People with a family background of colon cancer and additionally individuals with symptoms are at increased risk of getting colon cancer. The main procedure employed by physicians to test for colon cancer if an inidividual has a family history or is complaining of a symptom, such as blood in the stool, is the colonoscopy. With this method doctors are able to see the inside of the colon and look for abnormal (and possibly cancerous) growths. In addition to testing people who are at an increased risk level, physicians also typically advocate that asymptomatic people who are 50 or older undergo routine screening in order to discover any cancer that may be developing in the colon before it reaches an advanced stage.
In case the doctor conducting the colonoscopy is unable to look at the full span of the colon it is feasible that there might be cancer present in the sections that were not examined. Among the reasons why a doctor might not finish the colonoscopy is inadequate prior preparation resulting in inadequate visualization or the presence of an obstruction which makes it impossible to pass the scope beyond the area of the obstruction. When situations like these occur the doctor should tell the patient and recommend that the individual either undergo an alternative procedure or a repeat colonoscopy. A failure to do so may lead to a missed cancer which can grow and progress to an advanced stage before it is detected.