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Colon Cancer Screening Options

    • Each year, between 130,000 and 150,000 people in the U.S. are diagnosed with colon cancer, and more than one in three will succumb to it. But if followed, the American Cancer Society’s colon screening guidelines could reduce those deaths by up to one half.

      First some basics:

      • Colorectal cancer describes cancer occurring in either the colon or rectum.
      • Colorectal cancer is the second leading cause of cancer-related deaths in the U.S.
      • The majority of colorectal cancer patients are 50 years or older
      • The majority of colorectal cancers begin as polyps in the colon or rectum.
      • People at average risk (most of us) should be screened starting at age 50.
      • Only 50 to 55 percent of Americans that should be screened are.

      When it comes to screening options, there are all sorts of opinions on what is best because there are several different tests with varying levels of reliability, invasiveness and cost.

    • Fecal tests

    • Fecal tests analyze the stool for traces of blood. Cancer tissues are packed with blood vessels, so they tend to cause small levels of blood in the stool. If blood is found, a colonoscopy is needed to either diagnose or rule out colorectal cancer.

      The tests are not 100 percent accurate, and it is possible for them to react even when cancer is not present – a “false positive.”

    • Double-contrast barium enema

    • DCBE tests use X-ray technology to analyze the colon and rectum for signs of polyps and/or cancer.

      The procedure takes about 30 to 45 minutes and uses a combination of liquid (barium sulfate) and air to fill out the colon. Once the colon is expanded, a series of X-rays is taken. If any abnormalities are found, a colonoscopy is needed.

    • C.T. colonography – the virtual colonoscopy

    • C.T. technology uses advanced computers and X-rays to create a three-dimensional virtual model of the body’s tissues. To get a clear view of the colon’s walls, though, it is necessary to inflate the colon with air for the duration of the scan. If any abnormalities are found, a colonoscopy is needed.

    • Flexible sigmoidoscopy

    • The sigmoid colon is the last section of the colon. It resides in the pelvic area and connects the rectum to the descending colon – which extends down the left side of the abdomen. Between 65 to 70 percent of cancer-causing polyps occur within the sigmoid colon.

      A sigmoidoscopy uses a flexible tube with a camera attached to the end to inspect the rectum and sigmoid colon for cancer and/or polyps. The exam doesn’t typically require sedation, but if any abnormalities are found, a colonoscopy is necessary.

    • Colonoscopy

    • A colonoscopy uses a flexible tube with a camera to examine the entire colon for polyps and/or cancer. Unlike other screening methods, when polyps are identified during a colonoscopy they can be removed, reducing the rpatients risk of developing cancer. Once removed, the polyps are evaluated to help determine the patient’s risk of developing colorectal cancer.

      Because they are more invasive than the other screenings, colonoscopies require that the patient be partially sedated, meaning they remain in a semi-conscious state. (See a video on what happens during a colonoscopy.)

    • Which colon screening is best?

    • If you exclude things like discomfort and the cost of the exam, colonoscopy is the best choice. But some patients prefer either less-invasive alternatives that don’t require sedation or are concerned about the higher cost of a colonoscopy compared to either sigmoidoscopy or DCBE.

      When sigmoidoscopy, DCBE or C.T. colonography (virtual colonoscopy) are used in lieu of colonoscopy, they should be performed more frequently (every five years or less) and in conjunction with annual fecal tests.

      It is also worth noting that when any of the other screenings find abnormalities, a colonoscopy is needed. So patients and organizations trying to limit the cost of the screening may end up paying more.

    • Accuracy concerns in colon screening

    • Sigmoidoscopy
      A study published in the New England Journal of Medicine found that sigmoidoscopy in conjunction with fecal testing successfully identified 75 percent of colorectal cancers. Meaning, of course, that 25 percent of colorectal cancers went undiagnosed using the less-invasive and less-expensive screening.

      Virtual Colonoscopy
      This technology is relatively new and, consequently, has not been either proven or disproven as a reliable screening method.

    • Future colon ccreening possibilities – DNA stool testing

    • Two impressive colon cancer technologies that could make a huge impact on the way we screen for and treat colon cancer are worth mentioning.

      Current fecal testing methods mainly look for the presence of blood in the stool. But they are not wholly reliable. Researchers are currently working to create an all-inclusive DNA test that could identify colon cancer cells in the stool.

      If a test capable of recognizing all of the different types of colon cancer can be created, colon cancer screening could be come as easy and non-invasive as regular fecal tests.

      Jeffrey Cronk M.D. is the medical director of cancer services at Sutter Delta Medical Center Opens new window in Antioch. He is triple board certified in internal medicine, medical oncology and hematology.

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