Colon and Rectal Cancers - Diagnosis

General Screening Guidelines

Individuals should discuss with their doctors the risks and benefits of all screening procedures. Some controversy exists over how often people without risk factors for cancer should be screened and which detection method should be used for them.

Guidelines for Adults Age 50 and Over with Average Risk

The following are the five screening options recommended for people age 50 and over who have no symptoms and no family history of colon cancer:

• Fecal occult blood test (FOBT) or fecal immunochemical test (FIT) every year
• Flexible sigmoidoscopy every 5 years
• FOBT or FIT every year plus sigmoidoscopy every 5 years
• Double-contrast barium enema every 5 years
• Colonoscopy every 10 years

Choosing between Colonoscopy and Sigmoidoscopy. The choice between colonoscopy and sigmoidoscopy for routine screening for older adults with average risk is an area of intense debate. The issues are as follows:

• Sigmoidoscopy is less costly, less invasive, quicker, and safer than colonoscopy. Although it allows inspection of only the left side of the colon, any abnormal findings from sigmoidoscopy trigger a full colonoscopy. Therefore, experts estimate that sigmoidoscopy can detect 80% of all significant problems.
• Colonoscopy is more sensitive than any other current screening methods for detecting colon cancer. It can find 75 – 90% of colorectal cancers. If the goal were to reduce the number of cancer cases, regardless of cost, colonoscopy would be the preferred approach. Colonoscopy, however, is more expensive than sigmoidoscopy and has a slightly higher risk for complications (bowel tears or bleeding when a polyp is removed).