Beyond the Colonoscopy: Exploring Alternative Screening Methods for Colorectal Cancer
Colorectal cancer is a disease where the abnormal cells in the colon or rectum divide uncontrollably which ultimately forms a malignant tumour. Most colon cancer starts as an abnormal growth or lesion in the tissue which lines the inner surface of the colon or rectum. Lesions may appear as the raised polyps which can be attached to the inner surface of the colon or rectum with a stalk.
They may also grow along the surface without a stalk. Colorectal polyps are common in people above 50 years but most of them do not become cancer. However, adenoma polyp is more likely to become cancerous. Colorectal cancer is the third most common type of non-skin cancer for both men and women. It is important to treat colorectal cancer at an early stage by a colorectal cancer specialist doctor.
Also read: Colon Cancer Screening in Kolkata: Why Early Detection Saves Lives with Dr. Azhar Alam
Alternative Screening Methods for Colorectal Cancer
There are different screening methods other than colonoscopy which assists the doctors to find out the colorectal cancer before the symptoms start. Some of these tests allow adenomas and polyps to be identified and removed before they become cancerous. Some types of colorectal cancer screening methods may provide opportunities for cancer prevention along with early stage detection.
Stool Tests
Both polyps and colorectal cancers can bleed and stool tests can check for tiny amounts of blood in the stool which can’t be seen visually. The stool samples are collected by the patient using a particular kit and the samples are sent to the laboratory for testing. The US Food and Drug Association (FDA) has approved different types of stool tests for colorectal cancer screening. They are Guaiac fecal occult blood test (gFOBT), Fecal immunochemical test (FIT or iFOBT) and Multitarget stool DNA testing (sDNA-FIT).
Guaiac fecal occult blood test (gFOBT)
It uses a chemical to detect heme which is a component of the hemoglobin. gFOBT can identify heme in some types of food also. Therefore, it is recommended to avoid certain foods before this test. If gFOBT is the only type of colorectal cancer screening test performed, experts generally recommend testing every year or two.
Fecal immunochemical test (FIT or iFOBT)
This test uses antibodies to identify the hemoglobin protein. Dietary restrictions are not required for FIT. If FIT is the only type of colorectal cancer screening test performed, experts generally recommend testing every year or two.
Multitarget stool DNA testing (sDNA-FIT)
This testing detects hemoglobin along with specific DNA Biomarkers. The DNA comes from colon lining cells and rectum. They are shed and collected in stool as it passes through the large intestine and rectum. Experts generally suggest sDNA-FIT testing at least every 3 years.
Direct Visualization Tests
It is an important technique for the screening methods of colorectal cancer. The colorectal cancer specialist doctors use it for proper screening of the cancer. It includes pumping air into the colon through a tube which is inserted through the anus region into the rectum to expand the colon. The doctor can watch the lining more clearly. Sigmoidoscopy is one effective direct visualization test for the colorectal cancer screening process.
Sigmoidoscopy
The rectum and sigmoid colon are examined with the help of a sigmoidoscope. A sigmoidoscope is a flexible lighted tube with a lens for viewing and a tool for removing tissue. It is inserted through the anus into the rectum and sigmoid colon. During this process, the abnormal growth in the rectum and sigmoid colon can be removed for analysis. The lower colon is required to be cleared of stool before sigmoidoscopy. However, the preparation is not very extensive. People are not usually sedated for this test. The colorectal cancer specialists in Kolkata generally recommend screening sigmoidoscopy every 5 or 10 years for those people who possess an average risk. People who are screened with sigmoidoscopy may also be tested every few years with FIT.
Blood Based Test
This is a test for a molecular biomarker which is shed by colorectal cancer cells into the blood stream known as Epi proColon 2.0. It is FDA approved and to be implemented to screen adults for 50 years or above at an average risk for colorectal cancer. It is applicable for those who have been offered and possess a history of not completing colorectal cancer screening using a stool test or a direct visualization test. There is another blood based test for colorectal cancer screening. It is used for screening adults of age 45 or above who are at average risk for the disease. It analyzes plasma DNA for specific changes which includes the presence of harmful gene variants. However, these blood based tests are not yet included in the clinical guidelines for the first line colorectal cancer screening.
Other Methods
There are specific other methods which are sometimes used for colorectal cancer screening such as Double-contrast barium enema (DCBE) and Single-specimen gFOBT.
Double-contrast barium enema (DCBE)
It is another process for the visualization of the colon from outside of the body. In this process, a series of X-Ray images of the entire colon and rectum is taken after the patient is given an enema with a barium solution. It assists in the outlining of the entire colon and rectum on the images. The process is typically applied for the people who are unable to undergo standard colonoscopy such as having some specific risk for complications.
Single-specimen gFOBT
The medical professionals sometimes perform gFOBT on a stool sample which is collected during digital rectal examination as a part of the routine physical examination.
Conclusion
It is evident that different tests have different kinds of advantages and disadvantages. It is recommended to consult with the best colorectal cancer specialist before selecting any screening processes. However, there are some criterias which is considered before taking any decision about screening methods. These criterias are age, medical history, family history and general health and potential harmful effects of the test. Also there are preparation needed, requirement of sedation, followup care required after the test, convenience and the effective cost of the test. If you are from or nearby Kolkata, Dr. Azhar Alam is one of the best colorectal cancer specialist doctors in Kolkata. It is recommended to consult with him before taking any decision on screening methods for colorectal cancer.
