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Colorectal Cancer

Risk, Screening and Referral

Vol. 17 • Issue 12 • Page 19
Continuing Education

Continuing Education Offering: The goal of this article is to educate nurse practitioners about colorectal cancer. Nurse practitioners may obtain 2 contact hours by reading this article and earning a passing score on the test that follows. For immediate test results, take the quiz online at The author has completed a disclosure statement and stated no real or perceived conflicts of interest.

How to Obtain Contact Hours by Reading This Article

Instructions: Nurse practitioners may receive 2 contact hours by reading the article noted below and earning a passing score on the accompanying quiz. To obtain contact hours:

1. Read the article "Colorectal Cancer. Risk, Screening and Referral," carefully noting the tables and other illustrative materials provided to enhance your knowledge and understanding of the content.

2. Read each question, and record your answers on the registration form provided.

3. Fill out the evaluation portion completely. You will not receive CE credit if this section is not completed.

4. Type or print your full name and address in the space provided on the registration form.

5. Forward the completed registration form with your check or money order for $10.00 payable to Merion Publications, or provide your credit card information. Quizzes are accepted up to 24 months from publication.

Continuing Education Credit: Merion Publications Inc. is approved as a provider of continuing education in nursing (Provider #008-0-07) by the Pennsylvania State Nurses Association, which is accredited as an approver of continuing education in nursing by the American Nurses Credentialing Center Commission on Accreditation, the California Board of Registered Nursing (Provider #CEP 13230) and the Florida Board of Nursing (Provider #CEP 3298). California and Florida participants must retain certificates for 4 years.

You will be advised of your score within 30 to 60 days. A score of 70% or above is passing grade. A certificate will be awarded to participants who pass. Participants who score less than 70% can retest one time for no additional charge. No refunds.

Objectives: The purpose of this article is to educate nurse practitioners about colorectal cancer. After reading this article, the nurse practitioner should be able to:

• identify the most common type of colorectal cancer

• state the ethnic groups at highest risk for colorectal cancer, as well as incidence by gender

• explain how to stratify patients into risk categories

• discuss types of screening methods, prevention and when to refer patients to a specialist.

Directions: On the registration form, check the box next to the best answer.

Colorectal cancer is the third leading cause of cancer death in the United States, and it accounts for approximately 10% of all new cancer diagnoses.1More than 146,000 new cases were diagnosed this year, and an estimated 49,920 deaths occurred as a result of the disease.1

Colorectal cancer occurs in the large intestine and rectum. Most colorectal cancer is adenocarcinoma. Two other common types of adenocarcinoma are mucinous or colloid carcinoma and signet ring cell carcinoma. Less common are squamous cell, adenosquamous and small cell carcinoma. The natural progression of colorectal cancer starts with epithelial dysplasia and is followed by adenomatous polyp, which eventually progresses to adenocarcinoma.2,3


Colorectal cancer does not disproportionately affect a particular gender or ethnic group. Risk for this type of cancer stratifies both sexes and all races. However, race plays an important role in risk.4In both men and women, blacks experience the highest incidence of colorectal cancer by race (Table 1).4

Colorectal cancer risk among men is 6% (1 in 17). Among women, the risk is 5.5% (1 in 18). The risk of death from colorectal cancer among men is 2.29% (1 in 44), and the risk among women is 2.13% (1 in 47).5The incidence of colorectal cancer has decreased steadily over the last 2 decades. This is believed to be a result of increased screening, better awareness and improved removal of precancerous polyps.1Awareness campaigns by public figures have helped increase colorectal cancer screening. After TV news anchor Katie Couric, whose husband died from colorectal cancer, underwent a colonoscopy on live television in March 2000, researchers documented a significant increase in screening.6

Stratifying Risk and Screening

The American Gastroenterological Association (AGA) published comprehensive guidelines for the diagnosis and treatment of colorectal cancer in 2004. This document establishes a basic guide for stratifying patients according to risk.7Risk stratification begins with a complete physical examination and history. Include questions about weight loss, anemia and changes in bowel habits. The personal medical history must determine smoking status and history, plus history of ulcerative colitis, Crohn's disease, inflammatory bowel disease (IBD) or cancer.8For the family history, ask about colorectal cancer, adenoma, and genetic syndromes such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). The answers to these questions determine stratification into risk groups (Table 2).

