Colorectal cancer refers to cancer that starts in the large intestine (colon) or in the rectum. It can also be called colon cancer and rectal cancer, but they are grouped together because they have many similar features.
Most colorectal cancers start from non-cancerous growths called polyps, which usually form on the inner wall of the colon or rectum. Polyps can be found and removed during a procedure called a colonoscopy. While there are several types of polyps, the most common are adenomatous polyps or adenomas, also called “pre-cancerous” polyps. They are especially important to remove to prevent them from developing into cancer.
How Common Is Colorectal Cancer?1
8% of new cancers
Colorectal cancer makes up 8% of all new cancers diagnosed each year. It is the third most common cancer in both men and women in the US.
1 in 24 women
Approximately 1 in 24 women will develop colorectal cancer in their lifetime.
1 in 23 men
Approximately 1 in 23 men will develop colorectal cancer in their lifetime.
How Genetic Mutations Increase Colorectal Cancer Risk
Women and colorectal cancer risk
Risk among US women to develop colorectal cancer.
Men and male colorectal cancer risk
Risk among US men to develop colorectal cancer.
People of certain ethnicities have a higher risk to develop colorectal cancer.
African Americans and people of Ashkenazi Jewish descent have higher risks of developing colorectal cancer than individuals of other ethnicities. Researchers are still investigating why this is the case.
Having a family history of colorectal cancer increases risk.
Especially if the colorectal cancer in the family was diagnosed at a young age (typically under the age of 50), or in a first-degree relative (parent, sibling or child). This could be due to shared environment, lifestyle, and/or genetic background.
Aspects of your own health history increase risk.
Certain type of polyps, especially adenomatous polyps, increase the risk of developing colorectal cancer.
Having a previous colorectal cancer increases the risks of a second colorectal cancer even after successful treatment. This is because colorectal cancer can develop in any remaining areas of the colon or rectum.
Certain conditions that cause inflammation of the lining of the colon over a long period of time increase the risks of colorectal cancer. These conditions are referred to as Inflammatory bowel disease (IBD) and include ulcerative colitis and Crohn’s disease.
People with type 2 diabetes (usually non-insulin dependent) may have an increased risk of colon cancer.
Alcohol and tobacco use can increase risk.
Both heavy alcohol use and long-term smoking have been linked to increasing the risk of colorectal cancer. The American Cancer Society recommends limiting alcohol use to no more than two drinks a day for men and one drink a day for women and not smoking.
There are factors that can decrease risk.
Many factors can decrease the risk of colorectal cancer, such as high activity levels, lower body mass index (BMI), and a healthy diet which is low in processed and red meat, and high in fruits, vegetables and whole grains.
- SEER Cancer Statistics Factsheets: Female Breast Cancer. Surveillance, Epidemiology, and End Results (SEER) Program, National Cancer Institute Website. Accessed April 7, 2015. Available at seer.cancer.gov.
- Colorectal cancer risk factors. American Cancer Society Website. Updated January 20, 2016. Available at www.cancer.org.