Colon cancer screening saves lives!
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Colon cancer is important for everyone to consider.
Colon cancer affects about 5% of all people, men and women equally. When to start screening and which screening test to choose depends on if you are at average or higher risk of colon cancer
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Colon cancer affects 5% of our population
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Average risk means that you have no family history of colon cancer and no underlying chronic gastrointestinal illness that can increase your risk such is inflammatory bowel disease
An average risk person should begin colon cancer screening at age 50. |
What are my options for colon cancer screening?
The main options include: indirect stool tests for blood (FOBT AND FIT) and direct tests such as endoscopy (sigmoidoscopy or colonoscopy) or a CT scan (CT colonography or virtual colonoscopy). New stool tests for cancer DNA are available as well.
Let's look at the pros and cons of each test
Let's look at the pros and cons of each test
Stool tests
Test |
Advantages |
Disadvantages |
Accuracy |
Screening interval |
Fecal Occult Blood Test (FOBT) |
No cleansing of the colon is necessary. Samples can be collected at home. The cost is low compared with other colorectal cancer screening tests. No risks. |
This test fails to detect most polyps and some cancers May produce false-positive test results (the test suggests an abnormality when none is present) Dietary restrictions and changes, are often recommended for several days before a FOBT Colonoscopy will be required if abnormal |
Detection rate varies from 9-64% |
Recommended annually |
Fecal Immunochemical Test (FIT) |
No risk. No bowel preparation No pre-test dietary restrictions Sampling performed at home Fairly inexpensive |
May miss many polyps and some cancers May produce false-positive test results (the test suggests an abnormality when none is present) Should be performed annually according to guidelines Colonoscopy will be required if abnormal |
Detection rate is up to 65% |
Recommended annually |
Direct tests
Test |
Advantages |
Disadvantages |
Accuracy |
Screening interval |
Colonoscopy |
This test allows the doctor to view the entire colon. The doctor can perform a biopsy and remove polyps or other abnormal tissue during the test, if necessary. Other diseases can be detected at the same time |
Thorough cleansing of the colon is necessary before the test. This is an invasive procedure, so there is a risk of bleeding or tearing/perforation of the lining of the colon. |
Greater than 95% accurate in diagnosing colorectal cancer Accuracy depends on the experience of the person doing the exam This is considered by many experts to be the gold standard test |
Recommended every ten years |
Virtual Colonoscopy |
This test allows the doctor to view the entire colon. This is not an invasive procedure, so there is no risk of bleeding or tearing/perforation of the lining of the colon. |
This test may not detect all small polyps, non-polypoid lesions, and cancers, especially 5 mm or smaller. Thorough cleansing of the colon is necessary before the test. Radiation exposure If a polyp or non-polypoid lesion 6 mm in size or larger is detected, standard colonoscopy will be needed to remove it |
Up to 94% detection rate for large polyps, Accuracy depends on the experience of the person reviewing the exam |
Recommended every 5 years |
Stool test for cancer DNA
Test |
Advantages |
Disadvantages |
Accuracy |
Screening interval |
Stool DNA Test |
No direct risk to the colon No bowel preparation No pre-test dietary restrictions Sampling done at home |
May miss many polyps and some cancers May produce false-positive test results More expensive than other stool tests Still a fairly new test Not clear how often it should be performed Colonoscopy will be required if abnormal |
Detection rate is 72-77% |
Undetermined |
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There is sometimes just too much information. Here is my simplified version.
A colonoscopy is still the best to find and remove polyps, but the quality of the exam depends on both you and the doctor. If doing an invasive test does not worry you then do a colonoscopy. I reserve the virtual colonoscopy for patients who have difficult anatomy that makes it hard to do a colonoscopy or for a patient who is worried about the risk of a colonoscopy. Radiation exposure is a concern. The only stool test I recommend is the FIT and I feel it should be done yearly. Increasingly, the FIT will become the first screening test offered because of its low cost. At this time, the stool DNA tests have not shown sufficient accuracy to be recommended |
So what puts me at higher risk for colon cancer?
The main criteria is your family history. Other factors include a personal history of ulcerative or Crohn's colitis and certain genetic syndromes.
If you have a first degree relative with colon cancer than you are not at average risk only
A first degree relative is: father, mother, brother, sister, son or daughter
If you have a first degree relative with colon cancer than you are not at average risk only
A first degree relative is: father, mother, brother, sister, son or daughter
Colorectal cancer or adenomatous polyps in any first-degree relative before age 60, or in 2 or more first-degree relatives at any age (if not a hereditary syndrome).Start at age 40, or 10 years before the youngest case in the immediate family, whichever is earlier You should always do a colonoscopy since there is a higher chance of finding polyps. The colonoscopy should be repeated every 5 years |
Colorectal cancer or adenomatous polyps in any first-degree relative aged 60 or older, or in at least 2 second-degree relatives at any ageStart at age 40 You can do any of the option as those at average risk but most doctors would still recommend a colonoscopy |