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Quick Facts
- Regular screening can, in many cases, prevent colorectal cancer
- Screening for adults aged 50-75 years has increased from 52% in 2002 to 63% in 2008
- The overall lifetime risk of developing CRC is 1 in 20 and is slightly higher in women than in men
Colorectal Cancer Screening

Colorectal cancer (CRC) is preventable by removing pre-cancerous lesions or adenomatous polyps long before invasive cancer develops. For men and women at average risk for developing CRC, screening is advised starting at age 50.  In this population, it is estimated that the risk of developing a colorectal adenoma is approximately 19% and that 2-5% of sporadic polyps will develop into an invasive carcinoma (Labianca, 2005). An adenoma is considered a polyp that can transform into cancer and is therefore considered a pre-cancerous lesion. In general, hyperplastic and inflammatory polyps are not considered pre-cancerous’ however, may be a sign of being at greater risk for developing an adenoma (ACS, 2011).

Five to 15% of individuals have a genetic predisposition for development of CRC, thus cancer can develop in these patients at an earlier age.  The two most common inherited syndromes are familial adenomatous polyposis syndrome (FAP) and hereditary non-polyposis colon cancer (HNPCC) or Lynch syndrome. HNPCC accounts for 3 to 5% of all colorectal cancers and FAP accounts for 1% of cancers of the colon and rectum. Given that the risk of CRC can vary among individuals, based on average, increased or high risk factors, recommendations for CRC screening are made accordingly. 

Table 1. Stratification of CRC Risk Groups

Risk Rating

Risk Criteria

Average  Risk

  • Age = 50
  • No personal history of adenoma, CRC or inflammatory bowel disease
  • Negative family history

Increased Risk

  • Personal history of adenomas/sessile serrated polyps, CRC or inflammatory bowel disease
  • Positive family history of CRC or advanced adenomas

High Risk

  • Family history of HNPCC or Lynch syndrome
  • Personal or family history of: FAP, MYH-Associated Polyposis (MAP-1), Peutz-Jeghers Syndrome (PJS-1), Juvenile Polyposis Syndrome (JPS-1), Hyperplastic Polyposis Syndrome (HPP-1)

Based on information from the National Comprehensive Cancer Network (2011) and the American Cancer Society (2011).

Effective, safe methods for screening are available and embraced by a variety of reputable organizations including the National Comprehensive Cancer Network (NCCN, 2011) and the American Cancer Society (ACS, 2011). Screening is one of the most powerful tools for preventing CRC. It can take 10 to 15 year from the initiation of abnormal cell growth into polyps, for CRC to develop. Thus regular screening can, in many cases, prevent CRC. Screening for adults aged 50-75 years has increased from 52% in 2002 to 63% in 2008 (Richardson, 2010). The increase in screening may contribute to the declining incidence of CRC which has accelerated from 1998 through 2007. The overall lifetime risk of developing CRC is 1 in 20 and is slightly higher in women than in men (ACS, 2011). 

There are several options for CRC screening:

  1. Fecal Occult Blood Testing (FOBT) detects blood loss in the stool. This test is performed on a fecal sample which has been placed on a guaiac-impregnated card. Through addition of a hydrogen peroxide developer, a positive test is reflected in the appearance of a blue color. This test should be performed on 3 separate bowel movements. Dietary substances like rare red meat, turnips or horseradish can result in a false positive or vitamin C can result in a false negative.  Restrictions of these substances have not been shown to reduce this false positivity rate rather they may inhibit compliance with the testing (Pignone, 2001). Additionally, it is recommended that non-steroidal anti-inflammatory drugs be avoided 7 days prior to testing as they can cause bleeding which can result in a false positive.
  2. Fecal Immunohistochemical Test (FIT) was approved by the Food and Drug administration (FDA) in 2001. It can detect hidden blood in the stool. It reacts to part of the human hemoglobin protein found in red blood cells. No dietary restrictions are required prior to this test and it only requires one specimen (NCCN, 2011).
  3. Stool DNA Test looks for certain abnormal sections of DNA. For this test an entire bowel movement is collected and examined in the lab for cancer cells. Frequency of testing for stool DNA is not yet known (ACS, 2011).
  4. Sigmoidoscopy is an invasive procedure using a 60 cm flexible lighted tube inserted into the rectum and can visualize the lower part of the colon. A video camera is at the end of the scope and images are visualized on a display monitor. Polyps can be biopsied and removed through the scope. This procedure can be done without sedation.  The greatest limitation of this procedure is that it can identify premalignant and malignant lesions in only half of the colon. Abnormal findings will result in the patient needing to undergo a colonoscopy (ACS, 2011).
  5. Colonoscopy is an invasive procedure through which the entire length of the colon is visualized through a colonoscope. Similar to the sigmoidoscope, it has a video camera on the end which allows the endoscopist to closely view the colon on a display screen. Biopsy and removal of suspicious findings can be done during the procedure. Patients typically receive anesthesia for this procedure (ACS, 2011).
  6. Double-Contrast Barium Enema (DCBE) or lower gastrointestinal series. This procedure done in the radiology department entails the insertion of a small flexible tube into the rectum through which barium is injected. Air is injected following the barium to assist in expansion. DCBE is insensitive to detecting small or flat adenomas and is only recommended when a total colonoscopy cannot be completed (Labianca, 2001).
  7. Computerized Tomography (CT) Colonoscopy or virtual colonoscopy uses 3-dimensional imaging. During this test the patient will lie on a table and a small flexible tube is inserted into the rectum through which air is pumped in to expand the colon for better visualization. Positive findings on this test will require follow-up with a colonoscopy (ACS, 2011).

