Colorectal Cancers: Screening, Diagnosis, and Treatment
Presented by: Drs. Sidney Winawer, Martin Weiser, and Leonard Saltz 71 minutes
Screening & Diagnostic Tests
Colorectal cancer screening and diagnosis may involve one or more of the following 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.
Fecal Immunochemical Test (FIT)
Also called an immunochemical fecal occult blood test (iFOBT), this newer kind of colorectal cancer screening test also finds hidden blood in the stool, but it does so by reacting to a part of the hemoglobin molecule (the protein found in red blood cells). Unlike traditional fecal occult blood testing, FIT does not require the patient to avoid certain foods or drugs before the test.
Flexible Sigmoidoscopy
This examination is similar to the colonoscopy exam, but it uses a shorter tube to inspect the lower part of the colon.
Virtual Colonoscopy
Virtual colonoscopy is a technique that uses CT scans to create a 3-D image that can be used to evaluate the bowel. While this technique may be useful for some people who can't have or don't want to have an invasive test such as colonoscopy, it does not allow for a biopsy or polyp removal at the same time if an abnormality is found. Moreover, the bowel cleansing required before the test is the same as that for conventional colonoscopy.
Our Colorectal Cancer Screening Guidelines
Individuals at Average Risk
Our doctors recommend that average-risk individuals with no symptoms undergo a colonoscopy every ten years, beginning at age 50.
If an individual's first-degree relative had a colon cancer or premalignant polyp diagnosed after age 60 or if an individual has two second-degree relatives (grandparent, grandchild, uncle, aunt, nephew, niece, half-sibling) with colon cancer, we recommend colonoscopy at least every ten years, beginning at age 50.
Individuals at High Risk
For individuals with a first-degree family member (parent or sibling) who had a colorectal cancer or a premalignant (adenomatous) colorectal polyp detected before the age of 60, our doctors recommend colonoscopy at least every five years beginning either at age 40 or ten years before the youngest age of the family member's diagnosis (of either colon cancer or premalignant polyps).
For individuals with a family history of familial adenomatous polyposis (FAP), our doctors recommend annual sigmoidoscopy beginning between the ages of 10 and 15, or earlier if symptoms develop.
For individuals with a family history of hereditary nonpolyposis colorectal cancer (HNPCC), our doctors recommend annual colonoscopy beginning between the ages of 20 and 25, or five to ten years before the earliest diagnosis in the family -- whichever comes first.
For more information about our guidelines for colorectal cancer screening, see the Prevention & Screening area of the Web site.
