The Importance of a Screening Colonoscopy

If you knew that the majority of deaths from colorectal cancer could be prevented if every adult 50 years or older got tested, would you do it? Unfortunately, that message falls on deaf ears for millions of us.

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If you are turning 50 this year, be prepared to give one special birthday present to yourself – a screening colonoscopy. It may not be what you had in mind to celebrate this milestone birthday, but there are 50,000 reasons why you should consider it. That's the number of people that will die each year from colorectal cancer. It is the 2nd leading cause of cancer-related death, but it needn't be.

How, you might say, can a test that is uncomfortable, invasive, embarrassing and time-consuming be called a gift? Because a screening colonoscopy can expose a cancerous tumor currently under way, and shed light on the changes that might precede it. And by intervening early you can nip those changes in the bud, long before those potentially menacing cells become malignant.

And that's a gift worth getting.

The Centers for Disease Control and Prevention (CDC) estimates that 22 million adults ages 50-75 still need to be tested.

How Does Colorectal Cancer Play Out?

The large intestine is the last organ in the gastrointestinal system picking up where the small intestine leaves off. It is charged with removing water from the leftover solids of digestion and eliminating it as stool. Cancer can form anywhere inside the 5-foot tube that squares the abdominal cavity.

The large intestine extends up on the right side (ascending colon), making a left turn past the liver and across (transverse colon), bending down at the spleen on the left (descending colon), looping to the middle (sigmoid colon) before passing through the rectum and out the anus. (The cecum and appendix balloon off the ascending colon just below the juncture between the colon and small intestine.)

The cells lining the colon are constantly growing and dying in a natural process of cell turnover. If the cells' growth message system fails from faulty or unstable genes, the cells can grow unchecked into a mass of tissue called a polyp. As the cells continue to divide and grow, they can become more and more abnormal. You probably won't feel them growing or have any noticeable symptoms that let you know they are there.

Mostly these changes are benign polyps (adenomas), a seemingly harmless bump or tag. But these polyps can also take a turn for the worse and transform into an advanced adenoma or cancerous mass that can not only narrow or block the opening of the tube, but also breakthrough the wall to invade nearby lymph nodes and travel to metastasize elsewhere in the body. Since you won't know if and when they will become a threat, you need to get them removed.

Finding and removing benign polyps can reduce the risk of colon cancer substantially and finding and removing cancer early, at a more curable stage, can save lives. Nearly, 25% of 50 year olds develop polyps and 5% of these are cancerous.

Who is at Risk for Colorectal Cancer?

To put it simply, all adults are at risk for colorectal cancer, even those that live healthily.

Some people are at very high risk. They have a particular gene mutation that predisposes them to developing multiple polyps.  These are hereditary syndromes such as familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer syndrome and MutY homolog (MUTYH) polyposis.

The risk is also high, almost doubled, in people with a diagnosed first-degree relative (mother, father, sister, brother, child), especially if the relative was diagnosed before the age of 50. Ulcerative colitis and Crohn's disease, types of inflammatory bowel diseases, also up the risk.

But average folks can also be at higher risk too, especially if they partake in some unhealthy lifestyle behaviors.

Lifestyle risk factors for colorectal cancer

  • Diets high in fat or low in fiber, calcium, or both
  • Obesity
  • Physical inactivity
  • Tobacco smoking
  • High alcohol intake

What Screening Tests are Available to Detect Colorectal Cancer?

For a screening test to be affective it should be able to predict with some degree of confidence that a person has cancer long before a sign or symptom appears. In the case of colorectal cancer there are a few types of screening tests that can be used alone or in combination with each other. At this time, many professional organizations view colonoscopy as the gold standard.

Stool Tests

Blood in the stool can occur when a polyp or tumor pulls away slightly from the intestinal wall as stool moves past it. Although frank red blood may streak stool, you can't be sure if it is caused by something worrisome, or a benign condition such as hemorrhoids. Still, blood is not always visible to the naked eye, so doctors use a test that detects hemoglobin, a protein that is found inside a red blood cell. Three consecutive stools are tested.

There are 2 types of blood detection tests, guaiac fecal occult blood test (FOBT), which detects any hemoglobin human or animal, and fecal immunochemical test (FIT), which is more specific for human blood. The tests can be performed at home.  A positive test suggests that bleeding is occurring somewhere in the lower GI tract, a red flag for colorectal cancer. This test should be performed once a year.

You either smear a stool sample on a test card you get from your doctor or pharmacy and mail it back to a lab, or apply a chemical yourself and report the results. Although it is a simple test to perform and is non-invasive, it has a low sensitivity for detecting polyps and advanced adenomas. Red meat, broccoli, turnips, radishes, citrus, horseradish and certain drugs and supplements can make the guaiac test positive when it is not.

