March 24, 2014

Colorectal Cancer Screening

By cancerconnect

When it comes to colorectal cancer, screening is prevention.

By Laurie Wertich

Michele Cofield, a 68-year-old retired schoolteacher from Buffalo, New York, is what you might consider a rule follower. She wears her seatbelt every time she gets in the car, undergoes regular mammograms, eats a healthy diet, and even remembers to schedule her 10-year follow-up colonoscopy. And it’s a good thing too because last July that 10-year colonoscopy revealed a 4 centimeter tumor at the base of her large intestine. After a biopsy indicated that the tumor was malignant, she was diagnosed with Stage I colorectal cancer and underwent surgery at the Roswell Park Cancer Institute to remove it.

Michele was lucky. Thanks to routine screening colonoscopy, the cancer was found early before it had a chance to spread. “I am a success story for screening colonoscopy,” Michele insists. “I scheduled my colonoscopy on time. I was not expecting to find malignancy in my colon, but it was there and it had been for a while.”

The experience reinforced what Michele already knew: screening works. What’s more, there are some new advances in colorectal screening that may make it easier—and less invasive—to stay on top of screening.

Colorectal Cancer

Colorectal cancer is the second-leading cause of cancer death in the United States. The American Cancer Society estimates that approximately 144,000 cases of colorectal cancer will be diagnosed this year and nearly 52,000 people will die from the disease.

But it doesn’t have to be that way. If more people underwent screening for colorectal cancer, we might see those numbers drastically decline. Unfortunately, it’s not that simple. Scheduling a colonoscopy falls pretty low on most people’s to-do list—just above having a root canal.

“There is no question that currently our biggest obstacle in colorectal cancer is the underutilization of screening,” explains Steven Nurkin, MD, MS, assistant professor of oncology in the Department of Surgical Oncology at Roswell Park Cancer Institute. “Approximately 40 percent of the US population is not getting screened—even though we know that screening works.”

Indeed it does. The results of a study published in the New England Journal of Medicine indicate that colonoscopy substantially reduces the risk of death from colorectal cancer.1

So, what gives? Why aren’t more people being screened? It’s complicated. There is a variety of factors at play, but perhaps the most important is a lack of awareness about colorectal cancer and the benefits of screening.

The Importance of Screening for Colorectal Cancer

Screening is an important component of preventive healthcare. Screening tests are designed to detect cancer early, before any symptoms arise, because this is when cancer is most treatable. Most women are vigilant about screening for cervical cancer (Pap tests) and breast cancer (mammograms), but many fall off the screening wagon when it comes to colorectal cancer, which is a shame because screening for colorectal cancer often means more than early detection.

“Screening is prevention,” insists Richard Goldberg, MD, physician-in-chief at the James Cancer Hospital and Solove Research Institute. “A colonoscopy is not like a mammogram, which is just early detection. It can prevent cancer.”

That’s because most colorectal cancers develop from abnormal growths in the colon or rectum called polyps. It takes about 10 years for a benign polyp to become cancerous, but removing polyps during a colonoscopy can actually stop cancer from forming. In other words, when it comes to screening for colorectal cancer, you could be killing two birds with one stone—because often the screening test is also a prevention tool.

Screening Tests for Colorectal Cancer

Most people assume that screening for colorectal cancer means undergoing a colonoscopy, but there is a variety of screening tests for the disease. Dr. Nurkin explains that the screening tests are divided into two categories: structural tests and stool tests. Structural tests, such as colonoscopy and flexible sigmoidoscopy, are used to examine the colon and identify polyps. Stool tests, such as the fecal occult blood test, examine the stool for blood and cancerous cells (see “Screening Glossary”).

The most common structural tests for colorectal screening are colonoscopy and flexible sigmoidoscopy. Colonoscopy allows physicians to view the entire colon, whereas flexible sigmoidoscopy allows visualization of only the lower part of the colon.

Although there are several different ways to screen for colorectal cancer, colonoscopy is the gold standard because it allows physicians to view the entire colon and remove polyps during the procedure. “No other screening method can do that,” Dr. Nurkin explains. “Any screening test is better than none, but colonoscopy is best.”

