What are the screening options for colon and rectal cancer?

Updated: Apr 06, 2021
  • Author: Burt Cagir, MD, FACS; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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Answer

Screening techniques include the following:

  • Guaiac-based fecal occult blood test (FOBT): Perform FOBT yearly by testing 2 samples from each of 3 consecutive stools. If any of the 6 sample findings is positive, recommend that the patient have the entire colon studied via colonoscopy or flexible sigmoidoscopy. FOBT has significant false-positive and false-negative rates.

  • Stool DNA screening (SDNA): SDNA screening is done using polymerase chain reaction of sloughed mucosal cells in stool. This test evaluates for genetic alterations that lead to the cancer formation. Compared with no testing, SDNA testing is cost effective and has high sensitivity for invasive cancer.

  • Fecal immunochemical test (FIT): Fecal immunochemical testing uses a monoclonal antibody assay to identify human hemoglobin. This test is more specific for lower GI tract lesions. The presence of the globin molecule is indicative of bleeding in the colon and rectum because the globin molecule is broken down during passage through the upper GI tract. This test is probably the wave of the future in fecal occult blood testing and may serve as screening in certain populations. FIT has comparable sensitivity for the detection of proximal and distal advanced neoplasia. [36]

  • Rigid proctoscopy: Rigid proctosigmoidoscopy can be performed without an anesthetic, allows direct visualization of the lesion, and provides an estimation of the size of the lesion and degree of obstruction. This procedure is used to obtain biopsies of the lesion, assess ulceration, and determine the degree of fixation. Rigid proctoscopy has proved to be a highly reproducible method of determining the level of rectal cancer and does not depend on the operator and on the technique. Therefore, it gives an accurate measurement of the distance of the lesion from the anal verge; the latter is critical in deciding which operation is appropriate. The anal verge should be used as preferred landmark because the lowest edge of the rectal cancer and the anal verge can be visualized simultaneously during rigid proctoscopy evaluation. In conclusion, the level of rectal cancer must be confirmed by rigid proctoscopy. [37]

  • Flexible sigmoidoscopy (FSIG): Perform this test every 5 years. Biopsy any lesions identified, and perform a full colonoscopy. With flexible sigmoidoscopy, lesions beyond the reach of the sigmoidoscope may be missed. FSIG introduces significant variability for the level of rectal cancer and level of rectum itself. Therefore, FSIG should not be used to determine the level of the rectal cancer. [37] Screening with flexible sigmoidoscopy is associated with significant decreases in the incidence of colorectal cancer (in both the distal and proximal colon) and in colorectal cancer mortality (distal colon only). [38]

  • Combined glucose-based FOBT and flexible sigmoidoscopy: Theoretically, the combination of these two tests may overcome the limitations of each test.

  • Double-contrast barium enema (DCBE): Although barium enema is the traditional diagnostic test for colonic polyps and cancer, the United States Preventive Services Task Force (USPSTF) did not consider barium enema in its 2008 update of colorectal cancer screening recommendations. The USPSTF noted that barium enema has substantially lower sensitivity than modern test strategies and has not been studied in trials of screening trials; its use as a screening test for colorectal cancer is declining. [39]

  • CT colonography (CTC): Virtual colonoscopy (CTC) was introduced in 1994. After bowel preparation, the thin-cut axial colonic images are gathered in both prone and supine positions with high-speed helical CT scanner. Then, the images are reconstituted into a 3-dimensional replica of the entire colon and rectum. This provides a good visualization of the entire colon, including the antegrade and retrograde views of the flexures and haustral folds. Because this is a diagnostic study, patients with positive findings should undergo colonoscopic evaluation the same day.

  • Fiberoptic flexible colonoscopy (FFC): FFC is recommended every 5-10 years. Colonoscopy allows full visualization of the colon and excision and biopsy of any lesions. The likelihood is extremely low that a new lesion could develop and progress to malignancy between examinations.


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