The stool DNA test is a new test still undergoing development and is available by not yet approved by the Food and Drug Administration (FDA). It detects certain biochemical markers characteristic of many different colon cancer types. The DNA damaged cells containing the markers are shed into stool, which you collect and send back to a lab for analysis.

 

Endoscopy Tests

Doctors often rely on an endoscope to visualize the inside of the body. A long flexible tube fixed with a tiny fiber optic camera is threaded into an opening to illuminate and magnify the tissue while it is displayed on a computer screen. There are 2 procedures that visualize the colon using endoscopes, a colonoscopy and a sigmoidoscopy.

Sigmoidoscopy is only able to visualize the lowest portion of the colon and the rectum. People undergoing this procedure are asked to stay on a liquid diet for a day or so and on test day receive a couple of flushing enemas so the doctor can see the lining of the colon unobstructed. This procedure doesn't require sedation and can be performed in the doctor's office. If a polyp is found, it can be removed during the procedure and sent to a pathologist for review.

Colonoscopy is more commonly recommended because it can visualize the whole length of the large intestines and is able to look up, across and down the length of the colon. This procedure however requires more preparation, sedation and carries more risks such as perforation and bleeding.

Bowel preparation techniques vary but the goal is the same, to rid the colon of any stool so that there is nothing obstructing the doctor's view. Bowel prep begins a few days before progressing to a liquid-only diet, and is followed by a bowel prep solution or strong laxative enema the night before the test. An improperly prepared colon can block polyps and other abnormalities, so following the prep directions carefully is critical. You will be awake, but sedated enough to be comfortable. You may experience cramping when the doctor manipulates the scope and instills air into the colon to better navigate the twists and turns.

Again, if a polyp or abnormal looking tissue is found, it is removed or biopsied during the procedure and later analyzed by a pathologist who will generate a report to give to your doctor. 

Capsule endoscopy (PillCam) is a non-invasive method that might be a viable option in the future for people unable or unwilling to undergo standard colonoscopy. A person swallows a battery-powered capsule that has an endoscopic camera on both ends. A video of the 10-hour trip down the digestive tract is generated before it exits the body. Unfortunately it can miss a lot and it doesn't have the accuracy of doctor-guided colonoscopy, who can manipulate the device to get sight of hard to reach corners. Bowel prep is required and critical to finding masses, and a standard colonoscopy will be required to remove any found polyps.

 

X-rays and CT scans

Virtual colonoscopy (computerized tomographic colonography) is a new type of screening method that uses a CT scanner to visualize the colon. A device is inserted at the rectum but does not ascend up past the sigmoid portion of the colon. It is less uncomfortable but a colonoscopy will still be required if a polyp is found. Bowel prep is still necessary. 

Double-contrast barium enema is a type of X-ray that can provide an image of the bowel after both a cleansing enema and an enema containing the contrast material is introduced into the rectum. As the barium coats the lining, an outline of a mass can be seen on the X-ray image. If anything is detected, colonoscopy is required.

Here are some guiding principles to live by

  • If you are experiencing bleeding, a change in the frequency and characteristics of your bowel movements (such as skinny stool), abdominal pain or unexplained fatigue, cramping or weight loss, go to the doctor as soon as possible
  • If you are 50, undergo an endoscopic procedure, preferably a screening colonoscopy
  • If you have personal risk factors such as colorectal cancer or adenomatous polyps detected in a first-degree relative before age 60, begin screening sooner (typically at age 40)
  • Continue getting a colonoscopy every 10 years; or a flexible sigmoidoscopy, double-contrast barium enema or virtual colonoscopy every 5 years; and a fecal occult blood test every year
  • If you have had a polyp detected and removed, get screening colonoscopy more frequently as recommended by your doctor
  • If you don't have insurance, or your insurance won't cover the costs, locate a free or low-cost screening program in your area via CDC's Colorectal Cancer Control Program
  • Adopt a mostly plant-based diet, stay physically active, don't smoke tobacco, maintain a healthy weight, and limit processed grains and alcohol (no more than 2 drinks per day)

To Find More Information on Colorectal Cancer

American Cancer Society (ACS)

Centers for Disease Control and Prevention (CDC)
National Cancer Institute (NCI)
The Jay Monahan Center for Gastrointestinal Health
American Society of Clinical Oncology (ASCO)

To Find a Gastroenterologist
American College of Gastroenterology
American Society of Gastrointestinal Endoscopy

To Find Colorectal Cancer Support
American Cancer Society
Cancer Care, Inc.
Colon Cancer Alliance