Colon cancer is a disease characterized by the uncontrolled division of abnormal cells in the colon and the formation of tumors from these cells. Despite the presence of polyps in the human large intestine, presentation of colon cancer symptoms at an early stage is very low. In some cases, it may not even manifest symptoms. Today, colon cancer is the second leading malignancy in the United States and the fourth worldwide. The combination of these facts gives rise to the importance of colon screening methods aimed at determining early stages of colon cancer.
There are a number of screening methods available for colon cancer detection. These tests are done alone or in combination with other tests in order to distinguish colon cancer from other intestinal diseases. Hereunder is a list of these screening and detection procedures.
Digital Rectal Examination
A routine part of physical examination, digital rectal examination (DRE) examines the lower portion of the rectum for tumor and polyp growth. This test is done using a lubricated gloved finger inserted inside the rectum to feel for anomalous growths. This test is also capable in ascertaining prostate cancer in men.
Fecal Occult Blood Test (FOBT)
The American Cancer Society recommends FOBT to be done yearly in combination with sigmoidoscopy. FOBT is statistically noted as being 24% effective in finding colorectal cancer by itself. There are currently two types of fecal occult blood test, these are the Guaiac FOBT and the Immunochemical FOBT. The Guaiac FOBT utilizes the chemical, guaiac, to detect the presence blood protein hemoglobin in fecal samples by checking for traces of Heme. Heme is an iron-containing component of hemoglobin. Immunochemical FOBT uses antibodies to check stools for human hemoglobin. According to studies, FOBT when performed annually reduces colorectal deaths by about 15 – 35%.
Sigmoidoscopy is a test wherein a lighted instrument, the sigmoidoscope, is inserted into the rectum and lower colon to examine the area. Precancerous, cancerous and other abnormal growths can be detected during this test, and these growths can be removed and biopsied. Statistics show that when done in conjunction with FOBT, the sigmoidoscopy helps in detecting about 76% of colon tumor growths among individuals in the 50s-80s age range.
A colonoscope is a lighted instrument used to examine the colon and rectal area for abnormal growths. During a colonoscopy, abnormal polyps or growths can be traced, removed and biopsied. Colonoscopy can examine areas missed by a sigmoidoscope mainly due to its longer reach. Before colonscopy is performed a thorough cleansing of the colon is carried out and patients are sedated.
Double Contract Barium Enema (DCBE)
In DCBE, air is introduced into the colon and the patient is given an enema filled with barium solution to help outline the colon for an array of x-rays. In conjunction with colonoscopy, DCBE helps in detecting about 30-50 percent of colorectal cancer cases. However, DCBE may miss smaller polyps according to research.
Computerized Tomographic Colonoscopy
As called Virtual Colonoscopy, the test is accomplished with the use of a special x-ray equipment to generate photographs of the colon and rectum at different angles. These photographs are then assembled by a computer to produces an image detailing the large intestine and showing polyp growth and other abnormalities. Like standard colonoscopy, it is necessary to perform a thorough cleansing of the colon. However, since this test is less invasive, it is less discomforting and does not require sedation.
Despite the presence of these tests, it was reported that about 44% of adults within the 50s-80s age group have undergone routine screening raising colorectal cancer incidence. Let us not be afraid to undergo cancer screening, we must realize that early detection is tantamount to survival from cancer.
For further reading about colon cancer detection, treatments, and symptoms read some of material that I have published.