DNA Test May Aid PCa Detection

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CHICAGO—DNA blood tests under development may provide a more accurate way to detect prostate and breast cancer, according to findings presented at the American Society of Clinical Oncology annual meeting.

The findings, from a study of 575 subjects, showed that the tests have a 92% sensitivity and 100% specificity for detecting both malignancies.

By comparison, PSA tests for prostate cancer have demonstrated an 85% sensitivity and 25%-35% specificity and mammography screening has a 75% sensitivity and 92.3% specificity for detecting breast cancer, with lower figures for some populations such as younger women, according to investigators.

The tests, which are being developed by Chronix Biomedical Company of San Jose, Calif., identify disease-specific genetic fingerprints based on DNA fragments released into the bloodstream by damaged and apoptotic cells.

DNA from apoptotic cells originates from a limited number of regions or “hotspots” on the genome specific to each cancer. Thirty-two unique hotspots are associated with prostate cancer and 29 are associated with breast cancer.

Among the 575 individuals in this study, 197 had prostate cancer (Gleason score 3-10/Stage II-IV) and 178 had early-stage (stages 1 and 2) invasive breast cancer; 200 subjects were healthy controls.

Lead investigator Ekkehard Schütz, MD, PhD, Vice-President of Research at Chronix, said a new assay for prostate cancer could greatly improve the detection and management of the disease.  “We definitely need something better than PSA,” said Dr. Schütz, adding that PSA screening falsely alerts too many men that they may have prostate cancer.

If the data are confirmed in larger studies, the researchers said, these assays have the potential to reduce the current rate of false positive and false negative test results that contribute to poorer patient outcomes and higher health care costs.

“Hopefully, it [the prostate cancer test] will be better than PSA,” said investigator William Mitchell, MD, PhD, Professor of Pathology at Vanderbilt University in Nashville, Tenn., and an independent member of the Chronix Board of Directors. “We still don't know what will happen in men who have prostatic hypertrophy, and we still don't know what will happen in prostatitis.”

Chronix is launching its investigational use only testing service to the medical oncology and pharmaceutical research communities, Dr. Schütz said.

The initial focus is to provide researchers conducting clinical trials with an affordable and reliable tool to help advance their biomarker programs for monitoring cancer recurrence. These new assays may be able to provide rapid feedback on potential efficacy of products under investigation, he said, noting that this could significantly reduce the time needed to obtain medically useful results.

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