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Risk Factors for Colorectal Cancer
A risk factor is something that increases your likelihood of getting a disease or condition.
It is possible to develop colorectal cancer with or without the risk factors listed below. However, the more risk factors you have, the greater your chance of developing colorectal cancer. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.
Generally, colorectal cancer is found more often in men than in women. Specifically, women have higher rates of colon cancer, while men have higher rates of rectal cancer. Colorectal cancer can develop at any age, but is more likely found in those aged 65 years and older. Risk typically increases starting at age 50.
Other factors that may increase your chance of colorectal cancer include:
Heredity is perhaps the strongest risk factor for developing colorectal cancer. It is estimated that approximately 20% of all cases of colorectal cancer are hereditary. This risk increases if you have a primary relative, such as a parent, sibling, or child who develops colorectal cancer.
Hereditary colon cancer occurs at a younger age. As a result, anyone with a history of colon cancer in a relative should seek screening early. Guidelines recommend a screening at age 40 or 10 years younger than the earliest age at which a relative developed colon cancer, whichever is younger. With inherited forms of colon cancer, the presence of the disease before age 60 in near relatives increases one’s own risk.
The 2 most common forms of inherited colon cancer are:
- Lynch syndrome—This is a fast-growing form of colorectal cancer. It accounts for about 5% of all colorectal cancer cases. Typically, people with this form develop cancer in their 40s.
- Familial adenomatous polyposis (FAP)—People with this type of colorectal cancer develop hundreds of polyps at a very young age, sometimes as early as their teens. Initially, polyps are benign but do become cancerous over time. This type of colorectal cancer is rare. It only occurs in 1% of all colon cancer cases. The likelihood of colon cancer is almost 100% by age 40. Many opt to have most or all of their colon removed as a preventive measure.
Colorectal cancer has been strongly associated with lifestyle factors. The following factors may increase your risk of developing colorectal cancer:
- Diet—Diets high in fat, particularly fat from animal sources, and low in fiber are associated with an increased risk of colorectal cancer. Eating a diet that is high in fruits and vegetables may help lower the risk.
- Lack of exercise—A sedentary lifestyle increases the risk of colorectal cancer. Even moderate exercise of 30 minutes per day is beneficial.
- Smoking —Smokers are at increased risk of getting colorectal and other cancers. The risk of dying from colorectal cancer is also higher for smokers than nonsmokers.
- Alcohol —Three or more alcoholic beverages a day increases risk of colorectal cancer.
The following medical conditions have been shown to increase the risk of developing colorectal cancer:
- Ulcerative colitis and Crohn disease—Infection and irritation cause cell changes in the wall of the colon and rectum.
- Colon polyps—Abnormal growths can sometimes turn into cancer if left untreated.
- Previous colorectal cancer—Cancer can recur in new areas of the colon and rectum even if a tumor was surgically removed. The earlier in age you had colorectal cancer, the more likely it is to come back.
- Type 2 diabetes —People with type 2 diabetes have a higher risk of colorectal cancer. Diabetes is also be associated with negative outcomes during and after treatment.
- Obesity —Obesity increases the risk of colorectal cancer, particularly when weight is distributed in the waist, rather than on the hips and thighs.
Race and Ethnicity
African-Americans carry the highest risk of developing and dying from colorectal cancer.
Ashkenazi Jews are at an increased risk because of a specific genetic mutation.
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Colorectal cancer. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003096-pdf.pdf. Accessed February 27, 2020.
Colorectal cancer. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/colorectal-cancer. Updated January 22, 2020. Accessed February 27, 2020.
Glynne-Jones R, Wyrwicz L, Tiret E, et al. Rectal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2017 Jul 1;28.
- Reviewer: Mohei Abouzied, MD
- Review Date: 12/2019
- Update Date: 02/27/2020