Some people prefer to have flexible sigmoidoscopy because it is less invasive, but Dr. Goldberg jokes that “having flexible sigmoidoscopy is sort of like getting a mammogram of only one breast because you’re looking at only part of the colon.”

Still, he says, “If the choice is between sigmoidoscopy and nothing, sigmoidoscopy is better than nothing.” In fact, a study published in the New England Journal of Medicine found that sigmoidoscopy screening can reduce the risk of developing colorectal cancer or dying from it—and it just might improve screening rates.2

Ironically, many of the less-invasive, easier screening tests lead to follow-up with colonoscopy screening anyway—so sometimes it makes sense to just do that in the first place.

What’s New in Colorectal Cancer Screening?

There are many new advances in the screening for colorectal cancer, as scientists continue to look for new and effective techniques—and hopefully tests that could result in higher compliance rates. Several promising tests have emerged in recent years, but none can be considered a standard screening procedure quite yet.

DNA stool test This screening procedure involves looking for abnormal DNA in stool samples. Changes in DNA occur as tumors develop in the colon. The tumors shed cells into the intestine, which makes it possible to detect the abnormal DNA cells in stool samples. This simple, noninvasive screening procedure has proven effective in some clinical studies but is still expensive to perform. “It’s sort of like looking for a needle in a haystack,” Dr. Goldberg explains. “To be most effective, it has to be performed repeatedly to have the most sensitivity.” Dr. Goldberg says that the test is continually being refined, but it has the potential to improve access to screening tests, especially in rural populations like Alaska, where residents can simply submit samples to a central laboratory via the mail.

Virtual colonoscopy Virtual colonoscopy (also called CT colonography) requires the same bowel preparation as traditional colonoscopy but uses a computed tomography (CT) scanner to visualize the large intestine. During the procedure spiral CT scanners scan the entire colon to produce a three-dimensional image. The procedure allows for the complete visualization of the colon more quickly and less invasively than with conventional colonoscopy, although if polyps are detected, the patient will still need to undergo conventional colonoscopy to have them removed. Virtual colonoscopy is a promising new technique, but more research may be needed before it becomes a standard screening procedure for colorectal cancer.

Blood tests Several researchers are involved with identifying a blood test that could help with the early detection of colon cancer. Onconome, Inc has reported results of studies on 431 patients based upon the blood test it has developed to determine an individual’s probability of having colorectal cancer (CRC). The results of the studies, published in the September 2012 issue of the American Journal of Cancer Research, demonstrate that the Onconome test is highly sensitive (93.75 percent) and specific (82.89 percent) and has a Negative Predictive Value of 99.9775 percent, meaning that a negative test result indicates an extremely low probability of a given patient having CRC. Additional clinical trials are now underway and are expected to be completed in 2013. (More information is available at

Screening Guidelines

Given so many choices for screening, how do you choose? That depends on many factors. The National Comprehensive Cancer Network (NCCN) provides colorectal cancer screening guidelines stratified by risk and screening type (see sidebar “What’s Your Risk?”).

The recommendations can get a little complicated because they consist of a lot of “If this, then this; if that, then that.” To follow the guidelines, you need to know your risk level and then follow the appropriate flowchart.

In general, the NCCN guidelines recommend that average-risk individuals begin screening at age 50 and then follow up accordingly based on the results of the test and the type of screening method used. For average-risk individuals with no polyps, colonoscopy should be performed every 10 years or sigmoidoscopy every five years. Increased-risk and high-risk individuals typically need to start screening earlier and sometimes undergo more-frequent screening (see “Screening Guidelines”).

Barriers to Screening

As if the complicated guidelines aren’t enough of a deterrent, there are several other barriers to screening.

Dr. Goldberg says that two of the most common barriers to screening, especially with colonoscopy, are lack of insurance and lack of a primary care physician. A colonoscopy is an expensive procedure, so people without insurance are less likely to have one. What’s more, it’s typically the job of the primary care physician to recommend a colonoscopy. Many uninsured people do not have a primary care physician, which means no one is reminding them to get this procedure.

