Flat Colon Polyps and Endoscopic Mucosal Resection
G.S. Raju, MD., Department of Gastroenterology, MD Anderson Cancer
Center and Roy Soetikno, MD, Department of Gastroenterology, Palo Alto
VA Medical Center, Stanford Medical School, Palo Alto
Colon cancer is relatively common. Slightly more than 1 in 20 Americans will develop it during their lifetime. Unlike many other cancers, however, colon cancer is preventable.
Colonoscopy, the gold standard in colon cancer prevention, is a simple procedure compared to the emotional and physical turmoil that one would go through dealing with colon cancer. All that is required is taking the time off to prepare for and undergo the procedure.
Flat lesions are challenging
The precursor of colon cancer is called a polyp. Many polyps are easy to detect because they are shaped like a mushroom. The flat ones, however, are more deadly and can easily be missed during colonoscopy, especially when the colon is not clean. These subtle flat lesions also require a special technique, called endoscopic mucosal resection, to remove them safely and completely. Endoscopic mucosal resection is a very delicate colonoscopic technique. The flat lesion is first lifted from the colon by carefully injecting fluid into the colon wall underneath the lesion. The lesion is then carefully shaved off, along with superficial layers of colon, without damaging deeper layers.
Several issues are critical for complete and safe removal of flat lesions and for patients to enjoy the benefits of a non-invasive procedure, while avoiding the risks and costs of surgery.
Excellent colon preparation is essential: Without it, one may overlook flat lesions. In addition, once a large, flat lesion is seen, it should be removed by endoscopic mucosal resection.
Patient cooperation is critical: It is important to inject fluid accurately into a 2-3 mm colon wall to lift the lesion. This is technically challenging if the patient is deeply sedated and cannot hold his or her breath for a few seconds when the injection is made. To help with this, the procedure is done with light sedation when needed. Patients have no pain during the injection or removal of polyps.
Expertise and excellent team work: Several steps are involved during endoscopic mucosal resection; injection of fluid, lifting the lesion, cutting the lesion, cleaning the edges of any residual polyps, cauterizing any bleeding vessels, and closing the defect if necessary success depends on a number of factors, including careful instruction by the endoscopist and the endoscopic technician, anticipating steps and getting them right..
Excellent gastrointestinal pathologists are essential: Endoscopists should review the pathology specimens with the pathologists to figure out how best to follow the patients.
Close follow-up of patients: Close follow-up of the patients in the first two to three weeks is critical, because the resection site could cause delayed bleeding or perforation. Patients may be placed on a special diet to avoid loading up the colon with stool and disrupting the resection site.
Challenges with endoscopic mucosal resection
Although endoscopic mucosal resection helps patients avoid major colon surgery, it is not widely practiced for the following reasons:
This is a relatively new technique and not every endoscopist is able to offer this service because of lack of training in the delicate technique of submucosal injection and proper use of clips to close perforations if they were to occur.
Insurance companies are not aware that endoscopic mucosal resection can prevent and replace surgery. The reimbursement for endoscopic mucosal resection is similar to removing an easy polyp, while it takes three to four times longer to do a simple colonoscopy. This could be overcome by doing these procedures in specialized therapeutic colonoscopy centers and working out appropriate reimbursement.