TEST TO REDUCE REPEATED PROSTATE BIOPSIES

In men with previous histopathologically negative findings, the epigenetic ConfirmMDx (MDxHealth) assay for prostate cancer can lead to a 10-fold reduction in repeat biopsies, 2 new studies show.

Both confirm the utility of epigenetic profiling in helping to distinguish patients who have a true negative biopsy from those at risk for occult cancer, according to the researchers.

The commercially available assay assesses methylation markers of prostate cancer (GSTP1, APC, and RASSF1) to distinguish histologically benign biopsy cores from patients diagnosed with no cancer, low-volume cancer (a Gleason score of 6), or higher-volume cancer (a Gleason score of 7).

One of the studies, a clinical utility field study in which the assay was tested by practicing urologists working in community settings, was published in the May issue of American Health & Drug Benefits.

Assay a "Piece of the Puzzle"

Until ConfirmMDx, "we had no reliable tool to tell us whether or not a patient should have another biopsy," said investigator Jeffrey D. Small, MD, a practicing urologist from the Yale–New Haven Health System at Bridgeport Hospital in Connecticut.

"Although the test isn't perfect, it gives us something that we didn't have before," he told Medscape Medical News.

With the assay, changes in DNA methylation that occur during oncogenesis can be assessed in the biopsy tissue, indicating whether a repeat biopsy is necessary. "I use the test as a piece of the puzzle; it is not the whole answer. There are other things that would determine each individual's risk," Dr. Small explained.

"The goal is to minimize the number of biopsies in patients who otherwise might have routinely undergone repeat biopsy. In this era of managed care and Accountable Care Organizations, where we are looking at costs, if we have a test that can minimize the number of repeat biopsies without missing cancer, then everybody wins," he said.

"I now use the test routinely in my practice," he added.

The ConfirmMDx assay has a negative predictive value of 90%; however, the positive predictive value is only 28%.

In their study, Dr. Small and his colleagues assessed the impact of a negative ConfirmMDx result on a urologist's decision to conduct a repeat prostate biopsy.

They evaluated urologists from 5 practices that had ordered ConfirmMDx on at least 40 patients with previous biopsies negative for cancer during the previous 18 months.

The analysis involved 138 patients from these practices. Mean age in the cohort was 63 years, and median serum prostate-specific antigen (PSA) level was 4.7 ng/mL.

There was 10-fold reduction in repeat biopsies with the assay. Only 6 of the patients (4.3%) with a negative result underwent repeat biopsy. Previous research has shown the rate of repeat prostate biopsy to be above 40.0% (BJU Int. 2007;99:775-779).

More Validation From DOCUMENT

The second study, the multicenter Detection of Cancer Using Methylated Events in Negative Tissue (DOCUMENT) validation study, was published online April 16 in the Journal of Urology.