Different Types of Screening Tests for Colorectal Cancer
Colorectal Cancer Screening
Screening tests for colorectal cancer are used to detect the presence of cancer, polyps, lesions that are non-polypoid, and other abnormal conditions in the colorectal area. The advantage of these tests is that the disease can be diagnosed early and treatment can be effective in the early stages. If non-malignant polyps are detected, they can be surgically removed in order to prevent the future development of a colorectal malignancy. Scientific evaluation of the effectiveness of screening tests for this cancer is still underway. Each test also offers its own advantages and disadvantages which help to decide the choice of test in a particular case.
Fecal Occult Blood Test
This is among the most common screening tests for colorectal cancer. This test examines the presence of blood in the stool or fecal material. It is normally recommended that people in the age group of 50 to 80 should undergo this test every one or two years. The test can help in early detection of colorectal cancer.
The advantages of this test are that it does not require colon cleansing, does not result in damage to the colon lining, the samples can be collected at home and the cost of this test is relatively low. The limitation of the test is that it cannot detect most of the polyps and a few types of cancer. The test may sometimes indicate false alarm, and may require additional colonoscopy to determine the presence of the disease.
Sigmoidoscopy for Colorectal Cancer
This screening test uses a sigmoidoscope to examine the condition of the lower colon and rectum. This test can help to identify malignant or pre-malignancy growth in the lower colon and rectum, which can be surgically removed and sent for biopsy. Periodic testing after the age of 50 can help in early detection of colorectal cancer.
The advantage of this test is that it can be performed efficiently with minimal complications and discomfort. Sometimes the removal of polyps or the biopsy may be conducted during the course of the test only. The test requires cleansing of the colon, but not as extensively as in case of colonoscopy. The limitation of the test is that it does not allow an examination of the upper portion of the colon for the presence of polyps. There is also a minor risk of damage to the colon lining during the test.
Colonoscopy
This is an extensive screening procedure that involves the use of a lighted device known as colonoscope. The test allows examination of the complete colon and rectum area. Any pre-malignancy or malignant growths can be detected in the colon or rectum area and removed and biopsied. The test usually involves sedation and requires a complete colon cleansing before it can be performed.
The benefit with this test is that it enables a full examination of the colon and rectum. Polyps or other abnormal tissue growths can be removed during the course of the test and biopsied if required. The limitation of the test is that it may not be able to detect very small sized polyps or non-polypoid lesions. However, it still remains one of the most effective screening tests today for detection of colorectal cancer.
Double Contrast Barium Enema Test
This test involves taking X-ray images of the colon and rectum area after administering an enema to the patient using a barium solution and passing air through the colon. The X-ray images can show the colon outline quite clearly when the barium and air is passed through it.
The advantage of this test is that it allows for a full view of the colorectal area. The test does not require sedating the patient, and complications are minimal. The limitation is that the test may fail to identify very small sized polyps and cancers. Extensive cleansing of colon is also required prior to this screening. A biopsy or removal of polyps cannot be undertaken during the course of this test.
References
https://www.cancer.gov/cancertopics/factsheet/Detection/colorectal-screening
https://familydoctor.org/online/famdocen/home/common/cancer/risk/556.html
