One of the most important cancer screening procedure for colorectal cancer (CRC) prevention in people over 50 or those with high risk factors is a colonoscopy.The primary goal of a colonoscopy is to prevent deaths from colon cancer. Screening may help identify cancers at an early and potentially treatable stage. Some tests can also prevent the development of cancer by identifying precancerous abnormal growths called adenomatous polyps. In most cases, these polyps can be removed before they become malignant.

Of all cancers affecting both men and women, colorectal cancer, which includes both the colon (72%) and rectum (28%), is the second leading cancer killer in the United States. In 2007, the most recent year for which statistics are available, a total of 142,672 Americans were diagnosed with the disease (72,755 men and 69,917 women) [1]. The American Cancer Society estimates that 142,820 people will be diagnosed in 2013 and that 50,830 will die from colon cancer in the United States alone.

Risk factors
On average, the lifetime risk of developing colon cancer is about one in 20 (5%), however, this varies widely according to individual risk factors. People 50 years old or older, should get acolonoscopy because it can save their life. Statistics show that90% of new cases and 95% of deaths from colon cancer occur in people 50 or older. However, this cancer does not discriminate and can happen to men and women at any age. Also, while rates for colon cancer in adults 50 and older have been declining, incidence rates in adults younger than 50 years has been rapidly increasing.

Race may play an important role. People ofEastern European descent, including Ashkenazi Jews, may have a higher rate of colon cancer. Furthermore, partly because of disproportionate screening, African-American men and women have a higher risk of developing colon cancer and a lower survival rate (about 20% higher incidence rate and 45% higher mortality rate) compared to Whites, Asians, Hispanics and Native Americans.The risk of death is also increased for Native Americans and Alaskan Natives. Finally, people with a first-degree relative (parent, sibling, or children) who has colon cancer are between two and three times the risk of developing the cancer than those without a family history of colorectal cancer.

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A dreaded procedure
While colonoscopy is one of the most dreaded mid-life tests, it’s important because as many as 60% of deaths from colon cancer could be avoided through screening. “There are misconceptions about the screening,” explained gastroenterologistWendell K. Clarkston, M.D., from Saint Luke’s Hospitalin Kansas City, Mo,”But it’s not that difficult. Patients we’ve treated for pre-cancerous conditions are happy they had the test.”

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More about polyps
Colorectal cancer usually starts from polyps, a growth that over time could develop into cancer. Screening helps identify polyps so they can be removed, or find cancer early, when chances for cure are better. “People over age 50 are most at risk for developing colorectal cancer, and that risk increases with age,” Clarkston said. People at higher risk may need to start screening earlier than age 50. Risk may be higher than average if a patient has:

  • A close relative has had colorectal polyps or colorectal cancer
  • Has inflammatory bowel disease
  • Has a genetic syndrome such as familiar adenomatous polyposis or hereditary non-polyposis colorectal cancer

Symptoms of polyps or colorectal cancer include:

  • Blood in or on your stool (bowel movement)
  • Pains, aches, or cramps in the stomach that don’t go away
  • Losing weight for unknown reasons

Doctors recommend screening tests that can be used alone or in combination with each other. The U.S. Preventive Services Task Forcerecommendscolorectal cancer screeningfor men and women aged 50-75 using high-sensitivity fecal occult blood testing (recommend once a year) designed to detect blood or abnormal DNA markers [2], sigmoidoscopy (once every five years), or colonoscopy (once every 10 years). “Colorectal cancer is the second leading cancer killer, but it doesn’t have to be,” Clarkston noted. “People 50 years old or older, should talk with their doctor about getting screened.”

The guidelines from expert groups recommend that people should discuss the available options and choose a testing strategy that makes sense fort them. Often, being screened is more important than the kind of test used in the procedure.

