Can colorectal cancer be prevented?

In some cases, yes. Colorectal cancer often begins as a growth called a polyp inside the colon or rectum, and finding and removing polyps can prevent colorectal cancer.

This is why checking for polyps matters. Removing a polyp before it becomes cancer is a chance to stop that cancer from ever forming.

That makes colorectal cancer unusual. Most cancer screening finds disease early. Colon screening can keep the disease from ever starting. A polyp is not cancer. It is a small mound of extra tissue on the bowel lining. Many polyps never change at all. Some slowly pick up genetic damage over years and turn into cancer. Taking one out during a colonoscopy ends that process for good. The National Cancer Institute notes that removing colorectal polyps larger than 1 centimeter may lower risk.

Screening tests can be used to detect colorectal cancer and polyps. These tests give a healthcare team a way to look for polyps and cancer, sometimes before symptoms appear.

Age sets the starting line. The US Preventive Services Task Force recommends screening all adults aged 50 to 75. That carries a grade A, its strongest rating. It also recommends screening adults aged 45 to 49, at grade B. From 76 to 85, screening becomes an individual choice based on your health and your past tests.

Several tests count, and any of them beats doing nothing:

• FIT (fecal immunochemical test), a stool test, every year
• High-sensitivity guaiac stool test, every year
• Stool DNA-FIT, every 1 to 3 years
• Colonoscopy, every 10 years
• CT colonography, every 5 years
• Flexible sigmoidoscopy, every 5 years, or every 10 years paired with a yearly FIT

Only colonoscopy both finds and removes polyps in the same visit. The rest only detect. A positive result on any stool test or scan still means a colonoscopy afterward. People miss this step surprisingly often. Skipping it undoes the whole point of the screening test.

Habits shift the odds too. Smoking raises risk. So does drinking 3 or more alcoholic drinks a day, and so does carrying extra weight. Regular physical activity is linked to lower risk. Whether a low-fat, high-fiber diet helps is still unsettled, and NCI says plainly that it is not known.

Aspirin is the one place where good sources disagree, so here is the state of it. NCI reports that taking aspirin daily for at least two years lowers colorectal cancer risk. The US Preventive Services Task Force looked at the question again in 2022 and concluded the evidence is inadequate that low-dose aspirin reduces colorectal cancer cases or deaths. It removed colorectal cancer from its aspirin recommendation and now advises against starting aspirin at age 60 or older. Aspirin also causes bleeding. Do not start it for cancer prevention on your own.

Some people need to start earlier and repeat more often. Having a parent, brother, sister, or child with colorectal cancer doubles your risk. Inherited conditions such as Lynch syndrome and familial adenomatous polyposis raise it far more, and so does long-standing inflammatory bowel disease. If any of these fit you, the average-risk schedule does not apply.

Your healthcare team can explain which screening options may be right for you and when to have them. Pick the test you will actually finish. A yearly stool test done every year beats a colonoscopy you keep postponing. And do not wait for a screening age if you have symptoms. Blood in the stool, a lasting change in bowel habits, or unexplained weight loss should be checked now, at any age.