Protein may be marker for aggressive prostate cancer

British scientists have discovered that the presence of a specific protein can distinguish between indolent and aggressive prostate cancer.

Their study, which was published online in Oncogene (Nov. 18, 2013), found much higher levels of the protein, NAALADL2, in prostate cancer tissue compared with healthy tissue. The difference was especially marked in aggressive prostate cancer tumors and cancer cells that had already metastasized.

The authors, who conducted the research as part of the charity Cancer Research UK, confirmed in two independent patient groups that the protein could be used to diagnose prostate cancer. More important, it found that high levels of the protein could potentially pinpoint those patients with aggressive disease who would need surgery, chemotherapy, and radiotherapy. Patients with lower levels of the protein were more likely to need monitoring rather than treatment.

Researchers say the NAALADL2 protein causes prostate cancer cells to behave more aggressively, making them more likely to move and invade healthy tissue surrounding the tumor.

“This is early research, but if clinical trials confirm our results then it could help clinicians to tell which patients have a more aggressive tumor and need proportionally aggressive treatment, while sparing patients with low-grade tumors an unnecessary radiotherapy or surgery,” said lead author Hayley Whitaker, PhD, of the University of Cambridge, Cambridge, United Kingdom.

“This is an important step along the path to developing a much-sought after test that could distinguish between different types of prostate cancer,” Dr. Whitaker added.

“As a prostate cancer clinician, I have been waiting for years for a test that can define the aggressive disease,” said Malcolm Mason, MD, of Cardiff University, Cardiff, United Kingdom, who serves as Cancer Research UK’s prostate cancer expert. “I hope that this research brings forward the day when I can say to patients: ‘We know that your cancer doesn’t need treatment’-a crucial development that could spare thousands of patients from enduring arduous treatment with unpleasant side effects.

“This extremely interesting study provides an important development for prostate cancer screening, and potentially even reveals a new target for the development of new prostate cancer drugs in the future.”

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