The importance of intestinal cancer screening

Barbara Turcott cherishes the time she spends with her family; time she says she would not have if it weren’t for a colonoscopy she had in 2008.

“I knew I was of the age when colonoscopy was recommended, and I had already put it off for four years. I knew it was time,” she says.

The colonoscopy detected spots on Barbara’s liver, which turned out to be a slow-growing type of cancer called carcinoid tumor. “I underwent surgery, and they took out two feet of my small intestine and 18 tumors in my liver.”

Barbara says the only noticeable symptom she had was flushed skin, something she never would have associated with cancer. Her gastroenterologist, Dr. Peter Kay with Eugene Gastroenterology Consultants, says that’s one of the reasons why colonoscopy screening is so important.

“Screening is essential if we’re going to catch intestinal cancers early,” he says. “Waiting for symptoms to appear may mean that the cancer is already there and may be more progressed or in an advanced stage.”

Symptoms of colorectal cancer

When symptoms of colorectal cancer appear, they likely vary, depending on the cancer’s size and location in the large intestine, but may include:

  • A change in bowel habits, such as diarrhea, constipation or narrowing of the stool, that lasts for more than a few days
  • A feeling that you need to have a bowel movement that is not relieved by doing so
  • Rectal bleeding
  • Dark stools or blood in the stool
  • Cramping or abdominal pain
  • Weakness and fatigue
  • Unintended weight loss

These symptoms may not indicate cancer, but they are concerning enough to discuss with your doctor to see if further examination and screening is warranted.

What is a colonoscopy?

A colonoscopy is an exam used to detect changes or abnormalities in the large intestine (colon) and rectum. During the procedure, a long, flexible tube called a colonoscope is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the entire colon.

If the doctor sees something that may be abnormal, small amounts of tissue can be removed for analysis, called a biopsy, and abnormal growths, or polyps, can be identified and removed. In many cases, colonoscopy allows accurate diagnosis and treatment without the need for a major operation.

When is a colonoscopy recommended?

It’s recommended that people at average risk of colorectal cancer start regular screening at age 45. However, if you have a family history of colon cancer or colon polyps in a first degree relative, your first colonoscopy should take place at age 40.

If your family history of colon cancer is in a first degree relative diagnosed before age 50, it’s recommended that your first colonoscopy should take place when you are 10 years younger than the age of your relative’s cancer diagnosis.

The importance of screening

Colonoscopy has been shown to be about 90% effective in both reducing the risk of getting colon cancer and detecting existing cancers. However, only about 60% of Americans who should be getting screened are doing so. Dr. Kay acknowledges that some of the apprehension in undergoing colonoscopy is due to the steps patients must go through to prepare for it.

A patient’s colon must be empty and clean for the doctor to get a proper look at it. The method recommended for most people is called split dosing, where the patient drinks half the dose of liquid laxative recommended in the evening prior to the colonoscopy, and then drinks the other half on the day of the procedure. It can be inconvenient and somewhat unpleasant, but Dr. Kay says the drink is more tolerable now and even comes in pill form.

Some patients worry that undergoing a colonoscopy will be painful, however, patients are sedated for the procedure. “Most people are asleep during the test and in fact, the most common thing we hear from patients when we’re finished is ‘When are you going to start?’” Dr. Kay says.

Prevention vs. detection

Colonoscopy is the only screening test that can prevent colon cancer, by spotting polyps early so they can be removed before they become cancerous. However, there are several types of tests that can detect abnormalities.

Testing at home

  • Fecal occult blood tests:

There are two types of fecal occult blood tests (FOBT) that detect blood in the stool, which can be a sign of cancer or precancerous polyps. It’s recommended the test be done each year and those with positive test results need to follow up, typically with a colonoscopy. The tests have been shown to detect up to 74% of intestinal cancers.

  1. Guaiac-based FOBT: During the test, you place a stool sample on a test card or flushable pad coated with a plant-based substance called guaiac. The card changes color if there is blood in the stool. Then, you send the card back to your doctor’s office or the lab for results.
  2. Fecal immunochemical test (FIT) or immunochemical FOBT: This test uses a specialized protein called an antibody, which attaches to hemoglobin, the oxygen-carrying part of red blood cells. A sample of the stool is placed in a tube or on a card and sent away to the doctor or laboratory for testing.
  • Multi-target stool DNA test (mt-sDNA): A newer at home test called Cologuard combines FIT with DNA markers indicative of cancer. The test can detect up to 92% of cancers; however, it’s only about 40-60% effective in detecting polyps and is much more costly. This test is recommended every three years.

Flexible sigmoidoscopy

A sigmoidoscope is a long, flexible tube that’s about half an inch in diameter. It has a tiny light and camera, and a doctor uses it to view the lining of the rectum and the lower third of the colon. A sigmoidoscopy is less invasive than a colonoscopy because it only looks at the lower part of your colon. The downside of sigmoidoscopy is that it can see only the left side of the colon and cannot detect colon cancers on the right side. This test is recommended every 5 years.

Virtual colonoscopy

Virtual colonoscopy is a special X-ray examination of the colon using low dose computed tomography (CT). It is a less invasive procedure than a conventional colonoscopy, takes 10 to 15 minutes to perform and does not require the use of anesthesia. However, patients still need to undergo a bowel prep (similar to colonoscopy), as well as drink a special contrast liquid before the test. The images from the virtual colonoscopy are reviewed by a radiologist who looks on the inside of the colon for polyps that can sometimes turn into colon cancer. Virtual colonoscopy is not good at detecting flat polyps (sessile serrated adenomas) which have a higher risk of turning into cancer. Virtual colonoscopy is recommended every 5 years.

Don’t put off screening

Barbara says the preparations she underwent for her colonoscopy pale in comparison to what she’s been through since she was diagnosed with cancer, including surgeries, diagnostic testing and continuous medication, and she urges everyone not to delay screening.

“Dr. Kay saved my life,” she says. “Just get in there and get it done, so you can have a chance. Don’t be afraid of it.”

Talk with your doctor about intestinal cancer screening options and learn more at