Bowel Cancer

Tests
The feasibility of recommending that all adults begin regular bowel cancer screening when they reach 50 is currently being tested in the UK. Deciding which screening test to use and how often ultimately depends on a person's individual risk of bowel cancer. If a first-degree relative has had bowel cancer, for instance, screening should start 10 years prior to the age that relative was diagnosed to help identify possible pre-cancerous polyps. There are four common screening tests for detecting bowel cancer:

• Faecal occult blood (FOB) test is a test for hidden blood in the stool.
• Sigmoidoscopy is an examination of the rectum and lower colon with a rigid or flexible lighted instrument. 
• Double barium contrast enema is a series of x-rays of the colon and rectum. The patient is given an enema with a white, chalky solution that outlines the colon and rectum on the x-rays.
• Colonoscopy is an examination of the rectum and entire colon with a lighted instrument. It may be the most useful, but it is also the most invasive.

In addition to these, a doctor may perform a rectal examination to feel for a rectal mass with a gloved finger. Most bowel cancers, however, are beyond the reach of a finger and have no symptoms; hidden blood in the stool, detected as FOB, is often the first and only warning sign. There is also a potential future screening test still in development that looks for mutations in a specific gene (APC gene) that can be detected by analyzing the DNA from patients' stool samples.