Is Colon Cancer Hereditary? Know Your Risk and What to Do About It

Colon and rectal cancers, collectively referred to as colorectal cancer, are the third most common types of cancer in the U.S. excluding skin cancer, according to the American Cancer Society. Although lifestyle and other environmental factors can play a role in colorectal cancer risk, a small percentage of people who get the disease are genetically predisposed. Knowing your family history and understanding genetics can help you learn whether you fall into that group.

Hereditary Conditions and Colon Cancer

All forms of cancer are caused by genetic mutations that lead to abnormal cell growth. These mutations can be inherited from a family member, caused by your environment or other factors, or caused by a combination of the two.

“It’s important to understand the difference between hereditary cancers and family history, especially when it comes to colorectal cancer,” says Ronda O’Connell, ANP-BC, of Beaufort Memorial Primary Care. “Hereditary cancers can develop if you inherit a gene mutation or a condition that causes colorectal cancer. You might have a family history because of that inherited condition or mutation. However, family members may also share habits, such as eating a lot of red meat or smoking, that can also increase the risk of colorectal cancer, so you can still have a family history of the disease without having an inherited genetic condition or mutation.”

The two most common inherited conditions that increase colorectal cancer risk are:

• Lynch syndrome: This condition is responsible for between 2% and 4% of all colorectal cancers. People with Lynch syndrome have up to a 50% lifetime risk of developing colorectal cancer. This syndrome may increase the risk of developing other types of cancer too.
• Familial adenomatous polyposis (FAP): FAP accounts for approximately 1% of all colorectal cancers. There are multiple types: In the most common, polyps start developing in the colon and rectum when a person is around 10 to 12 years old. Nearly all people with FAP will develop colorectal cancer by age 40. FAP may also raise the risk of developing other cancers.

Nonhereditary Risk Factors for Colon Cancer

Most people who develop colon cancer do not have a family history of colorectal cancer. In fact, only about 30% of people who develop colorectal cancer have a family member who has also had the disease. Your risk increases if that family member is a first-degree relative, such as a parent, child or sibling.

Outside of inherited genetic conditions, many environmental and genetic factors can place you at high risk for colon cancer.

Risk factors that are out of your control include:

• A history of ovarian or colorectal cancer
• Being 50 years old or older
• Being Black or of Ashkenazi Jewish descent
• Having an inflammatory bowel disease (Crohn’s disease or ulcerative colitis)
• Having Type 2 diabetes

Risk factors you may be able to control include:

• Alcohol consumption — drinking three or more alcoholic drinks daily for men or two or more a day for women
• Eating a lot of red meat or processed meats
• Obesity
• Not getting enough exercise
• Smoking

Read More: Colon Cancer Symptoms: How to Recognize a Potential Problem

Genetic Testing for Colon Cancer

Talk with your provider about your risks as early as possible if you have a family history of colorectal cancer. Depending on whether your risk is higher due to an inherited condition or external factors, your provider can help you determine whether you need genetic testing. Genetic tests look for inherited gene mutations and may give you more information about your risk of developing colorectal cancer. Based on the results, your provider can recommend earlier or more frequent screenings or other preventive steps that can lower your risk.

Read More: A Growing Risk for Young Adults

Screening for Colon Cancer

People at average risk of colorectal cancer need a colonoscopy only once every 10 years beginning at age 45, but if you have hereditary or genetic risk factors, you may need them earlier or more often. Screenings for people with a family history of colorectal cancer typically start at age 40.

“Regardless of your genetic makeup, a colonoscopy is the most effective way to screen for colon cancer,” O’Connell says. “These screenings allow us to find and remove colon cancer early, before it has spread.”

An at-home colorectal cancer screening may be an option if you are not at high risk for colorectal cancer. At-home screenings should be done every three years. If you have a positive at-home screening, you will need a colonoscopy.

Colorectal cancer is highly treatable when found before it spreads, even if it’s hereditary. Early detection of colorectal cancer typically leads to better outcomes and an increased survival rate. No matter which screening methods you choose, the most effective way to help prevent and effectively treat colorectal cancer is to detect it early.

Talk with your primary care provider to discuss your risks and schedule a screening. Need a provider? Find one accepting new patients.