Colorectal cancer, which affects the colon (also known as the large intestine or rectum) is the third most common cancer in the world. Symptoms of colorectal cancer include changes in bowel habits, rectal bleeding, abdominal discomfort, and unexplained weight loss. It is recommended that people begin getting colon cancer screenings at age 50. The “immunological Fecal Occult Blood test” (iFOB) is one such method of screening that detects the presence of blood in patients’ stools. A positive result indicates that further testing is needed to confirm the presence of colon cancer.
The tests used to confirm the presence of colorectal cancer include colonoscopy and CT colonography. A colonoscopy involves using a long, flexible tube attached to a video camera to view the entire colon and rectum. Any potentially cancerous areas are further examined by taking tissue samples and analyzing them. The CT colonography combines images from CT scans to produce a picture of the inside of the colon, which can then be inspected for suspicious areas.
Image Source: Tannis Toohey
Although the iFOB test is the best test currently available, it doesn’t detect all types of colon cancer. Recently, however, scientists from the research institute VIB and the University of Leaven along with other European oncology centers, have made progress in developing a new diagnostic screening test for colorectal cancer. Instead of the iFOB test, the researchers propose a simple blood test to detect the cancer.
Once the body is affected by cancer, the immune system responds by trying to remove the cancerous cells. The peripheral blood monocyte, a type of white blood cell, plays a big role in this process. Colorectal cancer cells secrete substances which cause an immediate response by the peripheral blood monocytes. The researchers have identified the genes that are activated in the monocytes as a result of the secretions. The identified genes can be used as bio-markers in a diagnostic blood test for colorectal cancer. Currently, the researchers have a set of 23 genes used in the diagnostic test but are trying to reduce the number to develop a test using the smallest number of biomarkers possible, as 23 genes is still too many to include in a standard diagnostic test.
Feature Image Source: October 2, 2011 by Flood G.