Their small and preliminary study, was published in the Proceedings for the 2003 Annual Meeting of the American Association of Cancer Research, is important because the onset and progression of the disease appear to differ depending on race, but researchers do not know if this is a result of biological differences.
"Prostate cancer in African American men appears to behave aggressively, and that could be due to differences in the cancer's behavior and gene expression, or to delays in seeking treatment," says Curtis Pettaway, M. D., an associate professor in the Department of Urology and Cancer Biology.
The study was undertaken as part of a project that seeks to develop a novel test capable of predicting whether prostate cancer will metastasize, or spread, beyond the prostate organ.
Researchers are measuring the expression levels of two genes that paint a picture of whether or not cancer has moved beyond the confines of the prostate organ. One is the adhesion molecule E-cadherin which helps cells stick to each other. Low levels of E-cadherin are associated with cancer metastasis. Expression of two other molecules, matrix metalloproteinases (MMP 2 and 9), correlates strongly with aggressive prostate cancer.
Examining tissue samples from 21 African-American patients who had their cancerous prostates removed, Pettaway and his colleagues found that the ratio of MMP to E-cadherin accurately predicted which cancers had spread beyond the organ and which had not. A lot of MMP and little E-cadherin suggested the cancer had become invasive, where as less MMP and more E-cadherin predicted the cancer had stayed confined to the organ. The same trend was seen in a previous study of 40 Caucasian patients, Pettaway says. The investigators are planning a much larger study to actually compare the expression of these two genes among African American and Caucasian men with prostate cancer.
The test may someday be used, along with other risk analyses, to help patients and physicians decide on the best type of therapy based upon the test's prediction of whether the cancer has spread, he says.
Contact: Laura Sussman or Julie Penne, 713-792-0655