Reduce your risk of colon and rectal cancer with these basic steps

Diet is one risk factor for colorectal cancer that can be controlled, specifically the amount of red meat and processed meat you eat. (miodrag ignjatovic/E+/Getty Images via CNN Newsource)

Colorectal cancer stands as the third leading cause of cancer-related deaths in U.S. men and the fourth leading cause in U.S. women, according to the American Cancer Society.

This year, over 150,000 Americans will be diagnosed with this cancer, and 52,900 will die from it, according to the organization’s estimates. The lifetime risk of developing colorectal cancer is estimated to be about one in 24 for men and one in 26 for women.

Editor’s note: Colorectal cancer was the fourth most commonly diagnosed cancer in Canada in 2024, with an average of 69 Canadians diagnosed every day. Read more about it through Colorectal Cancer Canada.

Because March is Colorectal Cancer Awareness month, I wanted to speak to an expert about the risk factors for this type of cancer. How is it treated? When should people begin colorectal cancer screenings, and what types of tests are available? Who should start screening earlier? And what can people do to try to lower their risk of developing colorectal cancer?

To help us with these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore’s health commissioner.

CNN: What is colorectal cancer?

Dr. Leana Wen: Colorectal cancer refers to colon cancer, which starts in the colon, and rectal cancer, which starts in the rectum. Sometimes, people refer to “colon cancer” and “colorectal cancer” interchangeably, but technically colon cancer is part of the broader category of colorectal cancer.

CNN: What are the risk factors for colorectal cancer?

Wen: Risk factors for colorectal cancer are divided into ones associated with lifestyle, which therefore can be changed, and those that are not.

In terms of lifestyle risk factors, a major one is being overweight or obese. Another is having diabetes. Others include smoking, alcohol use and diets with a lot of red meats and processed meats.

In terms of risk factors not associated with lifestyle, inherited syndromes, such as Lynch syndrome and familial adenomatous polyposis, substantially increase colorectal cancer risk. People with inflammatory bowel disease, such as Crohn’s disease and ulcerative colitis, also are at elevated risk, as are those who have had radiation to the abdomen or pelvic area and individuals with a family history in a first-degree relative of colorectal cancer.

Your age is also important. Colorectal cancer is far more common after age 50, though in recent years, there has been a rise in this cancer among younger people. In fact, the rate of colorectal cancer in people under 50 is expected to double by 2030, according to some estimates, and colorectal cancer is on track to being the leading cause of death for people ages 20 to 49.

CNN: Why has there been a rise in colorectal cancer in younger people?

Wen: We don’t know the exact cause, and it probably involves several factors. Since obesity is a risk factor, increasing rates of obesity may account for some of the rise in colorectal cancer. Changes in dietary habits and increasingly sedentary lifestyles also may be associated with higher cancer risk. Environmental factors could play a role, too, for instance, cancer-causing chemicals in soil, water and food.

CNN: How is colorectal cancer treated?

Wen: Treatment depends on multiple factors, including the stage of cancer and the person’s overall health. Surgery is the most common treatment. Radiation and chemotherapy are sometimes offered, too, and there are also targeted therapies, including immunotherapies that help a person’s immune system fight cancer.

As with other types of cancers, the prognosis is best if the cancer is localized and has not spread at the time it is diagnosed. That’s why screening is so important: to try to catch the cancer early.

CNN: When should people begin colorectal cancer screenings, and what types of tests are available?

Wen: The U.S. Preventive Services Task Force has recommended since 2021 that most adults 45 to 75 years old be screened for colorectal cancer. This represents a change from prior guidelines, which advised that screening begin at age 50. Between ages 76 and 85, the task force states that the screening decision should be an individual one made in consultation with one’s physician. The task force recommends discontinuing screening after age 85.

Several types of approved methods exist for colorectal cancer screening. The first method is visual inspection of the colon. The gold standard of these tests is the colonoscopy. This procedure involves a gastroenterologist passing a long tube through the patient’s bowels, and it generally requires that the person is put under anesthesia during the procedure. A related procedure, called the sigmoidoscopy, is quicker and requires less sedation, but it results in a more limited view of the bowels. People can also receive a CT colonography, also called a virtual colonoscopy, to view the bowels through a scan.

The colonoscopy is generally recommended every 10 years. The sigmoidoscopy or CT colonography would be recommended every five years. The benefit of the colonoscopy and sigmoidoscopy over the CT colonography is that if a precancerous polyp is seen, it could be removed during the procedure to prevent it from developing into cancer in the future.

A second type of test is stool-based tests. Patients collect a stool sample at home and then send it to a lab to be analyzed. The test looks for certain things in the stool, such as blood or tumor DNA, that could suggest cancer. These tests need to be done every one to three years. If there is a concerning finding, the patient is generally recommended for a colonoscopy or sigmoidoscopy for further testing.

The U.S. Food and Drug Administration approved another type of test in 2024. This blood test has an accuracy rate comparable to that of stool tests. I think it’s a good option for individuals who may otherwise not get colon cancer screenings. Indeed, according to the American Cancer Society, as many as one in three people who should get tested for colon cancer have never received any screening tests.

CNN: Who should start screening earlier?

Wen: It’s important to note that the age of 45 to start screening is for adults at average risk of colon cancer.

People who should begin screening at earlier ages are those at higher risk for developing colorectal cancer. Those people with genetic syndromes, for instance, inflammatory bowel disease, or personal or family history of colorectal cancer or colorectal polyps may need to begin earlier and receive screening more frequently. People who have such personal or family history should discuss options with their provider.

CNN: What can people do to try to lower their risk of developing colorectal cancer?

Wen: Everyone should regularly visit their primary care provider, at least once a year. This is the time to discuss screening recommendations that consider their personal and family cancer history.

It’s also the opportunity to discuss lifestyle-related risk factors that could be changed. Stopping smoking and reducing alcohol consumption can substantially reduce risk, as can receiving counsel on weight loss to treat obesity. Increasing physical activity and modifying diet to one with less red and processed meat and with more fruits, vegetables, whole grains and fiber can help as well.

Katia Hetter, CNN