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Risk factors are things that raise your chances of getting a disease. For each person, there’s a mix of genetic, biological and lifestyle factors that play a part in colon cancer risk.
Aging, more than anything else, increases the risk of getting colon cancer. Researchers aren’t sure why. But clinician-researchers at Fred Hutch Cancer Center, like William M. Grady, MD, are working on the answer. The team in the Grady Lab is studying the microenvironment in the colon. Their goal is to better understand how age affects the chain of events that turns a normal cell into a cancer cell.
Although aging is a well-known risk factor, colon cancer has been on the rise in people under 50 for at least 20 years. Fred Hutch scientist Ulrike (Riki) Peters, PhD, MPH, co-led an international team of researchers to discover why. Some early-onset colon cancers happen in people with genes that increase their risk. The researchers found alcohol use and obesity are also drivers.
Another important risk factor for many people is their race or ethnicity. Anyone can get colon cancer. But risk is higher than average in some groups, like American Indian/Alaska Native (AI/AN) people and African Americans. To improve prevention for these groups, researchers are looking into the reasons for the difference in risk.
Schedule Your Screening
Talk to your primary care provider about colorectal cancer screening. UW Medicine Primary Care can help you get started with screening. You may be referred for a colonoscopy or a different screening test. Learn about Fred Hutch's relationship with UW Medicine.
If you need a colonoscopy, call 206.606.5342 to schedule your procedure at Fred Hutch Cancer Center – South Lake Union.
Genetic and Biological Risk Factors for Colon Cancer
Many of the risk factors for colon cancer are things you can't change. But it’s still important to be aware of them because they may affect your colon cancer screening plan, like when you should start having screenings.
- Age: Risk rises as you get older. It goes up significantly after age 50. But younger people can get colorectal cancer, too.
- History of cancer: If you’ve had colorectal cancer already or ovarian cancer, you are at higher risk.
- History of polyps: Most of these growths are benign, but some may turn into cancer. Almost all colon cancers start as precancerous polyps. Adenomatous polyps (adenomas) are most likely to become cancer.
- History of inflammatory bowel disease: This includes ulcerative colitis and Crohn’s colitis (or Crohn’s disease).
- Race and ethnicity: AI/AN people and African Americans are at greater risk of getting colorectal cancer than any other racial or ethnic group in the United States. They are also at greater risk of dying from the disease. Ashkenazi Jews may have inherited changes in their DNA that increase their risk.
- Family history of colorectal cancer or adenomatous polyps:
You are at higher risk if:- Your parent, sibling or child had colorectal cancer, especially if it was before age 50.
- Two or more relatives had colon cancer.
- Members of your family had adenomatous polyps.
- Familial adenomatous polyposis (FAP): This is a rare condition passed down in families. It causes hundreds of colorectal polyps. FAP can appear as early as the teen years and is very likely to lead to cancer.
- Lynch syndrome (hereditary nonpolyposis colon cancer, or HNPCC): Like FAP, this condition is also passed down in families. People with Lynch syndrome tend to get cancer at a young age without first having many polyps.
Lifestyle Risk Factors for Colon Cancer
There are some factors you can control that raise or lower your risk for colon cancer.
- Smoking: People who have smoked are more likely than nonsmokers to get colorectal cancer and to die from the disease.
- Diet: Diets high in red meats and processed meats increase risk. Diets high in vegetables and fruits decrease risk.
- Exercise: People who aren’t active are at higher risk. Those who exercise regularly are at lower risk.
- Weight: Being overweight or obese increases risk.
- Alcohol: Having three or more alcoholic drinks each day has been linked to colorectal cancer.
- Type 2 diabetes: People with type 2 diabetes are more likely to get colorectal cancer and may do worse after diagnosis.
Ways to Prevent Colon Cancer
There are two main ways to prevent colon cancer. One is to avoid factors that raise your risk. The other is to increase factors that lower your risk. These are sometimes called protective factors. Healthy lifestyle choices, like quitting smoking and eating a more plant-based diet, may help drive your risk down.
The most important choice you can make is to get a colon cancer screening. With a colonoscopy, physicians can find and remove polyps that could turn into cancer — stopping the disease before it starts.
“We are lucky to have screening tests for colorectal cancer. Many cancers do not,” said Stacey Cohen, MD, a medical oncologist at Fred Hutch who specializes in high-risk gastrointestinal cancers. Fred Hutch is working to halt colon cancer with efforts like our Population Health Colorectal Cancer Screening Program. Learn more about colon cancer screening, and talk with your primary care provider about getting screened yourself.
These diet and exercise choices may help lower your risk of colon cancer:
- Eat more vegetables, fruit and whole grains.
- Limit red meat and processed meats, like bacon or sausage.
- If you don’t drink alcohol, keep it that way. If you do drink, stick to no more than one drink per day for women or two drinks per day for men.
- Be as active as you can. Getting more exercise is thought to help protect you. You can add movement to your day in simple ways, like taking walks with family and friends or using the stairs instead of the elevator.
Colon cancer risk may be lower in some people who regularly take nonsteroidal anti-inflammatories (NSAIDs). But the effect may not hold true for everyone. For example, a study by Fred Hutch researchers found the benefit was lower in smokers and in people who were obese. In other words, different factors may interact with each other. NSAIDs can have side effects, like bleeding in the digestive system. So, experts don’t recommend starting regular NSAID use to prevent cancer.
Combination hormone replacement therapy (HRT) lowers the risk for invasive colorectal cancer in women after menopause, according to the National Cancer Institute. Combination HRT has both estrogen and progestin. (HRT with only estrogen does not affect risk.) Research by Fred Hutch scientists suggests HRT may do more to reduce colon cancer risk in women who are at higher risk due to genetic factors. At the same time, HRT may raise women’s risk for other health problems, like blood clots. If you are using or thinking of using HRT, talk with your health care team. Find out about all the risks and benefits before deciding what’s right for you.
Research has shown there may be a link between colon cancer and low vitamin D or low calcium. So far, there’s no definite answer on whether supplements reduce risk.
Genetic testing may show if you have certain gene changes (mutations) that can be passed down in families that increase the risk of colon cancer. There are tests to look for inherited syndromes, like familial adenomatous polyposis, Lynch syndrome and other conditions linked to colon cancer risk. Tests usually involve taking a small sample of blood.
If you have a family history of colorectal cancer, ask your health care team if it’s a good idea to get tested. Your team will take into account your personal health history and your family health history before making a recommendation. If tests are recommended, you may want to speak with a genetic counselor first. They can help explain what the tests do or don’t show and what the results might mean for you.
The Clinical Genetics and Genetic Counseling Service at Fred Hutch assesses cancer risk for people who are at high risk because of their personal or family history. For people with higher risk of gastrointestinal cancers due to genetic changes or family history, the Gastrointestinal Cancer Prevention Program can help. This program offers a personalized approach to risk assessment, screening and prevention.
It’s not yet clear if calcium helps protect against colon cancer, according to the National Cancer Institute. Some studies suggest risk may be higher in people who don’t get enough calcium through their diet. Researchers don’t yet know if taking calcium supplements lowers the risk.