Like many cancers, colorectal cancer has the best prognosis when caught early. However, early instances of colorectal cancer don’t cause symptoms, which means people must undergo medical testing to detect the issue early on. In this case, doctors can use one or more of the following screening tests to ensure a timely and accurate diagnosis.
Colorectal cancer begins with polyps inside the large intestine. These polyps can release blood into the stool, and a faecal occult blood test can detect possible issues when the amount of blood released is still relatively minor. This screening test is also called a stool guaiac test and should take place on a yearly basis once a person reaches the age of 45.
Similar to faecal occult blood test, a stool DNA test looks for abnormal DNA in cells in addition to the presence of blood. It is recommended that this test takes place once every three years. In the event of abnormal results, doctors will order a follow-up physical exam.
A colonoscopy is a physical examination of the colon and rectum. This exam entails using a colonoscope, which is inserted into the anus to extract tissue samples and perform a visual assessment via an attached camera. Patients can also undergo virtual colonoscopies, which do not require use of the colonoscope, which many people find uncomfortable. Colonoscopies usually take place every five to ten years.
A sigmoidoscope is a smaller instrument that assesses the lowermost portion of the colon and rectum. While sigmoidoscopies are not as invasive as colonoscopies, and associated with less discomfort as a result, this screening test may fail to detect polyps situated in the upper area of the colon. Doctors may recommend this test once every five years.