Blood Test Accurately Detects Biomolecular Markers of Bladder Cancer

A blood test can accurately detect biomolecular markers of bladder cancer that was caused by exposure to carcinogens.

The test measures a pattern of methylation--a chemical alteration to DNA that affects the genes expressed in cells, and is associated with bladder cancer. Methylation is affected by exposures in the environment, such as cigarette smoke and industrial pollutants and many scientists believe that abnormal patterns of it in the body could be indicators of an increased likelihood of disease.

A team of scientists at Brown University (Providence, RI, USA) studied the blood of 112 people who had bladder cancer and 118 who did not. This provided the pattern of methylation to look for in immune system cells in the blood. Then, under blind conditions, they applied that test to the blood of a similar number of people who either had the cancer or did not, and made their predictions.

They found that they could determine who had the cancer and who did not, based solely on the methylation pattern they observed. Controlling for the exposure to known risk factors such as smoking, they found that people with the methylation pattern were 5.2 times more likely to have bladder cancer than people who did not have the pattern.

The scientists could not be sure whether the methylation markers in their immune system cells were predictors of cancer (i.e., they were present before the cancer began growing, as the team's hypothesis suggests) or simply indicated that the cancer was already there (i.e., they are a consequence of the cancer).

"What we might be measuring is an accumulated barometer of your life of exposures that then put you at risk," said leader of the study, Carmen Marsit, assistant professor of medical science in the department of pathology and laboratory medicine at the Warren Alpert School of Medicine at Brown University. "Will you ever really figure out if eating something when you were 12 gave you cancer? Instead we can use these kinds of markers as an integrated measure of your exposure history throughout your life."

The study proved that the cancer is associated with a methylation pattern that can readily be detected in blood. For cancers that are buried deep in the body and are therefore hard to detect, such as bladder cancer, a minimally invasive test that provides either prediction or early detection of cancer could make a big difference in improving a patient's prognosis, Prof. Marsit added.

The study was published online on Feb. 22, 2011 in the Journal of Clinical Oncology.

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