Types of screening options
The available screening option include:

  • Colonoscopy (optical) –This test allows a physician to see the lining of the rectum and the entire colon. The testrequires a patient to prepare by cleaning out his entire colon and rectum. This usually involves consuming a liquid medication that causes temporary diarrhea. Before the procedure, a patient is given a mild sedative. During colonoscopy, a thin, lighted tube is used to directly view the lining of the rectum and the entire colon. Polyps and some cancers can be removed during this procedure. A colonoscopy detects most small polyps and almost all large polyps and cancers [3]. While relatively small, the risks associated with a colonoscopy are greater than those of other screening tests. Adverse events may include serious bleeding or a tear of the intestinal wall in some individuals (about 1 in 1,000). Because the procedure usually requires sedation, patients must be accompanied home after the procedure and should not return to work or other activities on the same day.
  • Sigmoidoscopy (optical;flexible) – A sigmoidoscopy allows a physician to directly view the lining of the rectum and the lower part of the (descending) colon. This area accounts for about one-half of the total area of the rectum and colon.Just as in the case of a colonoscopy, the procedure requires a patient to prepare by cleaning out the lower part of the bowel. However, the procedure is not as invasive. Cleaning out the lower part of the bowel usually involves consuming a clear liquid diet and using an enema shortly before the examination. Most people do not need sedative and are able to return to work or other activities the same day. During the procedure, a thin, lighted tube is advanced into the rectum and through the left side of the colon to check for polyps and cancer. This procedure is generally considered uncomfortable because it may cause mild cramping. Biopsies of small samples of tissue can be taken during sigmoidoscopy. One of the benefits of this procedure is that it may be performed in a doctor’s office.Sigmoidoscopy can identify polyps and cancers in the descending colon and rectum with a relative high degree of accuracy. Studies have shown that sigmoidoscopy reduces the incidence of colorectal cancer and overall mortality [4]. In comparison to colonoscopy the risks of sigmoidoscopy are small. In about 2 cases per every 10,000 the procedure may creates a small tear in the intestinal wall. Death from this complication is very rare. However, a major disadvantage of sigmoidoscopy is that it cannot detect polyps or cancers that are located in the right side of the colon.Research has shown that combining sigmoidoscopy with a fecal occult blood test (guaiac) is more effective than either test done alone.
  • Computed tomography colonography (CTC)or virtual colonoscopy –CTC is a test that uses a CT scanner to take two- and three-dimension images of the entire bowel. These images
    are reconstructed to allow a radiologist to determine if polyps or cancers are present. One of the major advantages of CTC is that it does not require sedation, is non-invasive, and the entire bowel can be examined. In most cases, abnormal areas (adenomas) can be detected as well as with traditional (optical) colonoscopy. However, there areseveral disadvantages of this procedure. Like traditional colonoscopy, CTC usually requires a bowel prep to clean out the colon. If an abnormal area is found, a traditional colonoscopy is needed at a later time fro diagnosis and a biopsy. Also, CTC may detect other abnormalities, unrelated to polyps and cancer, requiring further testing. Like many other imaging tests, this test exposes patients to radiation associated with long-term risks.

Fecal occult blood tests
Colorectal cancers often release microscopic amounts of blood and abnormal DNA markers into the stool. Two types of tests, called guaiac tests, such as a Hemoccult? FOBTtest, and immunochemical tests are designed to evaluate the stool for blood and recognize the DNA markers. If blood is present, this may be an indication of bleeding from colon cancer.

Guaiac testing requires a patient to collect two samples of stool from three consecutive bowel movements. After applying the results to a home collection card, the patient mails the cards back to his own healthcare provider. Generally, when performed once per year this test reduces the risk of colorectal cancer by as much as one-third [5][6]. However, because polyps seldom bleed, guaiac testing is less likely to detect polyps than other screening tests. Furthermore, only 2 to 5% of people with a positive stool test actually have colorectal cancer. If the stool test is positive, the entire colon needs be examined with a traditional (optical) colonoscopy. Relatively similar, immunochemical testing requires that a patient brushes the surface of his stool in the toilet. The brush is then applied to a card and mailed back to a laboratory.

Test results
In most cases, finding polyps or cancers in the lower colon increase the likelihood that there are polyps or cancer in the remaining part of the colon. Therefore, if a sigmoidoscopy reveals polyps or cancer, gastroenterologists recommend a colonoscopy to view the entire length of the colon.

