Colorectal Cancer Awareness and Screening
Gregory Austin, MD, MPH
Assistant Professor of Medicine, University of Colorado, Denver
University of Colorado Hospital Gastroenterology Service
Colorectal Cancer (CRC) is the 2nd leading cause of cancer-related
death overall and affects men and women equally. The American
Cancer Society estimates that there were over 70,000 cases of CRC
and about 25,000 deaths from CRC among women in 2010. More
than 90% of colorectal cancers in both men and women are
diagnosed after the age of 50, and the risk increases with age. A
variety of factors have been identified that increase an individual’s
risk for developing CRC. These include smoking, excessive alcohol
intake, a personal history of inflammatory bowel disease, obesity,
and diabetes. Some protective factors have been identified,
including physical activity, a high-fruit/high-vegetable diet, and daily
use of aspirin. Fortunately, CRC is one of the few cancers for which
effective screening strategies exist. Primarily because of screening, CRC mortality has
been progressively declining since 1990, at a rate of about 3 percent per year.
Screening for CRC is important as patients can have
cancer but not have any symptoms. The earlier a
cancer can be detected and treated, the better the
prognosis for the patient. If CRC is found and treated
at the earliest stage (before it has spread), 5-year
survival approaches 90%. However, screening rates
for CRC lag behind those of other effective screening
tests (such as mammography), so that only about
40% of cases are diagnosed in the earliest stage.
Furthermore, screening with flexible sigmoidoscopy or colonoscopy allows precancerous
polyps (adenomas) to be detected and removed, thereby preventing patients from ever
developing CRC. Symptoms that should raise the suspicion for CRC include (but are not
limited to) rectal bleeding, fatigue, weight loss, a change in bowel habits (such as a
decrease in stool caliber and frequency), or abdominal pain. If these symptoms are
present, patients should discuss them with their physician to determine whether further
evaluation is warranted.
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Because patients frequently do not have symptoms of CRC until the cancer has advanced or
spread, all major organizations recommend average-risk patients undergo screening for
CRC starting at the age of 50. An average-risk patient is one who does not have any firstdegree relatives (parents, siblings, and children) who have been diagnosed with CRC and
does not have a personal history of precancerous polyps or CRC. Approximately 75% of
CRC cases occur in patients who do not have a family history of CRC, with the other 25%
occurring in patients with a family history. Patients who have one or more first-degree
relatives with a history of CRC are at increased risk for CRC at an earlier age.
Consequently, guidelines recommend these patients begin screening at the age of 40 (or 10
years younger than the earliest cancer in the family). If a patient has more than one firstdegree relative with CRC or there is a history of CRC in multiple generations, patients
should discuss with their physician at what age they should begin screening.
Many organizations, including the American
Gastroenterological Association and the American College of
Gynecology, endorse colonoscopy as the preferred method
for CRC screening. However, the method of screening will
depend on an individual patient’s preferences and risk
factors. For those at average-risk, the recommendations
allow for a wide array of screening options. These include
stool-based tests, such as fecal occult blood testing. These
stool-based tests are primarily designed to detect cancers.
However, because they have a lower sensitivity for detecting cancer compared to other
screening modalities, guidelines recommend stool testing for occult blood should be
performed yearly.
Screening for CRC can also be performed radiographically, with either double-contrast
barium enema or more recently with computerized tomographic colonography (CTC,
sometimes called virtual colonoscopy). Barium enema is moderately sensitive for detecting
large polyps and cancers and can be performed every five years. Many recommendations
suggest combining barium enema every five years with annual stool testing for occult blood.
CTC is a relatively new screening method for colorectal cancer screening. It has good
sensitivity and specificity for detecting large polyps and cancers. However, it is not widely
available at this time, and is not currently covered by Medicare.
The final option for CRC screening involves an endoscopic evaluation, with either flexible
sigmoidoscopy (which evaluates the last third of the colon, including the rectum) or
colonoscopy (which evaluates the entire colon and rectum). These procedures allow for
direct visualization of the lining of the colon and rectum. Cancers can be detected and
biopsied, and precancerous polyps can be detected and removed. For average-risk
individuals who are screened with any method other than colonoscopy, an abnormal test
result will require a subsequent colonoscopy. For individuals at high-risk for colon cancer,
either because of a family history of CRC or because of a personal history of adenomatous
polyps, colonoscopy is the preferred screening test. Because a colonoscopy can detect and
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remove precancerous polyps, it is estimated that colonoscopy can decrease the chances of
developing CRC by 70-90%.
Colon Video Capsule Endoscopy
Many of our patients inquire about video capsule colonoscopy and many times strongly
request it. Colon video capsule endoscopy is in trials in Europe but its role is still uncertain.
Like optical colonoscopy, a colon preparation is necessary prior to the examination.
Additional medications are given during the procedure to increase transit of the capsule.
Colonic capsule endoscopy does not allow for the biopsy or polyp removal, so patients with
lesions detected during the examination typically require subsequent colonoscopy for further
evaluation and/or treatment. Studies looking at the efficiency of colon capsule endoscopy
compared to standard colonoscopy have reached variable results. Video capsule endoscopy
is most commonly used for evaluation of small bowel but not yet approved by the FDA for
colon cancer screening.
Summary
CRC is common in both men and women. The majority of CRC’s occur in patients without a
family history of CRC, such that all average-risk individuals should begin CRC screening at
age 50. If there is a family history of CRC, screening should begin earlier and colonoscopy
is the preferred test of choice in these high-risk patients.
For more information on colorectal cancer and screening options:
American Gastroenterological Association: www.gastro.org/patient-center
American Cancer Society: www.cancer.org/Cancer/ColonandRectumCancer
About the Doctor
Gregory L. Austin, MD, MPH,
University of Colorado Hospital
Assistant Professor, Gastroenterology and Hepatology
University Of Colorado Denver
Dr. Austin received his M.D. and M.P.H. from Yale University and
continued his training by completing a residency in internal
medicine at the Oregon Health and Science University. He completed his fellowship in
Gastroenterology and Hepatology at the University of North Carolina at Chapel Hill, and he
is board certified in internal medicine and gastroenterology. He actively pursues research in
nutrition and obesity, with a specific interest in the effect that low-carbohydrate diets have
on the gastrointestinal tract. Because of his public health background, Dr. Austin also has a
research interest in colorectal cancer screening and risk factors for colorectal cancer.
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For more information about The Services for Colorectal Screening and the Gastroenterology team
at the University of Colorado Hospital visit our website at
http://www.uch.edu/conditions/digestive-liver-pancreas/get-care.aspx
Call 720-848-2777 to Schedule an appointment
The Digestive Health Center at University of Colorado Hospital provides:
•
Coordinated GI clinic and endoscopy lab provides patients with expert care via clinic
consults for conditions such as Irritable Bowel Disease, Crohn’s, and other
gastrointestinal concerns and endoscopy lab for expert colorectal screenings and other
non-surgical procedures for symptomatic patients.
•
Premier regional referral center for GI cancer diagnosis and staging, and endoscopic
therapy with access to the latest endoscopic imaging techniques and virtual
microscopy, including multi-disciplinary and team approach with the Anschutz Cancer
Center.
•
State-of-the-art research facilities provide nationally known researchers with new skills
in developmental endoscopy, innovative techniques and assessing patient outcomes.
•
Nationally recognized experts in endoscopy treatment of the liver and pancreatic duct
diseases and non-surgical removal of gastrointestinal cancers.
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