Family History of Colon Cancer: Who Needs to Start Colonoscopies Sooner?

The standard age to get your first colonoscopy is 45. However, if you have a family history of colorectal cancer or high-risk polyps, you may need to start getting screened at an earlier age. This is because certain genetic or inherited conditions can increase the risk of colorectal cancer, as well as breast and ovarian cancers.

"The more detail we have about your family history, the better decisions we can make together about how to reduce your risk for colorectal cancer,” says Dr. Rachel Schiesser. “We may be also able to catch the disease early, when it is easiest to treat.”

By understanding where and how these conditions appear in your family tree, your doctor can customize a screening plan to help protect your future health. This may also help prevent colorectal cancer in other family members as well.

How does family history affect cancer risk?

Colorectal cancer is a multifactorial disease. That means there are many details that can raise or lower your personal risk of developing the disease, including your lifestyle, environment and family health history.

Using this information, your doctor can recommend the best cancer screening schedule for you. Talk with the doctor about your family’s history of colorectal conditions, such as:

• Colon cancer

• Rectal cancer

• Advanced or high-risk polyps, which are precancerous growths in the colon

• Certain genetic conditions associated with cancer, such as Lynch syndrome or familial adenomatous polyposis (FAP)

In general, your doctor will want to know about first- or second-degree relatives who had any of these conditions. This includes your parents, siblings, children, grandparents, grandchildren, aunts and uncles, and nieces and nephews.

While having a family history of colorectal cancer can increase your risk, it doesn’t mean you will develop cancer. However, knowing who in your family had cancer and their age at diagnosis can help guide your screening plan.

“If a family member was diagnosed with colorectal cancer early in life, you may need to start colonoscopies at 10 years earlier than their age at diagnosis,” Dr. Schiesser says. “For example, if your mother was diagnosed at age 45, the doctor may recommend you begin screening at age 35.”

If you have a significant family history of colorectal cancer, talk with your doctor about whether genetic testing might be right for you.

What if I don't know my family history?

If you were adopted or are unable to access your family medical history, your care team will generally assume you’re at an average risk of colorectal cancer.

"If you don't know your family history, you’ll need to be more vigilant about your body,” Dr. Schiesser says. “See your primary care doctor for regular checkups and pay attention to concerning symptoms.”

Early signs of colorectal cancer can be vague and easy to mistake for acute digestive illness. If you notice any of these potential signs of colorectal cancer, talk with a doctor right away:

• Changes in bowel habits (frequency of bowel movements or consistency of stool)

• Rectal bleeding (blood in the stool)

• Abdominal or pelvic pain

• Unexplained weight loss

What type of colorectal cancer screening is best?

Colonoscopy is the gold standard for colorectal cancer screening. It allows your doctor not only to see polyps but also remove them right away. Getting a colonoscopy is generally quick and painless, and most people are back to their normal activities the next day.

"The prep is usually the worst part for most people, and it’s improving all the time,” Dr. Schiesser says. “We now have lower-volume prep drinks, and there is a pill prep option.”

There are other ways to screen for colon cancer, such as stool sample testing or CT colonography — a 3D X-ray of the colon. However, these options are only indicated for average-risk individuals because they are less preventive.

"Non-invasive tests don't tell you a lot about whether you have precancerous polyps," Dr. Schiesser says. “Most people tolerate colonoscopy very well, especially people who are younger adults and relatively healthy.”

(Related: How to Prepare for a Colonoscopy)

Tips to gather your family history

Before you talk with your doctor about your family history, gather details from your relatives. This could mean some phone conversations with older relatives or taking time to document the family health conditions you’re aware of, including:

• Which family members were diagnosed with colon polyps or colorectal cancer

• Your relation to them

• Their age at diagnosis

• Any known genetic mutations or related conditions

Bring notes about your family history to your doctor visit. These details, along with a discussion about your lifestyle and overall health, help inform your colorectal cancer screening recommendations.

Prevention is the best approach, and early detection of colorectal cancer significantly increases your chances of successful treatment. Understanding your family history and following your screening plan is a smart combination for a longer, healthier life.