The Flat Polyp - Should I Be Worried?
Published March 20, 2008
March is colon cancer awareness month, and there are several exciting and new developments that can help detect and prevent this deadly disease. In the United States, colon cancer is the third most common cancer, and the second deadliest cancer killer. It is an equal opportunity killer, affecting both men and women equally, with women and African Americans having a slightly higher mortality. Colon cancer is currently responsible for more deaths than breast cancer or prostate cancer! Recently, a new study was published in the Journal of the American Medical Association which found that the significance of an easily overlooked lesion in the colon - the so called flat polyp - was more serious than previously thought.
Samuel Bae, Gastroenterologist and Chairman of Internal Medicine at Hunterdon Medical Center explained,"after lung cancer, colon cancer is the second leading cause of cancer death in the United States. We estimate that about 154,000 new cases will be detected in the US this year, with over 50,000 deaths. That being said, the good news is that colon cancer is also one of the most preventable and potentially curable cancers if found early. We have a very good understanding of the natural history of colon cancer, and know that the vast majority of colon cancers arise from precancerous colon polyps. With this knowledge, doctors, namely gastroenterologists, feel confident that as these colon polyps are removed, the natural cycle of cancer development is interrupted, and that polyp is literally prevented from maturing into a cancer." Dr. Bae elaborated, "this is the great irony of this disease - such a deadly cancer, but also one of the most easily preventable if caught early enough. Often times, early curable lesions are asymptomatic - that is - you feel great. When I see a patient in my office for a possible screening evaluation, a common question I get is 'Doc, do I really need to do anything - I feel too good.' My answer is 'It's because you feel so well that you should consider screening!'"
Colonoscopy is considered the gold standard in screening for colon cancer. Essentially, a flexible, controllable camera-tipped scope is used to examine all parts of the colon lining. Not only is it the best diagnostic tool available, but it is also therapeutic. If a growth or abnormality is found on examination, the doctor can usually remove or deal with the problem at the time of the exam. When it comes to precancerous polyps, that removal usually means "cure" from any potential cancer that polyp may have represented. It is this one-two punch of excellent diagnostics and therapeutic potential that has made colonoscopy such an effective tool.
Classically, polyps have been described as lesions or abnormalities which protrude or "jut out" of the wall of the colon. The new study by Dr. Roy Soetikno of the Veterans Affairs Palo Alto Health Care System challenges this assumption. He found that in studying over 1,800 veterans who underwent colonoscopy, almost 10 percent had flat lesions. More ominously, these flat lesions were about 5 times more likely than typical polyps to have cancerous or precancerous tissue! While these flat or depressed lesions accounted for only 15 percent of potentially cancerous growths, they accounted for almost half of all cancers. Now, gastroenterologists have known about these flat lesions for decades. However, they were mostly described in international studies - especially from Japan in the 1980's and 1990's, and there was some controversy whether these lesions had any significance in the United States. This study shows that these flat lesions are not just a foreign phenomena, but can have serious implications here in the United States. Flat lesions can be more difficult to detect, and are more apt to be missed if the exam is not thorough or if the preparation is sub-optimal. If there is a suspicion that there may be a flat lesion, a special technique called chromoendoscopy can help locate and delineate the margins of any potential abnormality. A special dye injected through the scope using a special catheter, creates a bas relief effect. This is a technique that, while not common, can be easily taught to the majority of practicing doctors.
This study is also very timely. Currently, there is greater scrutiny about the overall quality of performing colonoscopy. A recent study found that depending on how thoroughly a doctor performs a colonoscopy can translate into how effective he or she is in finding colon lesions. Some doctors were 10 times more likely than their associates in finding these precancerous lesions! This may help explain why up to 1% of colon cancers occur in patients who have recently had a colonoscopy and polyp removal.
Does this mean that you need to rush out and get another colonoscopy? For most people, no. Most gastroenterologists are well trained and proficient in their craft. However, the finding that these flat polyps do exist and can be potentially more dangerous than standard polyps should motivate doctors doing colonoscopy to be thorough and careful with every procedure they do. Likewise, it would benefit patients to comply with the preparation instructions to ensure an adequate bowel cleansing. These subtle lesions can be easily missed if there is any retained material within the colon. The findings of this new study just adds to the overall knowledge base that can make this deadly disease eminently preventable.
Samuel Bae, M.D. is a Gastronenterologist at Hunterdon Medical Center. His areas of interest lie in cancer prevention and therapy, and he is actively involved at the Hunterdon Regional Cancer Center. Dr. Bae is a graduate from Memorial Sloan Kettering Cancer Center, and currently the Chairman of Internal Medicine at Hunterdon Medical Center.