Cancer of the colon and rectum is the third most common type of cancer in the United States. The risk for men and women to develop colon cancer or rectal cancer is about 5-6 percent over a lifetime. Several large studies have shown that a history of colon or rectal cancer in a 1st degree relative (parent, brother, sister, or child) increases an individual's chance of developing cancer of the colon or rectum. Family history of pre-cancerous colorectal polyps (mushroom-like growths) also increases one’s risk.
The American Cancer Society, the American Gastroenterological Association, and the National Cancer Institute all recommend men and women begin screening for colorectal cancer at age 50. People with family history should consider screening at a younger age. The first step in prevention starts with a healthy lifestyle. Eating a balanced diet, avoiding excessive alcohol and tobacco use, and exercising are all good ways to reduce cancer risks.
An important way to prevent cancer of the colon or rectum is by getting the appropriate screening tests. Removal of pre-cancerous polyps detected through screening can prevent the development of cancer altogether. Several tests and procedures are used to screen for colorectal cancer. For those at average risk, screening is recommended to begin at age 50. Screening options include: yearly fecal occult blood test and flexible sigmoidoscopy every five years, colonoscopy every 10 years, or double contrast Barium enema every five years.
Fecal occult blood test screening consists of examining two or three consecutive stools for microscopic blood findings. Patients with a positive test on any specimen should be followed up with a colonoscopy.
Flexible sigmoidoscopy is a procedure in which the doctor looks inside the rectum and the lower portion of the colon (sigmoid colon) through a flexible, lighted tube called a sigmoidoscope. The doctor may collect samples of tissues or cells for closer examination and remove some polyps within view. Fecal occult blood test and sigmoidoscopy may be used as a combined screening tool, with fecal occult blood test being performed yearly combined with flexible sigmoidoscopy every five years.
A colonoscopy allows inspection and tissue sampling of the rectum and large intestine by inserting a flexible tube with an attached camera throughout the rectum. It allows for greater visualization of the large bowel (upper colon) than the sigmoidoscopy, thereby permitting the detection and removal of polyps and biopsy of cancer throughout the colon. It is considered to be the most accurate screening test for polyps and cancer.
The double-contrast Barium enema consists of a series of x-rays of the colon and rectum. The x-rays are taken after the patient is given an enema, followed by an injection of air. The barium outlines the intestines so that abnormal growths can be seen.
Screening recommendations for those with a family history
- In people with either one first-degree or two second-degree relatives (for instance, an aunt, uncle or grandparent) with colon cancer or pre-cancerous polyps, the above screening is recommended beginning at age 40 instead of 50, with a colonoscopy as the preferred method. A colonoscopy should be repeated at least every five years if the results are negative.
- Colonoscopy screening should begin at 40 years or 10 years earlier than the earliest case of colon cancer in the family. A colonoscopy should be repeated at least every five years if the results are negative.
- When a hereditary colorectal cancer syndrome is suspected or present in a family, members may begin screening at much younger ages and more frequently. In some cases, screening may begin in childhood or early adulthood and will often involve annual colonoscopy (see below for more information).
Even stronger family histories of colon cancer may suggest an inherited colon cancer syndrome. People with a family history of colorectal cancer in several close relatives and across generations, especially if these cancers occur at a young age, may benefit from genetic counseling and genetic testing for the inherited syndromes of colon cancer. You can learn more about hereditary colorectal cancer issues through our Colorectal Cancer Risk and Prevention Clinic. To schedule an appointment, call the clinic coordinator at 617-632-2178.