The American Cancer Society advocates regular and early screening for cancer.
Screening increases the chances of detecting certain cancers when they are most likely to be curable. Colorectal or colon cancer is one of those. The screening procedure for this disease is a colonoscopy, which is usually done by a colon-rectal surgeon or a gastroenterologist.
Using a colonoscope – a flexible hollow tube with a tiny camera on the end – the physician looks closely at the inside of the colon and rectum for polyps, small growths that can develop into cancer. The patient is sedated during the procedure, which generally lasts about 30 minutes.
In order to get a proper, clear reading, the colon must be emptied and as clean as possible. (This is the step most patients dread.) Preparation generally requires a powerful laxative and/or an enema. The day before the colonoscopy, the patient takes a laxative preparation such as Picosalax, Bisacodyl, phospho soda, sodium picosulfate or sodium phosphate and/or magnesium citrate. A whole-bowel irrigation is performed using a solution of polyethylene glycol and electrolytes. The polyethylene glycol powder is dissolved into a clear liquid, such as a sports drink containing electrolytes. The patient is advised to stay close to a toilet and continue to hydrate.
Complications from a colonoscopy are rare but possible. These include bleeding and puncture of the colon. When a polyp is found, it is usually removed by a cold-knife snare procedure called a polypectomy; if the polyp is abnormal, it might be sent for a biopsy to determine whether it is precancerous.
The median recommended age for an initial colonoscopy is 50 years. If there is a first-line relative with colon cancer, screening for family members should be done 10 years earlier than the age of their diagnosis. Subsequent screening depends on the results,as well as the individual’s risk for colon cancer. Colonoscopy is not recommended for patients with ulcerative colitis or Crohn’s disease.
The five-year survival among those whose colon cancer is detected early is 90 percent. Early on, colorectal cancer doesn’t usually have symptoms. In most cases, by the time symptoms such as rectal bleeding occur, the cancer is advanced and more difficult to treat. Other types of colon screening include sigmoidoscopy (which examines only the lower 2 feet of the colon), double-contrast barium enemas and virtual colonoscopy, which uses 2D and 3D imagery from computed tomography (CT) scans or from nuclear magnetic resonance (MR) scans.