But there are other, more surmountable barriers to screening: fear and embarrassment. There is a general sense of dread surrounding the idea of having a colonoscopy. The procedure is costly, time-consuming, and downright uncomfortable. It requires a commitment to cleaning out the colon (bowel preparation) prior to the procedure, which involves restricting the diet, drinking an unpalatable liquid to clear out the bowels, and staying near the toilet. The procedure itself isn’t so bad because it happens under sedation, but that means taking it easy for the rest of the day. As a result, people just feel a natural sense of resistance to the whole thing.

What’s more, it can be a little taboo to talk about our colons. “Some people feel embarrassed about the procedure,” Dr. Goldberg says. “But it’s far more embarrassing to die of a preventable disease than it is to have a colonoscopy.”

Just Be Screened

Fear and embarrassment aside, it’s important to just be screened. Because of her experience, Michele Cofield will forever be an advocate of colonoscopy screening. “You are in charge of your body,” she says. “It’s your life, so you should do everything in your power to make it the best life possible—including getting screened.

“Yes, the prep is not fun and, yes, it takes time out of your life and can be uncomfortable,” she adds. “But if you don’t have it, the risks involved are life-threatening.”

For Michele there is no question that the screening was worth every bit of inconvenience and discomfort.

“The only way we are going to have a dramatic impact on the outcomes of colorectal cancer is early detection and prevention,” Dr. Goldberg insists. “When colorectal cancer has spread to distant sites in the body, the average survival is two years, whereas when you catch a polyp that is just turning to cancer, there is a 90 percent survival rate.”

Dr. Goldberg says that good cancer prevention strategies for women include Pap tests, mammograms, and colonoscopy—as well as a healthy lifestyle, which goes a long way toward protecting against colon cancer and heart disease.

“Everybody should get a jug of GoLYTELY® [the bowel cleansing formula] for their fiftieth birthday,” jokes Dr. Goldberg.

Colorectal cancer is no joke. Just get screened.


1. Zauber AG, Winawer SJ, O’Brien MJ, et al. Colonoscopic polypectomy and long-term prevention of colorectal-cancer deaths. New England Journal of Medicine. 2012;366(8):687-96.

2. Schoen RE, Pinsky PF, Weissfeld JL, et al. Colorectal-cancer incidence and mortality with screening flexible sigmoidoscopy. New England Journal of Medicine. 2012;366(25);2345-57.

What’s Your Risk?

Average risk:

  • Age 50 or older
  • No history of colorectal cancer, precancerous polyps, or inflammatory bowel disease
  • No family history of colorectal cancer

Increased risk:

  • Personal history of colorectal cancer, inflammatory bowel disease, or polyps found during colonoscopy
  • Family history of colorectal cancer

High risk:

  • Family history of a hereditary syndrome associated with colorectal cancer
  • Personal history of 10 or more polyps
  • From a family that meets the Amsterdam II Criteria:
    • Three or more relatives have colorectal, uterine, or another Lynch-associated cancer, one of whom is a first-degree relative of the others
    • Two or more successive generations have cancer
    • One or more relatives diagnosed before the age of 50
    • Familial adenomatous polyposis has been excluded
  • From a family that meets the Bethesda Guidelines:
  • One relative diagnosed with colorectal cancer prior to age 50
  • Presence of any synchronous (at the same time) or metachronous (at another time) Lynch-associated tumors, regardless of age
  • Colorectal cancer with high microsatel-lite instability histology diagnosed in a patient under the age of 60
  • Colorectal cancer diagnosed in one or more first-degree relatives with a Lynch-associated tumor, with one of those cancers diagnosed before age 50
  • Colorectal cancer diagnosed in two or more first- or second-degree relatives with Lynch-associated tumors, regardless of age

Screening Guidelines

Screening guidelines vary based on risk level and screening outcomes. In general, the screening interval decreases if anything is found during screening. Some data indicate that African Americans are at an increased risk of colorectal cancer and therefore should start screening at age 45 rather than 50, even if they are considered average-risk. National Comprehensive Cancer Network guidelines recommend beginning screening in average-risk individuals at age 50.

Average-risk guidelines:

  • Colonoscopy is the preferred method. A negative colonoscopy should be followed by a repeat test in 10 years.
  • Stool-based tests of sigmoidoscopy are other screening options but should be repeated every five years.

