Your Complete Guide to Colon Cancer Screening and Prevention

Developing healthy habits, understanding symptoms, and getting screened can make a big difference in reducing your chances of getting colorectal cancer.

If you wrote a bucket list for the next decade, “get a colonoscopy” probably wouldn’t be on it. But screening for colorectal cancer should be one of your to-dos anyway: It’s the third most common and deadly cancer. It will affect 1 in 23 men and 1 in 26 women, according to the American Cancer Society (ACS). The older you get, the more likely it is that it will develop.

Unlike some medical conditions that have clear warning signs, colorectal cancer develops silently. The cancer may have already spread by the time you notice any symptoms, which makes it more challenging to treat, says Ashkan Farhadi, M.D. He is a gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, California. “The whole point of screening is to find polyps before they become cancerous,” he says.

If you dread the idea of getting a colonoscopy—and many of us do—the Food and Drug Administration (FDA) has approved gentler and less invasive screening tests too. Here’s what you should know about your colon cancer detection options, so you can decide with your doctor which one is right for you.

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What is colorectal cancer?

Colorectal cancer begins with a growth of cells that form in the lower end of the digestive tract. As you age, these small clumps of cells—called polyps—can grow in the lining of your colon or rectum. Some of these growths are harmless. Other polyps will become cancerous and may spread to other parts of the body.

What are the signs of colon cancer?

As we mentioned, it’s likely there are often no symptoms during the early stages of the disease. Over time, however, large polyps may start to bleed. At first, you may not notice it. But you may start to see blood in your stool as the cancer grows.

According to the ACS, other tell-tale signs include:

• Changes in bowel habits (diarrhea, constipation or narrow stools)
• Feeling you need to have a bowel movement, even though you just had one
• Abdominal cramping
• Weakness and fatigue
• Unintentional weight loss

What are the risk factors?

Colon cancer sometimes runs in families, but certain lifestyle factors also increase your risk of developing colon or rectal cancer, says the ACS. They include:

• Smoking. Cancer-causing particles in tobacco smoke can damage your DNA, causing abnormal cells to grow.
• Alcohol consumption. Exactly how alcohol ups your odds for cancer isn’t clear, but it may increase your risk by damaging cells.
• Diets rich in red and processed meat. Naturally occuring chemicals in red and preserved meat may be carcinogenic.
• Not eating enough fruits and vegetables. Diets that include a bounty of produce are associated with a lower risk of colon and rectal cancer.
• Obesity. Excess body fat can impact the way our cells grow.
• Lack of exercise. Not moving enough can lead to excess body fat too.

But even if you lead a healthy lifestyle, colon cancer can still develop, says Dr. Farhadi. “People tell me they don’t need to be screened because they don’t drink, smoke, or have a family history of cancer,” he says. “But sometimes there’s no rhyme or reason behind why someone gets colorectal cancer. That’s why colorectal cancer screening is your best prevention tool.”

What does a colorectal cancer screening test do?

When your healthcare provider screens you for colon cancer, they are looking for pre-cancerous and cancerous lesions in your colon and rectum. They want to find and treat those problems before you have symptoms.

Screening helps find cancer when it’s small, localized to the colon, and easier to treat.[4] At this stage in the disease, the survival rate is 90 percent. For people at average risk, the ACS recommends starting screening at age 45 and continuing through age 75.

Which screening tests are available?

To undergo screening for colon cancer, you have two choices: a colonoscopy or a stool test. Here are the details about each of them.

Colonoscopy

During this procedure, you are sedated and a physician inserts a flexible tube into your rectum.There is a light and a video camera on the end of the tube, which lets your doctor see your rectum and colon more clearly. If they find something that looks suspicious, your doctor will insert instruments through the tube to take biopsies (tissue samples) and remove polyps that they discover.

If they do find a polyp, don’t panic. It typically takes about ten years for a polyp to become cancerous, and they are usually removed during the procedure. But if they don’t find any abnormal cell growth, you can think of a colonoscopy as getting a “10-year warranty” on your colorectal health, says Dr. Farhadi.

This screening test is highly effective, but the prep before it isn’t pleasant. The colon needs to be empty to be effective. The day before the test, you’ll consume only liquids. The night before, you’ll take powerful laxatives to clear out your colon and rectum, making it easier for your doctor to see what’s going on.

Pros:

• If you don’t want to be sedated or undergo invasive scoping, ask your doctor if you’re a good candidate for computer tomography (CT). This test takes a picture of your colon and rectum. However, the same prep work is required for this test A colonoscopy provides a complete picture of your colorectal health.
• Your doctor can spot other health problems like ulcers or inflammation.
• If your colon is healthy, it only needs to be done once every ten years.

Cons:

• The test requires sedation.
• Fasting is required the day before the test, as are laxatives the evening before the procedure.
• A bloated, gassy feeling from the air pumped into your colon during the procedure.
• The test carries a small risk of bowel tears, infection or a reaction to anesthesia.

Stool Tests

These less-invasive screening tests pick up on the microscopic presence of blood in your stool. They can often be done at home, and you send your results to a lab. For some of these tests, you use a swab to collect a sample from one or more bowel movements. For others, you send the entire bowel movement.

Though they are not as thorough as colonoscopies, stool tests don’t require fasting or laxatives, says Robert Smith, Ph.D. He is the senior vice president of early detection science for the American Cancer Society.

“As you get older, it can be more difficult to go through the prep required for a colonoscopy, and the risk of complications increases,” Smith says. These tests are also a good option for people who have already had at least one colonoscopy.

If you’re considering stool testing, talk to your doctor about your options. More sensitive stool tests must be done once every three years, and less sensitive ones every year.

Pros:

• It can be done at home.
• No fasting or laxatives are required.
• It’s less invasive than a colonoscopy.

Cons:

• It must be done every one to three years, depending on the test.
• The test can miss some polyps, especially if they aren’t bleeding.
• You must follow up with a colonoscopy anyway if you test positive.
• It can result in false positives.

See our additional sources:
Diseases of the colon and rectum: The American Society of Colon and Rectal Surgeons
Colorectal cancer screening guidelines: Gastroenterology and American Cancer Society
Colorectal cancer screening tests: American Cancer Society and National Cancer Society
Colorectal cancer statistics: American Cancer Society
Tips to lower your risk for colon cancer: American Cancer Society

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