Reducing Colonoscopies in Patients Without Significant Bowel Disease

Investigating people with bowel symptoms uses a test that detects traces of blood in the stools, the FIT test. There are many possible reasons for positive tests. A few people have cancer. However, most participants with symptoms don't have any serious bowel disease but have benign problems such as piles or irritable bowel syndrome (IBS). It is very difficult to diagnose on symptoms alone, those participants who have serious bowel disease and those who do not. After a positive test, people are invited for colonoscopy - a sort of articulated tube that is passed up the bowel. Most people invited for colonoscopy don't have cancer. Only about 5% of those with positive FIT tests have cancer. About 25% have other bowel diseases, but most have nothing serious wrong at all. So they have the inconvenience and discomfort of colonoscopy but don't get any benefit from it. The investigators want to try adding another test, the volatile organic compound (VOC) test, to see if the investigators can separate those with positive FIT tests who do have something wrong, from those who don't. The VOC test uses a urine sample. Using both tests might also be better for detecting cancer. FIT alone misses about 20%. So the investigators think that using both tests might not only be better for detecting cancer, but also might mean that a lot of people will avoid having to have colonoscopy. This study will recruit 1,819 participants with bowel symptoms from NHS trusts in the UK. They will provide stool samples for FIT and urine for VOC analysis. They will have colonoscopy to get a definite diagnosis. Then the investigators will look at their FIT and VOC test results to see if in future, people with both tests negative.