Screening Methods

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Comparing Screening Methods for Average Risk Patients
Tests that Detect Adenomatous Polyps and Cancer
Colonoscopy	Every 10 years	Most sensitive test for small and large polyps and cancers. Examines the entire colon, polyps can be removed and biopsied during the procedure.	Expensive, requires complete bowel cleansing. Normally uses sedation and requires someone to accompany patient, Rare instances of bowel perforation and bleeding. May not be covered by insurance.
Double-contrast barium enema	Every 5 years	Visualizes the entire colon, can detect most cancers, and the majority of large polyps. Helps patients who cannot complete a colonoscopy or where colonoscopy is not medically appropriate. Less expensive.	Requires complete bowel preparation. May be uncomfortable. An experienced radiologist is critical to quality exam. Colonoscopy is still required to biopsy lesions or removed polyps.
CT-colonography (virtual colonoscopy)	Every 5 years	Does not require sedation. No recovery time, patients can drive home or return to work. Finds cancer and large polyps at the same rate as colonoscopy. May find problems outside the colon as well.	Requires complete bowel preparation. Colonoscopy is required to biopsy and remove polyps. Technology and radiologist training are growing but not complete. May not detect non-polypoid colorectal neoplasms. May not be covered by insurance. False-positive problems identified outside the colon may require unnecessary follow-up tests.
Flexible sigmoidoscopy	Every 5 years	Can be done by primary care physician or trained nurse practitioner. Does not require sedation	Will miss polyps or cancers in the right colon beyond the reach of the scope. If polyps are found, colonoscopy and addition bowel preparation are required. Can be uncomfortable.
Tests that Primarily Detect Cancer
gFOBT: Guaiac-based stool test	Every year	Inexpensive, is done privately at home, can be offered to many people through community programs, including those without primary care or insurance.	Not very sensitive to polyps, will miss some cancers. Needs to be done correctly over three days. Requires diet and drug restrictions. Patients must handle stool. Has a high false positive rate that requires follow-up colonoscopy for about 1 in 3 tests.
FIT: Immunochemical stool test	Every year	Has no diet or drug restrictions prior to the test. Limits blood detected to colon and rectum . Is more sensitive than guaiac-based tests for cancer. May be simpler for patients to do.	Will miss some cancers and most advanced polyps. More expensive than gFOBT. All positive tests require colonoscopy follow-up.
Stool DNA test	Not yet known	Done at home privately. Not necessary to handle stool. Collection kit shipped directly to patient. No special diet prep required.	May not find all cancers or large polyps. Requires prompt, ice-pack shipment to special labs. Significantly more expensive than gFOBT or FIT. Colonoscopy follow-up necessary for positive test.