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Screening and Surveillance for Colorectal Cancer

Screening and Surveillance for Colorectal Cancer | ASCRS


Colorectal cancer is the fourth most common non-skin cancer, affecting all ethnic groups. 140,000 people will be diagnosed with colorectal cancer each year and more than 50,000 will die; the lifetime risk is 1 in 20 (5%).  An increased risk of developing colorectal cancer is present if there is a personal or family history of colorectal cancer.  A personal history of breast, uterine, or ovarian cancer also increases one’s risk of developing colorectal cancer.  A personal or family history of colonic polyps also increases that risk. Both Crohn’s Disease and ulcerative colitis may also make colorectal cancer more likely after having the disease for a number of years.


Colorectal cancer rarely causes symptoms in its early stages. Colon cancer usually starts out as a benign polyp. Colon polyps can be both pre-cancerous and non-pre-cancerous.  Polyps can be detected by screening tests and can be removed, thus preventing colorectal cancer. Early cancers can be cured in up to 90% of cases. Once colorectal cancer causes bleeding, change in bowel habits, or abdominal pain, it has usually progressed to a more advanced stage where less than 50% of patients are cured.


Fecal occult blood testing checks several stool samples for invisible amounts of blood from a colorectal polyp or cancer. If it is positive, a colonoscopy (see below) is needed.

Colonoscopy uses a long, flexible instrument to evaluate the lining of the colon and rectum; abnormal areas may be sampled or removed and sent to the lab for testing. Safe and effective, colonoscopy is the most commonly recommended screening test, as the whole colon is seen and pre-cancerous polyps can be removed, preventing colon cancer.  Colonoscopy is the “gold standard” for colorectal cancer screening.

Flexible sigmoidoscopy allows a physician to look at the lower third of the colon, where about half of all polyps and cancers are found. If an abnormality is found, a colonoscopy is then needed. Fecal occult blood testing and flexible sigmoidoscopy are often combined for colorectal cancer screening.  However, colonoscopy, is considered the optimal method of screening when the test is available and there is no medical contraindication.

An air-contrast barium enema is an x-ray test in which the colon is filled with air and dye to make the lining visible. It is mostly used only if a complete colonoscopy cannot be done.

Virtual colonoscopy combines CT scan images of the air-filled colon into pictures that look like a colonoscopy.  If abnormalities are found, colonoscopy is then necessary. It is also useful in patients who have an incomplete colonoscopy.  However, most insurance plans as well as Medicare may not cover this procedure.


For people with no risk factors, screening starts at age 45.* Having a colonoscopy every 10 years is considered the gold standard. Flexible sigmoidoscopy every 5 years with yearly stool occult blood testing is an acceptable alternative when a colonoscopy is not feasible.

People with a close relative (parent or sibling) with colorectal cancer or polyps will start screening at age 40, or 10 years before the youngest age at which a relative was diagnosed. These patients will often undergo screening every 5 years, even if their test is normal.

Less common types of inherited colon cancer (hereditary non-polyposis colon cancer and familial adenomatous polyposis) may require much more frequent screening, beginning at a much earlier age. 

*In 2018, secondary to new data on the increased risks of colon cancer in those under 50, the American Society of Colon and Rectal Surgery changed recommendations to consider starting screening at age 45. 


People who have precancerous polyps completely removed should have a colonoscopy every 3 to 5 years, depending on the size, type and number of polyps found. The exam interval will usually depend upon the pathology of the growth removed.  If a polyp is not completely removed by colonoscopy or surgery, another colonoscopy should be done in 3 to 6 months.

Most colorectal cancer patients should have a colonoscopy within 1 year of its initial removal. If the whole colon could not be examined prior to surgery, then colonoscopy should be done within 3 to 6 months. If this first surveillance is normal, then colonoscopy should be done every 3 to 5 years.

Patients with ulcerative colitis or Crohn’s Disease for 8 or more years should have a colonoscopy with multiple biopsies every 1 to 2 years.


Colon and rectal surgeons are experts in the surgical and non-surgical treatment of diseases of the colon, rectum, and anus. They have completed advanced surgical training in the treatment of these diseases, as well as full general surgical training. They are well versed in the treatment of both benign and malignant diseases of the colon, rectum and anus and are able to perform routine screening examinations and surgically treat conditions, if indicated to do so.


The American Society of Colon and Rectal Surgeons is dedicated to ensuring high-quality patient care by advancing the science, prevention and management of disorders and diseases of the colon, rectum and anus. These brochures are inclusive but not prescriptive. Their purpose is to provide information on diseases and processes, rather than dictate a specific form of treatment. They are intended for the use of all practitioners, health care workers and patients who desire information about the management of the conditions addressed. It should be recognized that these brochures should not be deemed inclusive of all proper methods of care or exclusive of methods of care reasonably directed to obtain the same results. The ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of all the circumstances presented by the individual patient.