Page 43 Complete Your CE Test Online - Click Here expert gastroenterologist to fully evaluate risk and perform colonoscopy as indicated. See Colorectal Cancer Prevention and Early Detection at colonandrectumcancerearlydetection/index or call 1-800-ACS-2345 for the details of high risk screening. Double-contrast barium enema This is a much older X-ray test that can detect large polyps and cancers by imaging the entire colon, although it is somewhat less sensitive than colonoscopy in finding smaller polyps or cancers. Barium sulfate flows into the colon through a tube placed in the anus to partly fill the colon, then air is introduced to expand the lumen of the colon and improve visibility. The double-contrast barium enema (DCBE) requires a full bowel preparation but does not usually involve sedation. However, polyps cannot be removed nor biopsies performed during the test. It also involves exposure to a low dose of radiation, and is not used much because of the ready availability of colonoscopy. Also, as time goes on, fewer radiologists know how to perform the procedure. A standard or optical colonoscopy is needed if abnormalities are found. False positive tests can occur. The American Cancer Society recommends it as an option for CRC screening every five years [14]. The U.S. Preventive Services Task Force does not recommend it as a screening method for colorectal cancer in part because it is less sensitive than colonoscopy. Computed tomographic colonography (or virtual colonoscopy) This test requires the same preparation as standard colonoscopy, but is less invasive and does not require sedation. Air is still pumped in through the anus before the patient goes through the CT scanner. However, polyps cannot be removed nor biopsies performed during the test. It also involves exposure to a low dose of radiation. It requires an optical colonoscopy if abnormalities are found, preferably on the same day – otherwise another prep must be done and there will be some delay. The American Cancer Society endorses the CT colonography as similar to the standard colonoscopy in detecting invasive cancers and polyps that are a centimeter or greater in size, but it has not yet been shown to reduce CRC deaths [19]. As of early 2016, the U.S. Preventive Services Task Force does not recommend this screening method, and some insurance companies do not cover it [284]. Stool DNA testing This is a newer type of colorectal cancer screening test, exemplified by the Cologuard® test (FDA-approved in 2014), that uses a kit to collect a stool sample at home and requires no dietary changes or other preparation. In one study of people who were at average risk for developing colon cancer and had no symptoms of colon problems, this test detected more cancers and adenomas than the FIT test (i.e. it was more sensitive). However, the Cologuard test also had more false- positive results than the FIT, so it was not as specific [200]. This type of test is recommended by the American Cancer Society as a method to detect colon cancer although, like FOBT, it will miss most polyps. Their newest guidelines recommend that this test be performed every three years [14]. Like the FOBT, it requires an optical colonoscopy if abnormalities are found [11]. Unlike the FOBT, it is expensive and anyone who wants this these should check with their insurance plan to be sure that it will be covered. The U.S. Preventive Services Task Force does not recommend this screening method as of early 2016, but is reviewing the evidence for possible inclusion at a later date [284]. Blood test for colorectal cancer screening approved by FDA, April 2016 The Epi proColon is a new blood test offered as a screening test for patients who are at average risk for colon cancer if they are due for screening but do not want any of the other approved tests for colon cancer. It is not recommended for people at high risk or as a confirmation test for colorectal cancer [87]. The Epi proColon test has not been on the market long enough for the American Cancer Society or the U.S. Preventive Services Task Force to weigh in on it, but the online brochure for the test has a lot of information. It mentions that the Epi proColon test was positive two out of ten times when colorectal cancer was not present, and negative three out of ten times when colorectal cancer was present. The false negative rate of 30% seems somewhat high, and could be misleading to a lot of patients (see “Limitations of cancer screening”). In addition, the patient who has a positive test will need to be referred for a diagnostic colonoscopy [87]. Complications of colonoscopy and sigmoidoscopy Many colonoscopies are used for follow-up of an abnormal screening test, but colonoscopy and sigmoidoscopy are also considered first-line screening options for colorectal cancer. Most screening tests are less invasive than these, which can, on rare occasions, have more serious complications than other screening tests. Because of that, they deserve special mention here. The preparation for colonoscopy, which involves a clear liquid or low- residue diet, laxatives and sometimes enemas, can cause electrolyte imbalance and dehydration, especially in elders and those with co- morbidities. Sigmoidoscopy prep is usually briefer and likely involves less risk. Serious complications of colonoscopy and sigmoidoscopy can include bleeding, bowel perforation, and bleeding, which are more common when polyps are removed. According to the American Society for Gastrointestinal Endoscopy, serious complications in people undergoing screening colonoscopy number fewer than three per every 1000 patients [42]. However, the National Cancer Institute notes that, when polyps are removed, seven to nine per every 1000 patients have a major complication such as perforation or bleeding [119,221,299]. Note that bleeding can present during or after the colonoscopy, and for up to several weeks after. Most patients are sedated during the colonoscopy procedure, which can also cause complications such as hypoxia, hypotension, or shock, and cardiac events such as arrhythmia or myocardial infarction (MI); this is somewhat dependent on what medications are used. One study also found slightly higher incidence of cardiovascular events in the month after the procedure, including angina, myocardial infarction, stroke or transient ischemic attack (about 1.4 events per every 1000 patients). This was in a Medicare population so most of the patients were in a higher-risk age group [42]. Less severe complications for patients undergoing colonoscopy and sigmoidoscopy include bloating and abdominal pain or discomfort, usually due to air being pumped in during colonoscopy to allow visibility of the intestinal walls [42]. Lung cancer screening for people with a heavy smoking history This is a relatively new addition to the cancer screening test recommendations, but it only applies to people who are or have been heavy smokers. This screening recommendation is based on results from the National Lung Screening Trial (NLST), which randomly assigned participants to one of two ways of detecting lung cancer: low-dose helical computed tomography (CT), also called spiral CT; and standard chest X-ray. Helical CT uses X-rays to obtain a multiple-image scan of the entire chest, while a standard chest X-ray produces a single image of the whole chest in which anatomic structures overlie one another. Each participant had three annual exams with either helical CT or chest X-ray. The NLST had more than 53,000 US participants aged 55 to 74 who had smoked at least 30 pack-years but who were otherwise fairly healthy and had no signs, symptoms, or history of lung cancer (pack-years are calculated by multiplying the average number of packs of cigarettes smoked per day by the number of years a person has smoked). The study findings revealed that participants who received low-dose helical CT scans had a 15% to 20% lower risk of dying from lung cancer than participants who received standard chest X-rays. This is equivalent to approximately three fewer deaths per 1000 people screened in the CT group compared to the chest X-ray group over a period of about seven years of observation (17.6 per 1,000 in the CT group versus 20.7 per 1,000 in the chest X-ray group). On average over the three rounds of screening exams, 24.2% of the low-dose helical CT screens were positive and 6.9% of the chest X-rays were positive. In both arms of the trial, the majority of positive screens led to additional tests whether or not cancer was found [177]. Adenocarcinomas and squamous cell carcinomas were detected more frequently at the earliest