Here are some of the tools used to detect colorectal cancer.

• A fecal occult blood test, or FOBT, is a test used to check for hidden blood in the stool. Sometimes cancers or polyps can bleed, and FOBT can detect small amounts of bleeding.

• A sigmoidoscopy is an examination of the rectum and lower colon -- or sigmoid colon -- using a lighted instrument called a sigmoidoscope.

•  A colonoscopy is an examination of the rectum and entire colon using a lighted instrument called a colonoscope.

• A virtual colonoscopy, which requires the same preparation as a standard colonoscopy, is done with an external scanning machine as opposed to a device inserted into the colon.