2 Colorectal cancerColorectal cancer, also known as colon cancer, rectal cancer, is a cancer from uncontrolled cell growth in the colon or rectum (parts of the large intestine), or in the appendix]Most colorectal cancer occurs due to lifestyle and increasing age with only a minority of cases associated with underlying genetic disorders. It typically starts in the lining of the bowel and if left untreated, can grow into the muscle layers underneath, and then through the bowel wall.Screening is effective at decreasing the chance of dying from colorectal cancer and is recommended starting at the age of 50 and continuing until a person is 75 years old. Localized bowel cancer is usually diagnosed through colonoscopy.Cancers that are confined within the wall of the colon are often curable with surgery while cancer that has spread widely around the body is usually not curable and management then focuses on extending the person's life via chemotherapy and improving quality of life.Colorectal cancer is the third most commonly diagnosed cancer in the world, but it is more common in developed countries
3 The symptoms and signsThe symptoms and signs of colorectal cancer depend onthe location of tumor in the bowel.whether it has spread elsewhere in the body (metastasis).The classic warning signs include:worsening constipation.blood in the stool.decrease in stool caliberloss of appetite.loss of weight.nausea or vomiting
5 Colonic PolypsA polyp is an extra piece of tissue that grows inside your body. Colonic polyps grow in the large intestine, or colon. Most polyps are not dangerous. However, some polyps may turn into cancer or already be cancer. To be safe, doctors remove polyps and test them. Polyps can be removed when a doctor examines the inside of the large intestine during a colonoscopy.
6 Symptoms and Risk factors Anyone can get polyps, but certain people are more likely than others. You may have a greater chance of getting polyps if youAre over age 50Have had polyps beforeHave a family member with polypsHave a family history of colon cancerMost colon polyps do not cause symptoms. If you have symptoms, they may include blood on your underwear or on toilet paper after a bowel movement, blood in your stool, or constipation or diarrhea lasting more than a week.
7 DiagnosisDiagnosis of colorectal cancer is via tumor biopsy typically done during colonoscopy or sigmoidoscopy, depending on the location of the lesion. The extent of the disease is then usually determined by a CT scan of the chest, abdomen and pelvis. There are other potential imaging test such as PET and MRI which may be used in certain cases.The three main screening tests are fecal occult blood testing, flexible sigmoidoscopy and colonoscopy.Virtual colonoscopy via a CT scan appears as good as standard colonoscopy for detecting cancers and large adenomas but is expensive, associated with radiation exposure, and cannot remove any detected abnormal growths like standard colonoscopy can.
8 ColonoscopyA colonoscopy is an exam that views the inside of the colon (large intestine) and rectum, using tool called a colonoscope.The colonoscope has a small camera attached to a flexible tube that can reach the length of the colon.How the Test is PerformedYou will usually be given medicine into a vein to help you relax. You should not feel any discomfort. You will be awake during the test and may even be able to speak, but you probably will not remember anything.You will lie on your left side with your knees drawn up toward your chest. The colonoscope is inserted through the anus. It is gently moved into the beginning of the large bowel and slowly advanced as far as the lowest part of the small intestine.Air will be inserted through the scope to provide a better view. Suction may be used to remove fluid or stool.The health care provider gets a better view as the colonoscope is moved back out. Therefore, a more careful exam is done while the scope is being pulled back. The doctor may take tissue samples with tiny biopsy forceps inserted through the scope. Polyps may be removed with snares, and images may be taken.
9 Why the Test is Performed Colonoscopy may be done for the following reasons:Abdominal pain, changes in bowel movements, or weight lossAbnormal changes (such as polyps) found on sigmoidoscopy or x-ray tests (CT scan or barium enema)Anemia due to low iron (usually when no other cause has been found)Blood in the stool, or black, tarry stoolsFollow-up of a past finding, such as polyps or colon cancerInflammatory bowel disease (ulcerative colitis and Crohn's disease) Screening for colorectal cancer
12 Virtual colonoscopyVirtual colonoscopy (VC, also called CT Colonography) is a medical imaging procedure which uses x-rays and computers to produce two- and three- dimensional images of the colon (large intestine) and display them on a screen.[The procedure is used to diagnose colon and bowel disease, including polyps, diverticulosis and cancer. VC is performed via computed tomography (CT), sometimes called a CAT scan, or with magnetic resonance imaging (MRI). A virtual colonoscopy can provide 3D reconstructed endoluminal views of the bowel.
14 Virtual colonoscopyWhile preparations for VC vary, the patient will usually be asked to take laxatives or other oral agents at home the day before the procedure to clear stool from the colon'. This allows the user (usually a consultant radiologist), viewing the 3D images to effectively subtract the left over faeces, which may otherwise give false positive results.VC takes place in the radiology department of a hospital or medical center. The examination takes about 10 minutes and does not require sedatives.
15 Virtual colonoscopy During the procedure: The patient is placed in a supine position on the examination tableThe patient may be given a dosage of Butylscopolamine intravenously to minimize muscle activity in the area.A thin tube is inserted into the rectum, so that air can be pumped through the tube in order to inflate the colon for better viewing.The table moves through the scanner to produce a series of two-dimensional cross-sections along the length of the colon. A computer program puts these images together to create a three- dimensional picture that can be viewed on the video screen.The patient is asked to hold his/her breath during the scan to avoid distortion on the images.The scan is then repeated with the patient lying in a prone position.After the examination, the images produced by the scanner must be processed into a 3D image, +/- a fly through (a cine program which allows the user move through the bowel as if performing a normal colonoscopy). A radiologist evaluates the results to identify any abnormalities