Blood test to screen cancer risk

Researchers have found that a simple blood test seems to identify people at high risk of developing colorectal cancer . They discovered that patients with colorectal cancer or pre-cancerous polyps showed an unusual genetic change that could easily be detected in their blood.According to the scientists at the John Hopkins University in Baltimore, a subtle molecular change that switches on a usually inactive gene has been linked to an increased risk of developing colon cancer. The molecular change can be detected in a blood test and could one day be used routinely to predict a patient's chances of developing colon cancer. They analysed blood samples from 172 patients who had colonoscopies. The researchers were searching for chemical evidence of a process called "loss of imprinting," or LOI, in the insulin-like growth factor, or IGF2 gene. Two copies of this gene are inherited; one from each parent, but normally only the copy inherited from the father makes the growth factor. Loss of imprinting is a valid marker for colon cancer. Based on the analysis of these patients, the team found that those with a family history of colon cancer were five times more likely to have the LOI marker. Patients who had polyps, an early stage of cancer development, were three times more likely to have LOI, while patients with a personal history of colon cancer were 22 times more likely to have LOI. Among healthy patients with no family history of cancer, about one in 10 had the LOI marker. The researchers will have to look at blood samples from many more randomly selected patients and follow them for several years. It may be five years before the test would be ready for general use.

Colon cancer is one of most deadly cancer but is considered one of the most curable of the serious cancers because its early stages can be detected by colonoscopy. Studies have, however shown that many patients dread and avoid the test, which involves drinking several quarts of a solution to clean the colon, followed by being probed with a medical instrument. A blood test that accurately defines a patient's colon cancer risk could reduce the need for such invasive procedures. This finding has the potential to be an important advance in the detection of colon cancers. It would be very desirable to have a simple way to test patients through their blood to predict their risk of cancer in the colon and in other organs as well.

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