Colorectal Cancer Screening

Screening test helps in the detection of polyps that are the outgrowths before they turn cancerous. This helps in preventing colorectal cancer moreover early detection leads to effective treatment.

Screening test 

A screening test is performed for the detection of a disease when the symptoms of that disease are not present while a diagnostic test is the one that is performed post detection of a symptom.

Colorectal cancers are most of the time developed from the precancerous polyps, polys or outgrowths that are formed in the colon or rectum.

These screening tests find the polyps and remove or eliminate them from the colon or rectum before they turn out to be cancerous.

Screening recommendations

It is advised that an individual should start regular screening after the age of 45. This is the recommendation of the U.S preventive task force, moreover, it also recommends that adults between the age of 45 to 75 should talk to doctors regarding the screening process. 

The task force has recommended various strategies like the stool test, flexible sigmoidoscopy, colonoscopy, and CT colonography (virtual colonoscopy).

Colorectal cancer screening test

The US preventive services task force (task force) recommends several screening tests to find the polyps that cause colorectal cancer. If the result is positive or abnormal in some screening test then the person should go for a complete screening process. The various screening tests are discussed below as follows -:

Stool tests

• In this test the guaiac-based faecal occult blood test (gfobt) is done which uses the chemical guaiac for detecting blood in the stool.  In this test, a test kit is provided to the individual and the stool sample is submitted to the lab for testing blood in the stool. This test is conducted once a year.

• The faecal immunochemical test (fit) -this test uses antibodies to detect the presence of blood in the stool and is also conducted once a year 
• The fit-DNA test (faecal immunochemical test) – this test is also known as the stool DNA test. This test looks for alerted DNA in the stool. For those tests, the entire bowel movement is sent to the lab for a testing post that it is checked for the altered DNA  and the presence of blood in the cell. This test is conducted once every three years. 

Flexible sigmoidoscopy

 In this test, the doctor puts a light, slender tube into the rectum for checking for polyps or cancer in the rectum and the lower third colon. This test is conducted every 5 years or 10 years along with the faecal immunoglobulin test (fit). 

Colonoscopy

It is similar to flexible sigmoidoscopy in the way that it also uses a thin, flexible tube to detect the polyps inside the rectum but the point of contrast is that it is used for the entire colon, not just the third colon. It is a follow-up test that is performed if any of the screening tests is found to be positive. During this test, most of the polyps are removed. This test is performed every ten years for those with a decreased risk of cancer.

CT colonography (virtual colonoscopy)

Computed tomography (CT) colonography is a process that uses x rays to produce an image of the entire colon and that is used by the doctors to produce the entire image of the colon, which provides an extra edge to the treatment. It is also known as a virtual colonoscopy. It is conducted every five years.

Selecting a screening test

• The criteria for selecting a particular test depend on certain factors including – the preference of the individual, the medical condition., family history of any colorectal cancer or polyps if the person suffers from any genetic syndrome such as familial adenomatous polyposis (fap). 
• Further, the final decision should be based on considering advantages and disadvantages and post consultation with the doctor.

Conclusion

Colorectal cancer in this term the word Colour is for colon and the word rectal for rectum both of which are the parts of the large intestine. Colorectal cancer occurs due to abnormal outgrowths of polyps in this region of the human body. Various screening tests can be performed for the diagnosis of colorectal cancer like the stool test which is conducted via guaiac-based faecal occult blood test (gfobt), faecal immunochemical test (fit), fit-DNA test (faecal immunochemical test); flexible sigmoidoscopy wherein a thin, flexible tube is put in the rectum and third lower of the colon to detect for the polyps; colonoscopy- in this test the same thin, flexible tube is used and is put in the rectum and the entire colon; a virtual colonoscopy is another test wherein the x-rays are used along with the computers to get an image of the rectum. These images are then analysed by the doctor to look for cancer-causing polyps. The selection of the screening test depends on the preference of the individual, resources, doctor’s recommendation, and family history of any genetic disorder.