What Are the Different Methods of Colorectal Cancer Detection?

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  • Written By: Mary McMahon
  • Edited By: Nancy Fann-Im
  • Last Modified Date: 25 October 2018
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Methods for colorectal cancer detection can include physical examinations, medical imaging studies, and stool sample analysis. People over the age of 50 need regular testing at intervals that can vary depending on the type of testing a doctor uses. Some patients may be at increased risk of developing colorectal cancer and could need earlier or more frequent screening. This may be available for free or at low cost to people of low income through a cancer assistance program.

In a physical examination, a doctor can insert a gloved finger into the rectum to check for irregularities. He can also inspect the area visually for any signs of irritation that might indicate a health problem. The digital rectal exam has a number of drawbacks as a screening method. Although it is inexpensive, it will only identify cancers very near the rectum, and only when the cellular changes are very obvious.


Medical imaging studies can be a better choice. The gold standard for colorectal cancer detection is the colonoscopy, where a camera on a flexible tube is passed through the rectum and up into the colon. If the doctor spots polyps and other abnormalities, she can take a biopsy sample immediately. Patients can also receive a sigmoidoscopy, which looks at a lesser extent of the colon, as well as ultrasound and computer tomography (CT) colonography. CT colonography is also known as virtual colonoscopy because it provides a series of images of the colon, without the invasive examination.

The barium enema is another option for colorectal cancer detection. In this test, the patient receives an enema with radio-opaque material, and a series of x-rays can reveal abnormalities in the bowel. This test can be uncomfortable. One disadvantage with this procedure, CT colonography, and ultrasound is that if there are polyps in the bowel, the patient needs another appointment to remove them.

Fecal samples can also be helpful in colorectal cancer detection. A fecal occult blood sample can look for signs of blood in the stool, indicative of lesions and bleeding in the intestinal tract. A doctor can also request an immunochemical test to search for blood in the stool. DNA testing is available to detect some forms of cancer by looking for their genetic signatures. This option is much more expensive.

When a doctor provides information about options for colorectal cancer detection, patients can request more details about specific tests. The colonoscopy is often the best option, as it will provide detailed images of the colon for the benefit of the care provider. While it is invasive and can be unpleasant, it may catch signs of clinical problems before other tests can, and this may result in a better chance at a good outcome if colorectal cancer does develop.



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