Average-risk patients who are older than 50 and present without symptoms or personal or family history of colorectal cancer should be offered screening. Several modalities are available to screen for colorectal cancer. The American College of Gastroenterologists recommends colonoscopy as the primary screening tool, but other organizations are not as specific.9Clinical guidelines based on a systematic review of data from the U.S. Preventive Services Task Force provide plentiful information on colorectal cancer screening choices.10Screening tests for colorectal cancer include fecal tests, fecal guiac, fecal DNA, computed tomography (CT) colonography (virtual colonoscopy), flexible sigmoidoscopy and colonoscopy.11-14

Patients considered at increased risk should begin screening colonoscopy by age 40. Patients who have a personal history of adenomas fall into two categories and screening is recommended as follows:

• adenoma less than 1 cm and fewer than one or two polyps, colonoscopy every 5 years

• adenoma greater than 1 cm and more than three adenomas, colonoscopy every 3 years.

Patients with a personal history of colorectal cancer should have colonoscopy annually. If the results are clear, it is appropriate to schedule colonoscopy every 3 to 5 years as long as results are normal.7,8

Patients at high risk include people with inflammatory bowel disease or genetic syndromes linked with colorectal cancer risk. These genetic syndromes include FAP, HNPCC, Lynch syndrome, Muir-Torre syndrome and Turcot syndrome. Genetic syndromes account for 1% to 3% of all colon cancers in the United States.15

Patients who are identified as high risk should be referred to gastrointestinal specialists for close observation and surveillance. For patients with HNPCC, screening often begins between the ages of 20 and 25. For patients with FAP, screening may begin as early as age 12.15

Types of Screening Methods

Within the gastroenterology community, screening choice is a subject of debate. The AGA has taken the position that many tests can effectively screen for colorectal cancer.7That said, use screening tests that best meet each patient's needs (Table 3).

This section provides a brief review of available screening tests - enough to make appropriate decisions according to evidence-based practice and the needs of individual patients. Screen all patients for colorectal cancer on an ongoing basis.

Fecal testing for colorectal cancer screening encompasses three types: traditional fecal occult blood test (FOBT), fecal immunochemical and DNA fecal markers. In hemoccult testing, the patient uses a collection kit to perform testing on three stool samples. Dietary restrictions are in place at the time of testing. The patient mails the completed cards or submits them to a local lab for analysis of hemoccult blood.10FOBT has a high false-positive rate, but it is used on a widespread basis to screen for colorectal cancer in primary care settings. Detection rates range from 25% to 90%.1sup>2

Positive results on FOBT are reported as 2% to 9% in the general population, with approximately 5% of these patients having colorectal cancer. But 30% of these patients may have precursor adenomas or precancerous tissues detected with follow-up of the positive FOBT.11,12In one study, patients who demonstrated a positive FOBT and underwent further testing with full colonoscopy or flexible sigmoidoscopy were diagnosed with less serious conditions or had normal findings.11This type of testing is common in primary care and is effective if used correctly. FOBT is considered a highly accurate marker of colorectal cancer presence.11,12Patients who have a positive FOBT are automatically referred for colonoscopy.

Immunochemical fecal testing requires two stool samples and does not impose dietary restrictions. Four types of immunochemical fecal testing are available, and three are approved for use in the United States. Positive test results require full colonoscopy.7,10

DNA fecal testing identifies any of 21 DNA markers in a stool sample. Fecal samples are analyzed similarly to traditional FOBT. In a 2004 study, FOBT and DNA fecal testing were compared in average-risk patients older than 50.13DNA testing was superior to traditional FOBT in detecting high-grade dysplasia and advanced neoplasia. Findings were subsequently confirmed with traditional colonoscopy.13Virtual or CT colonography has gained more acceptance as a colon cancer screening test. CT colonography is essentially an x-ray of the colon. Patients must do a complete bowel preparation (evacuation) for this test, which is performed only at a radiology center. The procedure takes approximately 15 to 25 minutes and requires the patient to lie flat and change positions on the table at various times during the procedure. A disadvantage of this procedure is that traditional colonoscopy must be initiated if polyps or other pathology are noted. Another disadvantage is that smaller, flat lesions and polyps less than 6 mm are often missed on this type of study.9,14

Flexible sigmoidoscopy examines the descending colon. The AGA recommends combining flexible sigmoidoscopy with FOBT for screening. Flexible sigmoidoscopy can be performed after a simple bowel preparation (enema) and can be done in the office with little or no sedation. FOBT must be completed prior to the procedure, because positive results would prompt a full colonoscopy rather than flexible sigmoidoscopy.9

