How are polyps linked to colorectal cancer?

About half of adults over age 50 will develop colon polyps, or noncancerous growths in the lining of the colon or rectum. Around 10 percent of these polyps will go on to become cancerous—affecting about 1 in 25 people in the United States, according to the American Cancer Society. But research has shown that your odds may be lowered if you exercise regularly.

Any activity will help. Take a brisk stroll, pull weeds, or chase the kids around in the yard. Your age doesn’t matter; research suggests that being active can reduce your risk of colorectal cancer (cancer that develops in the colon or rectum) no matter how young or old you are.

Polyps and their connection to colorectal cancer

Polyps form from irregular cells. They typically aren't dangerous, and become more common with age. When polyps do develop into cancer, they’re usually slow to progress. Once a pre-cancerous polyp has grown big enough to be seen during an examination, they generally take about 10 to 15 years to become cancerous.

If a person is regularly screened, most polyps can be identified and surgically removed. Most people should begin screening at age 45. Certain groups are more at risk, including older people and African Americans. If you have a family history of colorectal cancer, you are also at higher risk.

Protection from polyps

While you can’t alter your age, your race, or your family history, you may be able to reduce some of your risk for colorectal cancer by making lifestyle changes. These changes include eating a healthy diet, avoiding alcohol, quitting smoking, maintaining a healthy weight—and being physically active.

Getting regular moderate-to-vigorous activity can lower your risk of colorectal cancer, according to the American Cancer Society. And the more, the better; people who exercise for more time each week, and/or more vigorously, may reduce their risk even further.

A 2022 review published in the journal Cancer Cell International supports this. For the review, scientists looked at the available research linking exercise with colorectal cancer prevention. They found that a large number of clinical trials have now shown that regular physical activity can lower colorectal cancer risk.

More specifically, they found that getting consistent exercise can lower the risk of cancer by 23 to 24 percent. Regular vigorous exercise may lower it even more, by 26 percent. And by contrast, being sedentary, or spending most of the time sitting, can raise the risk of colorectal cancer by 30 percent, though this may also be combined with other risk factors like an unhealthy diet and inflammation.

Exercise has many benefits. In addition to helping prevent colorectal cancer, exercise can improve your health in almost every other way, including serving as protection against many other types of cancers. And the research suggests that if you do develop colorectal cancer and need treatment, regular exercise can help you significantly raise your quality of life, both during and after the cancer treatment. It may help prevent the cancer from recurring, too.

More exercise is better

To boost your overall health and fitness, government experts advise getting 150 minutes of moderate-intensity exercise each week, or 75 minutes of weekly vigorous activity. They also advise doing muscle-strengthening exercises twice a week, making sure to work on each of your muscle groups, like your arms, legs, back, abdomen, and chest.

Going beyond these recommendations can bring even more health benefits. But if you're short on time, it's important to know that even a little exercise is worthwhile and will bring real health benefits.

Why exercise helps

The Cancer Cell International review authors also looked at why exercise seems to be so beneficial. They found evidence that exercise may help to lower inflammation, which has been linked to cancer. Physical activity may also affect insulin as well as leptin and ghrelin, two weight-related hormones, in a way that helps inhibit colorectal cancer growth. Plus, exercise boosts immune-system function, which may help the body counteract early cancerous cells.

A healthy lifestyle for colorectal cancer prevention

Here are a few more ways to reduce your colorectal cancer risk:

Eat a healthy diet

Choose lots of veggies, fruits, and whole grains, and steer clear of processed meats like hot dogs or lunch meats. Try to lower your consumption of ultra-processed foods and red meat (like lamb, beef, or pork).

Don't smoke

People who smoke for a long time are more likely to get colorectal cancer and more likely to die from it, compared to people who don’t smoke. If you need help quitting, ask your healthcare professional (HCP) for resources.

Maintain a healthy weight

Being overweight or obese can raise your chances of developing colorectal cancer. It also raises your chances of dying from it. Choosing healthier foods and getting regular exercise will help you reach and maintain a healthy weight.

Avoid alcohol

Alcohol has been found to raise the risk of colorectal cancers. It’s best not to drink any alcohol. If you do choose to drink alcohol, men should have no more than two drinks per day and women should have no more than one. As a reminder, one drink means 5 ounces of wine, 12 ounces of beer, or 1.5 ounces of hard liquor.

Get screened for colorectal cancer

One of the best ways to help reduce your risk of developing colorectal cancer is being screened for the disease. The American Cancer Society recommends that adults with average risk factors start screenings at age 45.

There are a number of different options for tests that can find cancers early, before they start causing symptoms and before they’ve spread.

Some tests look at your stool (poop) to see if there are any signs of blood or antibodies linked to cancer, and these can be done once a year. Another stool test looks for changed DNA in the stool, and this can be done every three years.

The flexible sigmoidoscopy is when an HCP checks for polyps in the rectum and the last third of the colon. It’s usually a screening given every five years. The colonoscopy is the preferred screening test. It’s similar, but the HCP checks the entire length of the colon. Usually this is only done once every 10 years.

There’s even a type of colonoscopy that’s entirely virtual, using computers and X-rays. Talk with your HCP about your personal risk factors and about your preferences to determine which tests you choose and how often you get screened.