Colorectal Cancer Screening: What’s Accurate and Cost-Effective?

SCREENING METHODS
Current screening methods for CRC can be divided into two distinct categories: indirect and direct.¹ Indirect screening tests include FOBT, fecal immunochemical testing, and stool DNA testing. Cancers are identified by detection of byproducts in the patient’s stool, such as blood or epithelial cells containing DNA of the adenomatous polyposis coli gene. These tests are simple to perform, have high specificity, and are relatively inexpensive, but they need to be repeated annually and have poor sensitivity.¹ Positive test results of indirect screening often warrant further diagnostic testing, ultimately utilizing one of the direct screening methods.

Direct screening methods used to detect CRC—from least to most frequently employed—include barium enema (BE), CT colonography (CTC), and colonoscopy. Another direct method, flexible sigmoidoscopy, is not frequently used today, and when used, serves only as an intermediate step to colonoscopy. Direct screening provides visualization of the contour of the colon wall, the internal mucosa, and abnormal architecture. It is important to keep in mind that these tests require that the patient adhere to pretest preparation, may require patient sedation, and are more invasive and costly than indirect tests.¹

Although the USPSTF has established recommendations for both test types, questions still remain about what constitutes the most cost-effective and accurate combination of screening tests for detecting CRC.⁸

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