Screening & Diagnosis

CancerSmart Web Cast Our experts -- Drs. Winawer, Saltz, and Weiser -- discuss the latest advances in screening, diagnosis, and treatment of colorectal cancer watch video

Screening & Diagnostic Tests

Colorectal cancer screening and diagnosis may involve one or more of a number of procedures:

• Colonoscopy

  This examination allows the doctor to inspect the rectum and colon, using a thin tube that has a light on the end. It is inserted into the rectum while the patient lies on his or her side. Patients often receive a mild sedative during this procedure to ensure their comfort. Any polyps or other growths that are found during these examinations are usually removed at the time and sent to a laboratory for examination.

  A ten-year study by Memorial Sloan-Kettering investigators showed that colonoscopy was more effective than another screening technique called double-contrast barium enema for detecting precancerous colon polyps. The findings of this study were the first to show that the various surveillance tools used to follow patients who have had colon polyps removed are not equally reliable. Moreover, unlike barium enema, colonoscopy allows the doctor to remove any polyps at the time of the examination.

• Fecal Occult Blood Test

  A test to check for blood in the stool. Small samples of stool are placed on special cards and sent to a doctor or laboratory for testing. The patient is asked to follow a special diet and then bring in stool specimens (usually applied to small, folded cards) from three successive days. Blood in the stool may be a sign of colorectal cancer.

• Flexible Sigmoidoscopy

  This examination is similar to the colonoscopy exam, but it uses a shorter tube to inspect the lower colon.

• Virtual Colonoscopy

  Virtual colonoscopy is a new technique that uses CT scans to create a 3-D image that can be used to evaluate the bowel. At this time, it is still a research tool and is not generally available. It is also important to note that, while this is a promising technique, it does not allow for a biopsy or polyp removal at the same time an abnormality is found.