The colon is a tubular organ about 5 feet long and 3 inches in diameter.
Its purpose is to absorb the fluids that are used to digest our food and store the undigested portion of what we’ve eaten until it can be passed along. There is also increasing evidence that the bacterial environment present within it has a significant role in helping our immune systems.
Like most of our organs, it is subject to the development of diseases including cancer. In fact, colon cancer is the third most common cancer in this country and the third most common cause of cancer deaths.
It is expected to be the cause of over 50,000 deaths this year alone. This is a very unfortunate statistic as most colon cancers are preventable.
Colon cancers usually arise from the abnormal growth of a colon polyp. Factors that increase the risk for development of polyps include age, a high-fat diet, certain races, obesity, alcohol consumption, diabetes, smoking, and having a first-degree family member that has colon cancer.
However, everyone has some risk for the development of colon cancer. Fortunately, there are screening tests that can detect pre-cancerous polyps before they become cancerous. Current recommendations are for everyone between the ages of 50 and 75 to be screened for colon cancer while individuals with high-risk factors may be screened earlier than age 50. Individuals older than 75 may be screened if they are healthy enough to undergo treatment for a colon cancer if it is found.
Many polyps and most cancers will release small amounts of blood into the colon. When not visible in the stool a fecal occult blood test (FOBT) or fecal immunochemical test (FIT) can detect this blood.
These tests require an individual to obtain a specimen and submit it for processing. The older FOBT does require avoidance of red meat and certain medications such as aspirin to avoid a false positive test. These tests can detect up to 75% of colon cancers but only 10-20% of precancerous polyps.
If used as the only screening method, it should be done every year.
A more accurate means of screening for colon cancer is to directly visualize precancerous polyps.
In order to do this a scope needs to be introduced into the rectum and advanced into the colon. The colon must first be emptied with laxatives and/or enemas. The first scopes were rigid tubes about 2 feet long and an inch in diameter.
For obvious reasons these were very unpopular, especially since what could actually be seen was limited. With the development of glass fibers in the 1950s that could transmit light it was possible to make the scopes smaller and flexible.
Not only did this allow better visualization but was much more comfortable for the patient. The first scopes were still quite short and could only reach that portion of the colon called the sigmoid colon.
Hence the name “sigmoidoscope.” Sigmoidoscopy has the additional limitation of being unable to remove polyps if they are seen. If used for screening it should be done every 5 years along with a stool test every year.
As scope technology improved longer scopes capable of viewing the entire colon were developed. A colonoscopy can find over 75% of precancerous polyps and 95% of early cancers and is the most accurate test currently available. It is a simple outpatient procedure performed under sedation and should be done every 10 years.
Other tests such as virtual colonoscopy, swallowed cameras and cancer DNA tests have been developed but are not widely used. With proper screening colon cancer deaths can and should become rare.
The best recommendation is to discuss your risks and screening options with your health care provider.
- This series brought to you by Brian Bell, M.D., Lincoln County’s only board-certified OB/GYN and Chief of Staff at Cabinet Peaks Medical Center