California researchers say it may be possible to test the non-cancerous part of the prostate to detect prostate cancer (PCa), a novel approach that may aid in localization of cancer lesions within the prostate gland.

Dan Mercola, MD, PhD, and colleagues have identified gene expression changes in stroma that can detect a nearby tumor. The researchers compared gene expression profiles of 13 biopsies containing stroma near a prostate tumor and 15 biopsies from volunteers without PCa.

The investigators found about 3,800 significant expression changes and eliminated possible age-related genes and genes expressed at detectable levels in tumor cells. They constructed a stroma-specific classifier for nearby tumors on the basis of 114 candidate genes. They tested this classifier on 364 independent samples, including 243 tumor-bearing specimens and 121 non-tumor specimens. The classifier had 98% sensitivity and 88% specificity for predicting patients’ tumor status.

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“It is known that at least some prostate cancers cause a reaction in nearby stroma,” said Dr. Mercola, Professor of Pathology and Laboratory medicine at the University of California at Irvine. “However, we were surprised that a reaction may occur for most tumors, and that this response in non-tumor tissue may extend for many millimeters from the tumor.”

More than one million prostate biopsies are performed every year in the United States, Dr. Mercola noted. As many as one third of patients receive repeat biopsies within a year due to the presence of equivocal structures or due to continuing clinical suspicion. The current study demonstrates that the prostate cancer microenvironment exhibits reproducible changes that could be useful in categorizing the presence of a tumor when a prostate sample is derived from a nearby tumor.