There are four basic tests for colon cancer: a stool test (to check for blood); a barium enema (x-ray) test; sigmoidoscopy (inspection of the lower colon); and colonoscopy (inspection of the entire colon). All four can detect cancers in the early stages, when treatment is most beneficial, but colonoscopy is the most accurate.
A newer text, CT colonogrpahy ("virtual colonoscopy"), uses CT scanning to evaluate the colon, but it requires the same through bowel cleansing as colonoscopy.
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