Colorectal Cancer Screening

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06/22/23

Developed and produced by http://www.MechanismsinMedicine.com
Animation description: Screening programs aim to identify individuals with cancers at an earlier stage and allow for treatment before growth and spread has occurred. It also allows for detection of pre-cancerous growths such as polyps before the cancer has even developed. Several screening techniques for colon cancer have been used.
As cancers grow they may bleed. Small amounts of blood are not necessarily visible within the stool. Testing stool samples for occult blood may indicate the presence of a cancer within the colon. Several trials have shown benefit from the use of this test as a screening tool.
This test should be part of a regular exam however it will only detect cancers within the reach of the examining finger [cancers of the mid and lower rectum]
Modern scopes have had several improvements. They are thinner and more flexible with better fibre optics allowing sharper images. In addition the instruments allow the use of additional devices for a variety of functions such as snares for polypectomies, forceps for biopsies and other injection devices.
Flexible sigmoidoscopes are 60 cm long and are able to detect about 65% of all polyps. Upon the discovery of an adenoma, a colonoscopy is usually required to evaluate the proximal bowel.
Case control studies have shown benefit in terms of reduced colon cancer mortality and incidence however they only evaluate the distal end of the colon.
A colonoscopy is the gold standard in terms of screening. A scope enters the rectum and is extended through the entire colon.
This test will identify almost all cancers and most pre-malignant polyps. It also allows for the removal of smaller growths. This test only has to be repeated every 5-10 years if no polyps are present.
Virtual colonoscopy is a new technique that uses computed tomographic or magnetic resonance images to produce computer-generated images of the colon.
Patients still require bowel prep and have air insufflated into their colons. In experienced hands, this test is as good as colonoscopy in detecting cancers and larger polyps.