Doctors say if the slow-progressing disease is caught early enough using screening methods, there is a 95 percent survival rate. The American Cancer Society currently advises those at average risk get screened for colon cancer starting at age 50 and those at high-risk, such as those with a family history, begin sooner. The group's recommendations include an annual test for blood in the stools, called a fecal occult blood test, which can indicate cancer, as well as a flexible sigmoidoscopy every five years, or a barium enema and subsequent X-ray of the colon every five to 10 years, or a colonoscopy every 10 years. A sigmoidoscopy uses a tube to inspect the lower colon in a doctor's office, while a colonoscopy requires bowel preparation and hospitalization, done on an outpatient basis, but checks the entire colon. Patients found to have abnormal stool samples will then be given the full colonoscopy, which can remove any cancers or pre-cancerous polyps instantly.
Colonoscopes contain small cutting devices which can be threaded through the tube to remove growths.
The new DNA-based test is similar to the fecal occult blood test in that patients or doctors simply take a swab of a stool sample for diagnosis, without having to undergo the more invasive tests. But the blood test only has a 50 percent chance of catching advanced cancers in a single screening and will miss the majority of earlier polyps. The test only detects whether blood is oozing from an advanced cancerous cell, but the presence of blood could also be a result of other non-cancerous conditions, such as a benign polyp or an abnormal blood vessel. The new DNA test instead collects cells shed from the lining of the colon and amplifies the genetic material, looking for indications of mutations at those earlier stages of cancer. The DNA test currently looks at seven specific genes previously identified by researchers as being identified with colon cancer.