Did You Know You Might Have 2 Colons?

By Dr. Jeff Axler, Director, Gastroenterology and Endoscopy Clinic

Just when you thought you heard everything about your body, some people would have us believe we have 2 colons. To be more specific, some believe the right colon and the left colon are different.  We used to think that the colon was just one long tube that started at the upper intestine and continued all the way to the rectum.  Of course there is only one colon (large intestine), but there is some evidence that the right side of the colon acts differently from the left side of the colon, thus creating the 2 colon effect.

So why is that? The right colon is wider, so it is less likely to become blocked. On the other hand, right-sided colon cancers can grow slowly without causing a blockage, and can bleed very slowly.  So slowly that you might not notice the small amount of blood in the stool.  Thus, it is more common for right-sided colon cancers to present as anemia (low blood count) from blood loss, and left-sided cancers to present with a bowel obstruction.

In the past 20 years, screening for colon cancer has become routine worldwide, and colonoscopy has been the gold standard for detecting colon cancers.   

So, do the right and left side act differently in screening studies?

Some reports suggested that screening colonoscopy do not prevent colon cancers on the right side. It came as a surprise that the right colon was not being protected by having a colonoscopy and experts wondered how could this be.  It was suspected that some doctors were just not going far enough inside to view the entire colon. Incomplete tests would naturally make missing a cancer more likely.  The quality of the preparation also seemed important. Those patients with poor colonic preparations seemed to have higher cancer “miss” rates.  Another factor was the training of the endoscopist, i.e. the type of doctor also seemed important. The cancer "miss" rate was highest with general doctors or surgeons.  The best results were with patients who had their tests done by specially trained gastroenterologists. The final suggestion was that perhaps the right colon acts differently, and that the cells lining the right colon might have a higher chance of developing colon cancer.  Those cells may form malignant polyps more quickly.

But truly there is only one colon. Newly published reports from Ontario and Germany show report that there is protection from colon cancer by having a colonoscopy and that the right side of the colon can be protected as well as the left side.

There were some interesting items noted in these newer studies. Patients with higher levels of education had lower rates of colon cancer.  Meanwhile, smokers and those with family histories of colon cancer had higher rates of cancer. Having a colonoscopy was strongly associated with reducing the rate of colon cancer in all parts of the colon, for both men and women, and in all age groups.  This risk reduction seemed to relate to removal of polyps that might have become cancer years later.  To summarize: your best chance of reducing colon cancer on both sides of your colon happens when you have a high quality colonoscopy (with a good prep), done by a top qualified gastroenterologists, who will find and remove any polyps. 

And by the way...that’s what you get when you have your test at Medcan.  We only have highly trained gastroenterologists, using state-of-the-art equipment, in our brand new designed endoscopy area.  We will check your right colon and your left colon, and make the connection!