Study: Simple Blood Test May Predict Colorectal Cancer Risk

A simple blood test for an unusual genetic change may identify people at risk of colorectal cancer, according to Johns Hopkins University researchers.

While the blood test does not detect colorectal cancer, it appears to identify people with a tendency to develop the disease who would benefit from an early screening test.

Researchers said this test thus might ultimately reduce the need for everyone over 50 to have colonoscopies, an uncomfortable colon and rectal exam can detect precancerous growths before they become life threatening.

The DNA-based blood test looks for a change called "loss of imprinting" in the gene for a protein called insulin-like growth factor II (IGF2). "Loss of imprinting" means that an extra copy of a particular gene that promotes cell growth is turned on.

"When you have loss of imprinting of the IGF2 gene in colon cancer, the mother's gene copy gets turned on by mistake and the cell gets a double dose of abnormal cell growth," said Johns Hopkins reneticist Andrew Feinberg.

Feinberg and his colleagues used the blood test to look for the alteration in 172 people who were undergoing screening colonoscopies.

They reported in the journal Science that people with a family history of the colorectal cancer were about five times more likely to have lost imprinting in the IGF2 gene, people with a history of precancerous colorectal growths called adenomas were three times more likely to have loss of imprinting.

They also found that loss of imprinting was almost 22 times more common in patients with a personal history of colorectal cancer were nearly 22 times more likely to have these markers.

Feinberg emphasised that the present test is only useful for research purposes, and said "more efficient tests will take several more years to develop."

Other sources: Science