess body weight. While the reasons for the recent rises in incidence among younger adults are mostly unknown, they may be partly explained by the increased prevalence of these modifiable risk factors in this age group. There is also sufficient evidence that supports cigarette smoking as a risk factor for colorectal cancer.[3] Physical activity and consumption of foods containing dietary fibre have been shown to have a protective effect.[2]
In addition to modifying lifestyle risk factors, colorectal cancer screening can help with prevention by identifying and removing pre-cancerous lesions. Screening is currently recommended for people aged 50 to 74 at average risk. Individuals with a family history of colorectal cancer have a higher risk of developing the disease at a younger age and may be advised to begin screening earlier. Despite rising incidence rates, screening is not recommended in Ontario for those under age 50 at average risk because it is still uncommon in younger adults, with 92.1% of cases between 2010 and 2012 (24,010 cases) occurring in people age 50 and over. Individuals can help reduce their risk by quitting smoking, limiting alcohol consumption, maintaining a healthy body weight, being physically active, eating a diet high in fibre (including vegetables, fruit and whole grains) and limiting intake of red and processed meat.
In 2012, colorectal cancer was the third most common cancer diagnosed in men and women in Ontario. Although the majority of newly diagnosed colorectal cancer cases occur in people over age 50, rising incidence among younger adults is of concern. The increasing prevalence of modifiable risk factors in this population has the potential to lead to further increases in colorectal cancer incidence in the future.
To find out more information on risk factors for colorectal cancer and to assess your risk, see MyCancerIQ.ca.