You may be avoiding having a colon cancer screening because you think it will hurt, or you may think it’s not needed. But you should know that, excluding skin cancers, colorectal cancer is the third most common type of cancer in Americans and the third leading cause of death from cancer in the U.S.

Screenings can catch it early when it’s treatable.

The growing number of people getting preventive screenings has brought the colorectal cancer death rates down, showing that screening really does work.

The Centers for Disease Control and Prevention and the U.S. Preventive Services Task Force recommend that everyone 45 to 75 years old get a screening. If you have a family history of the disease or have other conditions that could lead to colorectal cancer, your doctor may want you to get screened earlier.

How Does Colon Cancer Start?

Colon cancer usually begins with a growth called a polyp that develops in the inner lining of the colon. These polyps grow slowly over a period of many years. When polyps first start to develop, they are not cancer yet, but they have the potential to become cancer. The risk that a polyp will become cancerous increases as it gets larger.

Polyps can be removed easily before they have a chance to become cancer. Once a polyp does become cancer, it gets more difficult to treat.

Precancerous polyps and early colon cancer may not show symptoms. A screening test is the best way to prevent colon cancer or catch it early for a better chance at successful treatment.

What Are the Symptoms?

Since early colon cancer may not have any symptoms, screening is critical. By the time you develop symptoms, it may have grown and spread, making it harder to treat.

But there are some warning signs you can watch for, including:

• Anemia, which causes symptoms such as weakness, excessive fatigue and sometimes shortness of breath
• Bleeding from the rectum
• Blood in the stool or in the toilet after having a bowel movement
• Dark or black stools
• A change in bowel habits or the shape of the stool that isn’t caused by a change in diet
• An urge to have a bowel movement when the bowel is empty

What Are the Screening Options?

Colonoscopy is the most common preventive screening tool. A doctor uses a colonoscope — a flexible, lighted tube with an attached camera — to look at the entire rectum and colon for signs of cancer. The doctor can even remove precancerous polyps during the procedure, preventing you from getting cancer.

Some people may avoid a colonoscopy because it sounds painful. But the test is quick and painless. You are asleep during the procedure, and it takes less than an hour.

Other screening options are available, based on your doctor’s recommendation:

• A fecal occult blood test: A lab scans a stool sample for blood, a possible sign of cancer.
• Sigmoidoscopy: This procedure is similar to a colonoscopy, but it looks only at the rectum and the lower colon.
• Virtual colonoscopy: A CT scan supplies detailed images of the colon.

Early detection by screening is key. Catching it early gives you a better chance at successful treatment. Talk to your doctor about what screening options are best for you.

Can You Prevent Colorectal Cancer?

These healthy lifestyle tips may help to protect you from colon cancer:

• Eat a diet that’s high in fruits, vegetables and fiber.
• Stay away from red, grilled and processed meat.
• Avoid smoking, heavy use of alcohol and sedentary lifestyles.
• Exercise.
• Keep your weight in check.

Sources: Colorectal Cancer: Screening,  U.S. Preventive Services Task Force, 2016; Colorectal Cancer Facts & Figures 2020-2022,  American Cancer Society, 2020; Colorectal Cancer Statistics,  Centers for Disease Control and Prevention (CDC), 2020; What Can I Do to Reduce My Risk of Colorectal Cancer?,  CDC, 2021

Originally published February 12, 2020; Revised 11/2020, 2022