{"id":36839,"date":"2011-07-03T15:44:49","date_gmt":"2011-07-03T15:44:49","guid":{"rendered":"http:\/\/euvolution.com\/futurist-transhuman-news-blog\/virtual-colonoscopy-can-be-hazardous-to-your-health\/"},"modified":"2011-07-03T15:44:49","modified_gmt":"2011-07-03T15:44:49","slug":"virtual-colonoscopy-can-be-hazardous-to-your-health","status":"publish","type":"post","link":"https:\/\/www.euvolution.com\/futurist-transhuman-news-blog\/medicine\/virtual-colonoscopy-can-be-hazardous-to-your-health.php","title":{"rendered":"Virtual Colonoscopy Can Be Hazardous to Your Health"},"content":{"rendered":"<p>The US Preventive Services Task Force (USPSTF) recommends that everyone aged 50-75 be screened for colon cancer with any one of three options: colonoscopy every 10 years, flexible sigmoidoscopy every 5 years, or fecal occult blood testing (FOBT) every year. Conventional colonoscopy is considered the &ldquo;gold standard&rdquo; since it allows for direct detection and biopsy of early cancers and removal of precancerous polyps. It involves passing a long colonoscope via the rectum through the full length of the colon and is also known as optical or visual colonoscopy. A newer and less invasive alternative, virtual colonoscopy or CT colonography, is being <a href=\"http:\/\/www.asconews.org\/anf\/Features\/Current+Controversies+in+Oncology\/The+Controversy:+CT+Colonography+for+Colorectal+Cancer+Screening+vs.+Optical+Colonoscopy\">promoted by some as the test of choice. Others disagree<\/a>.&nbsp;One area of controversy is that CTs frequently find &ldquo;incidentalomas&rdquo; that require further investigation. <a href=\"http:\/\/radiology.rsna.org\/content\/224\/3\/927.full\">An article in the journal <em>Radiology<\/em> highlights this problem<\/a>, describing &ldquo;the clinical drama that follows screening or diagnostic tests.&rdquo;<span><\/span><\/p><p>Virtual colonoscopy, or CT colonography, has some advantages:<\/p><ul><li>No sedation required.<\/li><li>Avoids the discomfort and the small risk of bowel perforation that accompany colonoscope insertion.<\/li><li>Takes less time.<\/li><li>Visualizes right colon (not well visualized in 10% of optical colonoscopies).<\/li><li>It is as effective as optical colonoscopy in finding advanced cancers, but <a href=\"http:\/\/www.ncbi.nlm.nih.gov\/sites\/entrez?orig_db=PubMed&amp;db=pubmed&amp;cmd=Search&amp;term=%22The%20New%20England%20journal%20of%20medicine%22%5BJour%5D%20AND%201403%5Bpage%5D%20AND%202007%5Bpdat%5D\">results in far fewer polypectomies.<\/a><\/li><li>May identify abnormalities outside the colon.<\/li><\/ul><p>It also has some disadvantages:<\/p><ul><li>Radiation exposure.<\/li><li>May miss smaller polyps and even some larger ones: CT colonography <a href=\"http:\/\/www.ncbi.nlm.nih.gov\/sites\/entrez?orig_db=PubMed&amp;db=pubmed&amp;cmd=Search&amp;term=%22The%20New%20England%20journal%20of%20medicine%22%5BJour%5D%20AND%201207%5Bpage%5D%20AND%202008%5Bpdat%5D\">failed to detect a lesion measuring 10 mm or more in diameter in 10% of patients<\/a> and <a href=\"http:\/\/www.ncbi.nlm.nih.gov\/sites\/entrez?orig_db=PubMed&amp;db=pubmed&amp;cmd=Search&amp;term=JAMA%5BJour%5D%20AND%202453%5Bpage%5D%20AND%202009%5Bpdat%5D\">missed 15% of advanced cancers<\/a> measuring over 6 mm.<\/li><li>Still requires thorough bowel prep (clear liquid diet, laxatives, large quantities of bad-tasting oral solutions), which some patients find to be the most objectionable part of colonoscopy.<\/li><li>Requires insertion of rectal tube and insufflation of air.<\/li><li>If a lesion is seen, optical colonoscopy will be required as follow-up.&nbsp;About <a href=\"http:\/\/www.nejm.org\/doi\/full\/10.1056\/NEJMoa070543\">8% of patients will end up getting both procedures. <\/a><\/li><li>May identify abnormalities outside the colon.