A Complete Guide to Colon Cancer Screening: Overview, Benefits

A Complete Guide to Colon Cancer Screening: Overview, Benefits

Even if you don't know much about colonoscopies, you probably know that they aren't much fun. I'm not here to convince you otherwise. However, I do want you to know that colorectal cancer screening is absolutely imperative. These tests have the potential to save your life because they can catch cancer early on or before it is even fully developed.

What exactly is a colonoscopy? Is it the only screening for these cancers? Who needs a colon cancer screening? Read on to find out!

What Does Screening Involve?

There are two different categories of tests used to screen for colon cancer. One type looks for both cancer and pre-cancerous polyps. The other type looks only for cancer.

Tests for Polyps and Cancer

The sooner that colon cancer is identified, the better. In fact, if it can be caught before it fully develops, that is best. That is why many doctors recommend undergoing a screening that can identify not only cancer but also polyps.

Polyps are growths that can develop into cancer. If a screening detects polyps, a doctor can remove them before they become cancerous.

Screenings that study the inside of the colon can find spots with polyps or cancer. These include:

This is the most well-known colon cancer screening. The doctor uses a lighted scope to look at the inside of the colon. Often, polyps found during this test can be removed right then. This is one of the most accurate tests, so it is often used as a follow-up to other screenings.

  • Flexible sigmoidoscopy:
    For sigmoidoscopy, the doctor uses a smaller scope than in a colonoscopy. Instead of examining the whole length of the colon, this test looks at only the rectum and the colon's first third. Polyps can sometimes be removed in conjunction with this procedure.
  • ​CT colonography:
    In this high-tech test, which is less invasive than a standard colonoscopy, a CT scanner takes multiple x-rays. The images are compiled into one picture to give the doctor a full look at the inside of the colon.
  • Barium enema:
    This is one of the least common screenings for colon cancer. It involves putting air and barium sulfate into the colon. Then, the doctor takes an x-ray. The materials that were inserted into the colon help define its lining on the x-ray so problem areas can be noted.

These screenings require the patient to prepare the bowels. The individual takes strong laxatives or uses an enema to clean out the colon so the doctor will be able to get a good look at it during the test.

Colonoscopy is the only one of the above tests that typically requires the patient to undergo sedation.

Tests for Cancer Only

Some colon cancer screening tests look only for cancer that has already developed. Because these tests analyze stool samples, they are less invasive than other tests. However, they cannot detect the presence of polyps.

These tests include the following options:

  • Fecal immunochemical test: The FIT screening looks for blood in a small fecal sample. It uses antibodies to detect the presence of blood.
  • Guaiac-based fecal occult blood test: A gFOBT test also looks for the presence of blood in a small stool sample. The blood is identified with a chemical called guaiac.
  • FIT-DNA: This test is similar to the FIT test, but it requires a full stool sample. In addition to testing for antibodies, the test also looks for unusual DNA in the sample.

For Whom Is Screening Recommended?

Experts recommend that adults between the ages of 50 and 75 undergo regular screening for colorectal cancer. After age 75, individuals and their doctors can decide together whether continued screening is necessary.

If you have a family history of colorectal cancer, these guidelines are different. Consider the youngest age that anyone in your family was diagnosed, and begin screenings 10 years before that age.

Stool tests for cancer should be performed annually. However, the more invasive tests--if they come back with normal results--need to be repeated only every five years or more. In fact, colonoscopies need to be done only every 10 years. If done in conjunction with annual FIT-DNA tests, the time between sigmoidoscopies, too, can stretch to 10 years.

What Are the Benefits of Screening?

Colorectal cancer is one of the top four most-diagnosed cancers in the United States. Unfortunately, many people who have colon cancer do not show any symptoms until the disease has progressed significantly.

Colon cancer screening can detect the disease before the manifestation of symptoms. The sooner cancerous or pre-cancerous growths are spotted, the sooner they can be treated. Early detection can improve outcomes, particularly because colon cancer is usually slow to develop.

In fact, if colon polyps are found before they become cancerous, they can be removed. This prevents them from ever turning into cancer.

Colonoscopies and other screenings save lives! Talk to your doctor about which tests you should have and when. If you have other questions, please comment below.

  • Begin screening at age 50--sooner if you have a family history.
  • A colonoscopy is the most thorough test. Have one of these or another cancer and polyp screening every five to 10 years.
  • Stool screenings should be repeated annually.
Brian Chandler

Brian Chandler

Raisa Delima - September 19, 2017

I’m glad you said to start screening at age 50 for colon cancer. My father is 52, and I don’t think he has gone in for a screening yet, so I will have to tell him to do that soon. I really don’t want him to have issues that could be handled easily if he would just go in to a professional, so I’ll have to make sure he does it.

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