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Fecal occult or hemoccult blood test
Masses in the colon and rectum are known to bleed early in their development. An inexpensive, easy-to-use screening tool is the guaiac test for occult (hidden) blood in the stool. A small amount of stool is placed on a plastic slide or special paper and examined under a microscope for minute traces of blood.
Patients are asked to eat a lot of fiber and restrict their consumption of red meat, vitamin C, and NSAIDs for several days prior to testing. Since adenomas or tumors bleed intermittently, samples are taken from three successive stool specimens. Positive results indicate the need for complete examination of the colon.
One advantage to this test is that it can be performed at home. However, some polyps and cancers don't bleed, or samples may not be taken when abnormalities are bleeding. So it can give a person with cancer a negative result. For this reason, among others, some doctors say other tests for colon cancer should be performed in addition to—or instead of—the fecal occult blood test (FOBT).
Other stool tests now being developed identify the presence of very early colon cancer by detecting mutated cells that are shed into the stool.
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