<\/li><\/ul><p>You will notice that identification of abnormalities outside the colon is listed as both an advantage and a disadvantage. Assessments of risk\/benefit ratio differ. In <a href=\"http:\/\/radiology.rsna.org\/content\/236\/2\/519.long\">a 2005 study<\/a> of 500 patients published in <em>Radiology<\/em>, CT colonoscopy found &ldquo;a substantial number&rdquo; of clinically significant findings, including aneurysms and a renal carcinoma; but it did not establish whether finding them improved outcomes. 28% of the significant findings had already been diagnosed prior to colonoscopy; and the patient with the renal carcinoma declined treatment, since he already had metastatic colon cancer.&nbsp;In <a href=\"http:\/\/www.ncbi.nlm.nih.gov\/pmc\/articles\/PMC2607491\/\">a 2009 study<\/a> of 143 patients, 98% of patients had at least one incidental finding outside the colon. 24% of these required further evaluation, with 73 imaging studies, 30 lab studies, 44 clinical visits, 6 medical procedures, and 44 return visits over a mean period of 38 months. The cost was estimated at $248 per patient. They did not assess whether these evaluations improved eventual patient outcomes.<\/p><p>Writing in the journal <em>Radiology<\/em>,&nbsp;Dr. William Casarella, a radiologist at Emory University School of Medicine, tells the <a href=\"http:\/\/radiology.rsna.org\/content\/224\/3\/927.full\">story of his own virtual colonoscopy<\/a>. His colon was normal; but the CT also showed areas outside the colon, revealing a kidney lesion, a 2 cm. mass in the liver, and multiple non-calcified nodules in the bases of both lungs. These findings led to the following tests and interventions:<\/p><ul><li>A contrast-enhanced CT of the abdomen (with more radiation) showed that the kidney lesion was a benign cyst, but the liver mass was not.<\/li><li>A high-resolution lung CT (more radiation) confirmed lung nodules.<\/li><li>A CT-guided (more radiation) liver biopsy (more risks) showed necrotic tissue, no definitive findings.<\/li><li>A PET scan (more radiation) was negative.<\/li><li>Video-aided thoracoscopy<\/li><li>3 wedge resections of the right lung (requiring the lung to be collapsed), resulting in a diagnosis of histoplasmosis (benign, no treatment indicated).<\/li><\/ul><p>The lung surgery led to:<\/p><ul><li>5 hours in the recovery room before awakening from general anesthesia.<\/li><li>Chest tube, subclavian central venous catheter, nasal oxygen catheter, epidural catheter, arterial catheter, subcutaneous heparin injections, prophylactic antibiotics, IV narcotics (each with associated risks).<\/li><li>Excruciating pain requiring narcotics for 2 weeks.<\/li><li>4 weeks of disability.<\/li><li>Persistent chest pain due to surgical interruption of intercostal nerves.<\/li><\/ul><p>The total cost was over $50,000.<\/p><p>This is an atypical example, but it underlines the potential <a href=\"http:\/\/www.sciencebasedmedicine.org\/index.php\/overdiagnosis\/\">dangers of too much information<\/a>.&nbsp;Sometimes ignorance is bliss. Dr. Casarella would have been better off had he not been screened for colon cancer at all. I support the USPSTF recommendations, but it is important not to over-rate the value of these tests. The public perception is &ldquo;get this test: it will save your life.&rdquo; The reality is more complicated. Screening tests can have false positive and false negative results. They don&rsquo;t always provide clear black and white answers, and they don&rsquo;t save as many lives as the public tends to think. While statistically&nbsp;benefiting&nbsp;the population, they may be hazardous to the health of some individuals. 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