Colonoscopy is commonly used as a screening tool for colorectal cancer. The AGA recommends offering screening every 10 years to patients 50 and older. This method of screening provides full evaluation of the entire colon as well as the ability to remove polyps and take biopsies of identified flat lesions or suspicious areas.9 nesthesia is required, which presents some risk to patients. The procedure also requires complete bowel preparation. Visualization of the entire colon can be hampered by poor bowel preparation and navigation of the colon itself. However, colonoscopy is the preferred method for screening of patients who are good candidates for it, and it is required for patients who are at risk or who have had positive screening results on lesser tests such as FOBT.9


Prevention of colorectal cancer begins early in adult life. Three approaches are effective: lifestyle modifications, early detection and screening, and chemoprevention (Table 4).7.9.16

Specialist Referral

Patients should be referred to GI specialists in particular circumstances, including the following:

• risk stratification results

• positive screening test results

• age older than 50

• presence of identified genetic family history patterns.

In addition, any patient who presents with GI bleeding, positive FOBT, hematochezia, iron deficiency anemia, unexplained weight loss, or melena with a negative esophogastroduodenectomy should be referred to a GI specialist for colonoscopy without delay. Regardless of age, patients who are stratified at high risk require automatic referral to a GI specialist for regular monitoring.7,9,10

Putting It Into Practice

Numerous tools are available to assist in improved diagnosis of colorectal cancer. The American Cancer Society provides a free tool at The tool was updated this year to be more inclusive of various races.17This user-friendly assessment tool helps determine risk and can be used as a teaching method for reducing risk.

As with any screening, options must be presented in a way that will meet individual needs. Risk stratification should be made through careful and thorough history taking and physical examination at regular intervals. Screening can only be effective if it takes place, regardless of the modality used. Open communication about risks and benefits is the most useful strategy.


1. Cancer Facts and Figures 2009. American Cancer Society. Available at: Accessed Aug. 27, 2009.

2. National Cancer Institute. Colon and Rectal Cancer. Available at: Accessed Aug. 27, 2009.

3. Jennings-Dozier K, Mahon SM. Cancer Prevention, Detection, and Control: A Nursing Perspective. Pittsburgh, Pa.: Oncology Nursing Society; 2002.

4. Centers for Disease Control and Prevention, United States Cancer Statistics. Available at: Accessed Aug. 27, 2009.

5. Lifetime probability of developing or dying from cancer. National Cancer Institute Surveillance Epidemiology and End Results (SEER) Database. Available at: Accessed Aug. 27, 2009.

6. Cram P, et al. The impact of a celebrity promotional campaign on the use of colon cancer screening: the Katie Couric effect. Arch Int Med. 2003;163(13):1601-1605.

7. Burt RW, et al, eds. Preventing Colorectal Cancer: A Clinician's Guide. Bethesda, Md.: American Gastroenterological Association; 2004.

8. CRICO/RMF Colorectal cancer screening algorithm. Available at: Accessed Aug. 27, 2009.

9. Rex DK, et al. American College of Gastroenterology Guidelines for Colorectal Cancer Screening 2008. Amer J Gastroenterol. 2009;104:739-750.

10. Whitlock EP, et al. Screening for colorectal cancer: a targeted updated systematic review for the U.S. Preventive Services Task Force. Ann Intern Med. 2008;149(9):638-658.

11. Jimbo M, et al. Effectiveness of complete diagnostic examination in clinical practice settings. Cancer Detect Prev. 2006;30(6):545-551.

12. Schoen RE. The case for population-based screening for colorectal cancer. Nat Rev Cancer. 2002;2(1):65-70.

13. Imperial TF, et al. Fecal DNA versus fecal occult blood for colorectal cancer screening in an average-risk population. N Engl J Med. 2004;351(26):2704-2714.

14. Nelson NJ. Virtual colonoscopy accepted as primary colon cancer screening test. J Natl Cancer Instit. 2008;100(21):1492-1499.

15. Halbert CH, et al. Colon cancer screening practices following genetic testing for hereditary nonpolypsis colon cancer (HNPCC) mutations. Arch Intern Med. 2004;164(17):1881-1887.

16. Boursi B, Arger N. Current and future strategies in colon cancer prevention and the emerging role of chemoprevention. Curr Pharm Des. 2007;13(22):2274-2282.

17. Colon cancer risk assessment tool. Available at: Accessed Aug. 27, 2009.

18. American Cancer Society. Detailed Guide: Colon and Rectum Cancer. Can Colorectal Polyps and Cancer be Found Early? Available at: Accessed Aug. 27, 2009.

Susan VanBeuge is a family nurse practitioner who is on faculty at the University of Nevada in Las Vegas. She practices part time in an endocrinology practice and is pursuing a doctorate in nursing practice at the University of Utah.


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