IS IT CANCER
New Methylation Marker Shows Promise
The doctor suspects cancer-because a man's PSA is higher than it should be, or his digital rectal exam found something abnormal-but the biopsy didn't find any cancer. What happens next? Most likely, another biopsy-at which point, says urologist Mark Gonzalgo, M.D., Ph.D., as many as 36 percent of these men will be found to have cancer.
Here's where a new biomarker, which he and colleagues are working to develop, would be of great help. For one thing, Gonzalgo notes, it could distinguish between cancer and BPH, benign enlargement of the prostate. "Methylation of GSTP1 has been detected in the urine and prostatic fluid of men with prostate cancer, but not in men with BPH, or in normal prostate tissue."
Thus, instead of undergoing another biopsy and months of uncertainty, these men could take a simple urine test. In a recent study, published in the journal Clinical Cancer Research, Gonzalgo, Christian Pavlovich, and William Nelson analyzed urine specimens of men who underwent prostate biopsies. They found methylation of GSTP1 in about half of the men-in 33 percent of men who had negative biopsies, and in 67 percent of men with either suspicious-looking cells or PIN. "This suggests that there was hidden cancer," says Gonzalgo, "and that the biopsies had a false negative result." He believes that this test could help doctors decide whether a man is at high or low risk for cancer, and whether he needs an early repeat biopsy.