Colon cancer is a leading cause of cancer death in the US, second only to lung cancer. Fortunately, there are effective tests that can diagnose colon cancer early, or even prevent colon cancer while it is still a pre-cancerous polyp. Given that this is one of the few cancers for which effective screening exists, I have been very enthusiastic about recommending colon cancer screening to all my patients over 50.
The options for screening thus far have been colonoscopy, sigmoidoscopy, fecal occult blood testing, and barium enema. Each of these tests has some benefits and drawbacks, and none have been directly compared to each other in any large studies. Of these tests, colonoscopy has become the standard of care in our community, largely because it examines the entire colon and allows for the removal of polyps during the examination.
This week, the American Cancer Society released new recommendations for colon cancer screening. This generated much coverage in the general media, including this NY Times article. The major change in these new recommendations is the addition of two new testing options for colon cancer screening: CT colonography (also called virtual colonoscopy), and a stool DNA test.
Though these new options may be helpful for the occasional patient that has specific problems that preclude conventional colonoscopy, I think for most patients the new options will not be helpful. First, there have still been no studies that directly compare the accuracy of any of these screening tests. Second, CT colonography while less invasive than colonoscopy, still involves the most uncomfortable part of colonoscopy: the preparation the night before that evacuates the colon. CT colonography also canâ€™t remove any polyps. So if any polyps are detected with CT colonography, a conventional colonoscopy is then needed to remove the polyp. Finally, the stool DNA test is too new and impractical. It is difficult to administer (donâ€™t ask) and its accuracy is not yet well understood.
Many of my patients are squeamish and quite reluctant when I recommend colonoscopy for colon cancer screening. After the test almost all of them tell me it wasnâ€™t nearly as bad as they feared. I try to reassure my patients by promising them that on my fiftieth birthday Iâ€™ll get a colonoscopy too. That promise still stands despite the new recommendations.