According to the American Cancer Society, over 186,000 Americans will be diagnosed with prostate cancer this year and nearly 29,000 will die from the disease. The team's findings could lead to a simple test that would help doctors determine which prostate cancers are slow-growing and which require immediate, aggressive treatment. Results of the study will appeared in the 12 February 2009 issue of the journal Nature.
"Our research has identified a potential biomarker that can detect prostate cancer and determine whether or not it is aggressive," said Debashis Ghosh, a Penn State associate professor of statistics and one of the paper's authors. Ghosh is a statistician who focuses on designing, interpreting, and analyzing data from genomic and cancer studies. "The experiments generated a flood of data, and without statistics, none of it would have made any sense," he said.
The researchers looked at 1,126 metabolites across 262 samples of tissue, blood, or urine associated with benign prostate tissue, early-stage prostate cancer, and advanced -- or metastatic -- prostate cancer. They identified about 10 metabolites that were present more often in diseased samples than in benign samples.
One metabolite in particular, sarcosine, appeared to be one of the strongest indicators of advanced prostate cancer. Levels of sarcosine, which is an amino acid, were elevated in 79 percent of the metastatic prostate cancer samples and in 42 percent of the early-stage cancer samples. Sarcosine was not found in the cancer-free samples. "The amount of sarcosine in urine was correlated with the aggressiveness of the prostate cancer," said Ghosh.
In the study, sarcosine was a better indicator of advancing disease than the traditional test for prostate-specific antigen, or PSA, that currently is used to monitor or screen for prostate cancer. Sarcosine was detected in the urine, and the researchers hope that a simple urine test may one day be developed to screen for prostate cancer. However, the team's results are preliminary at this point and will need years of further testing and development before this technology would be available for use with patients.
The research team is led by senior study author Arul Chinnaiyan, who is the director of the Michigan Center for Translational Pathology and the S.P. Hicks Endowed Professor of Pathology at the University of Michigan Medical School. The team includes researchers at the University of Michigan, Metabolon Inc., and Penn State. This research was funded by the National Cancer Institute Early Detection Research Network, the National Institutes of Health, an MTTC grant, the Burroughs Welcome Foundation, and the Doris Duke Charitable Foundation.