Screening tools fall into two categories: structural tests and fecal-based tests. Tests that can detect early cancer and adenomatous polyps should be encouraged.

Table 2. Screening Guidelines for Individuals with Average CRC Risk



Testing Method


Tests that find polyps and cancer

Flexible sigmoidoscopy*


Colonoscopy or


CT Colonoscopy*

Every 5 years starting
at age 50

Every 10 years, starting at age 50

Every 5 years, starting at age 50

Tests that mainly find cancer

Fecal occult blood test (FOBT) with at least 50% test sensitivity for cancer,

Fecal immunochemical test (FIT) with at least 50% test sensitivity for cancer *


Stool DNA test (sDNA)*


Annually, starting
at age 50



Annually, starting at
age 50



Interval uncertain, start at age 50

Based on information from NCCN (2011) and ACS (2011).                                                                                                                                                                
Double-contrast barium enema every 5 years may be recommended if other modalities not available. 
*If positive, colonoscopy should be performed.                                                                                                 
‡FOBT and FIT performed with a digital rectal exam is not adequate for screening.                                                                                                       

For those individuals with intermediate risk (IR) or high risk (HR) of developing CRC, screening recommendations are adjusted in terms of method and frequency. The individualized plan for screening can also be adjusted dependent on the number of risk factors.

Table 3. Colonoscopy Screening Guidelines for Intermediate and High Risk Individuals

Risk Factor

Grade of Risk

American Cancer Society (ACS)

National Comprehensive Cancer Network (NCCN)

History of Low Risk Adenoma


5-10 years after polyps removed

Repeat at 5 years then every 5-10 years if normal

History of High Risk Adenoma


Within 3 years after removal of 3-10 or >10 adenomas or a single adenoma > 1 cm

2-6 months after removal of sessile adenomas (if removed in pieces)

Repeat in 3 years then in 5 years depending on findings

Inflammatory Bowel Disease



Cancer risk increases 8 years after onset of pancolitis and 10-12 years after left-sided colitis. Colonoscopy  every 1-2 years with biopsies for dysplasia

Initiate colonoscopy 8-10 years after onset of symptoms and repeat every 1-2 years

Personal History CRC


Within 1 year following colon resection, if normal repeat in 3 years. If normal then repeat every 5 years.

1 year post-surgery, if normal then repeat in 2-3 years, if positive for adenoma or sessile serrated polyp repeat 1-3 years

First Degree Relative (FDR) History of CRC


Start at age 40 or 10 years less than a FDR diagnosed < age 60 or in 2 FDR at any age, repeat every 5 years



Start at age 40, for FDR diagnosed at age >60 or 2 FDR diagnosed at any age. Screening options are the same as those at average risk

Start at age 40 or 10 years less than the earliest diagnosis of FDR, if FDR diagnosed at age = 50 or 2 FDR diagnosed at any age screening interval should be between 3-5 years.


Start at age 40, if FDR diagnosed between ages 50-60. Repeat every 5 years.


Start at age 50, if FDR diagnosed at age = 60 Repeat every 5 years.


Family History of Familial Adenomatous Polyposis Syndrome (FAP)


Start at age 10-12 years with flexible sigmoidoscopy; counseling to consider genetic testing

Starting at age 10-15 with flexible sigmoidoscopy or colonoscopy, yearly.

Then every 2 years until age 24 and every 3 years until age 44 then every 3-5 years.

Genetic testing is recommended.


Hereditary Non-Polyposis Syndrome (HNPCC) or Lynch Syndrome.


Start at age 20-25 or 10 years before the youngest case in the immediate family.

Consider genetic testing

Start at age 20-25 or 2-5 years younger than the youngest case in the immediate family, whichever comes first. Repeat every 1-2 years. Consider genetic testing

Based on information from NCCN (2011) and ACS (2011).
IR = Intermediate Risk, HR = High Risk.                            

American Cancer Society. Colorectal cancer: early detection. Retrieved from http://www.cancer.org/docroot/CRI/content/CRI_2_6X_Colorectal_Cancer_Early_Detection_10.asp?sitearea=&level

Labianca, R., Beretta, G. D., Mosconi, S., Milesi, L., & Pessi, M. A. (2005). Colorectal cancer: screening. Annals of Oncology, 16 (Supplement 2): ii127-ii132. doi:10.1093/annonc/mdi730  Link to free full text http://annonc.oxfordjournals.org/content/16/suppl_2/ii127.full.pdf+html

National Comprehensive Cancer Network. (2011). Colorectal cancer screening. NCCN Clinical Practice Guidelines in Oncology. Version 2.2011. Retrieved from http://www.nccn.org/professionals/physician_gls/pdf/colorectal_screening.pdf

Pignone, M., Campbell, M. K., Carr, C., & Phillips, C. (2001). Meta-analysis of dietary restriction during fecal occult blood testing. Effective Clinical Practice, 4: 150-156. Link to free full text http://www.acponline.org/clinical_information/journals_publications/ecp/julaug01/pignone.htm

Richardson, L.C., Rim, S.H., & Plescia, M. (2010). Vital signs: Colorectal cancer screening among adults aged 50-75 years - United States, 2008. Morbidity and Mortality Weekly Report (Centers for Disease Control and Prevention), 59: 808-812. Retrieved from http://www.cdc.gov/mmwr/

Article Created On : 4/22/2009 5:34:30 PM             Article Updated On : 10/26/2011 12:29:00 PM