Patient adherence: the physician’s role
When testing for colorectal cancer, the key factor for success is making sure that patients comply. Clinical studieshave shown that motivated patients compliance rates have been as high as 75%. [6][7] Furthermore, patients who understand the nature colorectal cancer are more likely to believe they may be at risk and will, in most cases, be more likely to participate in screening.Therefore, good communication between a physician and patients including effective use of educational materials makes a significant difference in patient participation and satisfaction with colorectal screening. [8][9][10]

In order to succeed, physicians need to be involved in educating their patients on colorectal cancer, explaining the lifetime risks for contracting the disease, and show them how it can be prevented through early detection. In addition to direct physician involvement, nurse practitioners, physician assistants, nurses, and other support staff also need to be educated on lifetime risk and the available prevention options, how screening should should be done, and how often patients need to be reminded.

Finally, after screening, each member of the healthcare staff has a unique roll to play in following up. For example, physicians need to make sure that patients with a positive FOBT, stool DNA, CTC or (optical; flexible) sigmoidoscopy are contacted for a follow-up exam. This last step is a crucial step in guaranteeing optimal care and reducing the incidence of colorectal cancer.

“Make That Call”
In February 2000, President Clinton officially dedicated March as the National Colorectal Cancer Awareness Month to promote activities designed to preventcolorectal cancer.Since then March has grown to be a true rallying point for the colorectal cancer community with a special campaign and activities designed to encourage screening.

Katie Couric(ABC Television), the Jay Monahan Center for Gastrointestinal Healthat theNewYork-Presbyterian Hospitaland the Entertainment Industry Foundation‘s (EIF) National Colorectal Cancer Research Alliance (NCCRA) are encouraging physicians to help their patients who are 50 years of age or as part of a high risk group to “Make That Call” and to get screened.

“With appropriate screening, colon cancer is often preventable and, when detected early, highly curable,” Couric said. “Colonoscopies save lives. That’s what ‘Make that Call’ is all about. Understanding that patients can take charge of their health.”

“So make that call, for yourself or someone you love,” encourages Couric, who’s husband died of the disease in 1998.

[1]U.S. Cancer Statistics Working Group.United States Cancer Statistics: 1999?2007 Incidence and Mortality Web-based Report. Atlanta (GA): Department of Health and Human Services, Centers for Disease Control and Prevention, and National Cancer Institute; 2010.
[2] Levin B, Lieberman DA, McFarland B, Andrews KS, Brooks D, Bond J, Dash C, Giardiello FM, Glick S, et al.Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology. 2008 May;134(5):1570-95. doi: 10.1053/j.gastro.2008.02.002. Epub 2008 Feb 8
[3] Rex DK, Cutler CS, Lemmel GT, Rahmani EY, Clark DW, Helper DJ, Lehman GA, Mark DG. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies. Gastroenterology. 1997 Jan;112(1):24-8.
[4] Atkin WS, Edwards R, Kralj-Hans I, Wooldrage K, Hart AR, Northover JM, Parkin DM, Wardle J, Duffy SW, Cuzick J. Once-only flexible sigmoidoscopy screening in prevention of colorectal cancer: a multicentre randomised controlled trial. Lancet. 2010 May 8;375(9726):1624-33. doi: 10.1016/S0140-6736(10)60551-X. Epub 2010 Apr 27
[5] Mandel JS, Bond JH, Church TR, Snover DC, Bradley GM, Schuman LM, Ederer F. Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study.N Engl J Med. 1993 May 13;328(19):1365-71[Full article]
[6]Gaudion, John R.Colorectal Cancer Screening in America: An Industry PerspectivePoint of Care: The Journal of Near-Patient Testing & Technology. 1(1):28-29, March 2002.
[7] Paaso, B.T., Community-based colorectal cancer screening. Point of Care, 2002; 1(1):20-27.
[8] Bond, J.H., and Burt, R.W., How to increase colorectal screening rates, Patient Care. February 15, 2002, pp 32-39.
[9]Ling BS, Moskowitz MA, Wachs D, Pearson B, Schroy PC. Attitudes toward colorectal cancer screening tests. J. Gen Intern Med. 2001 Dec;16(12):822-30.
[10] Sarfaty M.How to Increase Colorectal Cancer Screening Rates in Practice:A Primary Care Clinician?s. Evidence-Based Toolbox and Guide2008 (Thomas Jefferson University) [Download]

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