The latest guideline review reassessed the evidence for colorectal cancer screening tests that fall broadly into two categories:
Tests that are more likely to detect both cancer and premalignant polyps
Tests in this category are structural exams, including flexible sigmoidoscopy (FSIG), optical colonoscopy (CSPY), double contrast barium enema (DCBE), and computerized tomographic (CT) colonography. The higher likelihood of polyp detection with the use of these tests substantially increases opportunities for removal of polyps and the associated prevention of colorectal cancer.
Tests that are primarily effective at finding cancer early
Fecal (stool) tests include: guaiac-based and immunochemical-based fecal occult blood tests (gFOBT & FIT), and stool DNA test (sDNA). These tests primarily identify the existence of colorectal cancer. Some precancerous polyps may be detected by these tests, providing an opportunity to remove them and prevent colorectal cancer, but the opportunity for prevention is both limited and incidental and can not be the primary goal of colorectal cancer screening with these tests.
The panel also sought to address a number of quality issues related to each form of testing, as well as concerns about the complexity of offering multiple screening options to adults, and the degree to which the range of testing options, performance, costs, and demands on patients poses a significant challenge for shared decisions. An overriding goal of this update is to provide a practical guideline for physicians and the public to assist with informed decision making related to colorectal cancer screening.