"One of the problems with testing for levels of PSA as an indicator of prostate cancer is that PSA levels often fluctuate, making it difficult to know for certain whether a man has prostate cancer without performing multiple biopsies over time," said Robert Getzenberg, Ph.D., senior author and professor of urology, pathology and pharmacology at the University of Pittsburgh School of Medicine. "By testing for EPCA in men with high levels of PSA, we may be able to detect the presence of prostate cancer earlier, before it is discoverable by biopsy, saving patients the fear and stress of repeat procedures and enabling us to treat the disease sooner."
Dr. Getzenberg explained that EPCA is a marker protein that indicates the earliest changes that occur in cells during the development of cancer.
In the study, Dr. Getzenberg, also co-director of the Prostate and Urologic Cancer Program at the University of Pittsburgh Cancer Institute, and colleagues developed antibodies against EPCA to detect its presence in tissue. They compared 27 non-diseased control tissue samples to 29 tissue samples from patients with prostate cancer who had initial negative biopsies. They found that the samples from the negative biopsies of those patients who were eventually diagnosed with prostate cancer expressed EPCA and that EPCA was not expressed in tissue samples from individuals without disease. They also found that EPCA was not only expressed in the tumor, but throughout the prostate in men with prostate cancer indicating its usefulness as a prognostic marker for prostate cancer.
A multi-center study is currently underway to further assess the usefulness of EPCA and its possible use as a biomarker for prostate cancer.
Prostate cancer exceeds lung cancer as the most commonly diagnosed cancer among men in the United States, with 220,900 new cases and 28,900 deaths in 2003. More than 70 percent of all prostate cancer cases are diagnosed in men over age 65.
The study was supported by a grant from Tessera Inc., Seattle, Wash. Co-authors include Rajiv Dhir, Ph.D., Barbara N. Vietmeier, Julie Arlotti, Ph.D., Marie Acquafondata, Ph.D., and Douglas Landsittel, Ph.D., of the University of Pittsburgh School of Medicine and Robert Materson, Ph.D., of Tessera Inc.