Increased-risk guidelines:

  • Begin screening at age 40 or 10 years earlier than the age of diagnosis of a first-degree relative.
  • Guidelines are very nuanced depending on the individual risk profile. Those with low-risk polyps are recommended to repeat colonoscopy screening every five years; those with high-risk polyps are recommended to repeat colonoscopy every three years; and those with incomplete polyp removal are recommended to repeat colonoscopy within two to six months.

High-risk guidelines:

  • High-risk individuals may need to start colonoscopy screening as early as age 20 or two to five years prior to the age of a family member in whom the earliest colorectal cancer has been diagnosed.
  • Colonoscopy screening should be repeated every one to two years.

Screening Glossary

colonoscopy An outpatient procedure performed under sedation after thorough cleansing of the bowel. During the procedure a physician inserts a flexible tube attached to a camera through the rectum to examine the internal lining of the colon and the rectum for polyps or other abnormalities. If polyps are identified, they can be removed during the procedure. Colonoscopy is considered the gold standard in colorectal cancer screening because it allows for examination of the entire colon.

double-contrast barium enema?A test during which a physician inserts a chalky substance called barium through the rectum and into the colon and then takes X-rays of the colon and the rectum so that the area can be evaluated for polyps or other abnormalities. The barium helps open the colon so that the X-rays are more detailed and clear.

fecal immunochemical test (FIT) A newer type of fecal occult blood test that has been shown to be more specific and more sensitive. Unlike traditional FOBT, FIT does not require drug or dietary restrictions on the part of the patient.

fecal occult blood test (FOBT) A test that checks for hidden blood in the stool. If positive, this test indicates the presence of bleeding polyps and the need for further screening, such as colonoscopy.

flexible sigmoidoscopy An outpatient procedure that is performed without anesthesia or pain medication. A physician inserts a thin scope and a tiny camera into the rectum to examine the lower part of the colon. Sigmoidoscopy requires less bowel preparation than colonoscopy and is a fraction of the cost. It examines the lower third of the colon, which is where about half of all polyps and cancers develop.

What to Expect During a Colonoscopy

The anticipation of colonoscopy is often worse than the actual exam. Knowing what to expect can eliminate unnecessary anxiety. There are two phases of colonoscopy: the preparation and the exam.


Bowel preparation (cleansing) is a critical component of the procedure. It is important to clean out the colon completely because any residue can obscure the view of the colon and rectum during the exam. Bowel preparation varies slightly among different medical centers, but in general here’s what you can expect:

  • Five days before exam: Stop eating nuts and seeds. Stop taking iron supplements.
  • Two days before exam: Avoid vegetables, pulpy fruits, oatmeal and cereal with high fiber, nuts, and small seeds such as sesame seeds.
  • 24 hours before exam: Switch to a clear-liquid diet. Avoid solid food and alcohol until after the exam.
  • Bowel cleansing: The physician will prescribe a liquid cleansing solution that you will drink the evening before the exam. You’ll want to drink plenty of water and stay near the bathroom. Numerous trips to the bathroom can cause anal irritation. Speak with your doctor or nurse about tips for managing this irritation. Sometimes wiping with medicated wipes or swabbing the anus with petroleum jelly can help.

The Exam

The colonoscopy exam will take anywhere from 20 to 60 minutes. When you arrive at the medical center, you’ll sign consent forms and change into a hospital gown. In the exam room, you will be hooked up to an intravenous (IV) line as well as blood pressure and blood oxygen monitoring devices. The physician will deliver pain relievers and a sedative through the IV.

During the procedure you’ll be in “conscious sedation,” which is a pleasant, relaxed state in which you don’t feel a thing. In fact, you will likely have no memory of the procedure itself.

After the Exam

After the procedure you’ll be moved to a recovery room, where the IV is removed and you are given time to wake up. Most people feel fine after waking up. You might feel woozy or have a dry mouth, and you may have some gas that causes mild discomfort. You’ll be able to walk out of the medical center on your own, but you’ll need someone to drive you home as a result of the sedation. In fact, you’ll want to take it easy and avoid driving for the rest of the day.

Tags: Colon Cancer, colorectal cancer, News Tips and Features Other