Discovery of protein that helps predict prostate cancer survival

An Oregon Health & Science University Cancer Institute researcher has identified a protein that is a strong indicator of survival for men with advanced prostate cancer. The C-reactive protein, also known as CRP, is a special type of protein produced by the liver that is elevated in the presence of inflammation.

"This could mean that a simple blood test that is already available could help in clinical decision making and patient counseling. Patients and doctors would know better what to expect from the prostate cancer they are facing," said Tomasz Beer, M.D., director of the Prostate Cancer Research Program at the OHSU Cancer Institute, associate professor of medicine (hematology/medical oncology), OHSU School of Medicine.

Beer's research will be published online in the journal Cancer on Monday, April 21.

Past research has shown that cancer causes an inflammatory response. This research also suggests that inflammation may play an important role in driving prostate cancer progression and resistance to therapy. Inflammatory cells are attracted to cancer sites and this local inflammation can lead to a release of inflammatory markers, like CRP.

"While inflammation may sometimes slow the progression of the cancer, an increasing body of evidence suggests that cancer can actually take advantage of the inflammatory response, and the reaction of the immune system may fuel cancer progression. To the extent that our hypothesis proves true, C-reactive protein may be reflecting the overall intensity of the inflammation," Beer said.

The finding that higher CRP is associated with shorter survival and a lower probability of response to chemotherapy is a result of a secondary analysis of inflammatory markers in patients enrolled in the ASCENT study, a large Phase 2 clinical trial that evaluated treatment with docetaxel and DN-101, a high dose formulation of calcitriol or docetaxel with placebo. This analysis included patients from both groups. The analyses were supported by Novacea Inc., the sponsor of the ASCENT study. This new finding was in collaboration with Novacea.

Because this is the first time CRP has been linked with both response and survival in study subjects with advanced prostate cancer receiving chemotherapy, it will be important to confirm this finding in an independent data set before this can become a routine blood test for men with advanced prostate cancer, Beer explained.

"If confirmed, besides providing useful information for the patient, this finding could also provide us with vital insight into the fundamental role of inflammation in the progression of advanced prostate cancer. A better understanding of this process could provide us with novel therapeutic interventions for control of this disease and its symptoms," Beer said.

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