FRIDAY, June 1, 2007 (HealthDay News) -- A protein that is used as a marker of heart disease may also predict survival odds and response to chemotherapy for men with advanced prostate cancer.
There is already a simple blood test available for the protein, called C-reactive protein (CRP), which is produced by the liver and is elevated in the presence of inflammation.
"If a second study is confirmatory, then we have a readily available blood test that could now be used to inform physicians and patients what they can expect from the cancer, which is important in planning treatment," said study senior author Dr. Tomasz Beer, director of the prostate cancer research program at the Oregon Health & Science University Cancer Institute.
The findings are expected to be presented June 1 at the American Society of Clinical Oncology meeting in Chicago.
Over the last several years, investigators have begun looking at the role of CRP in a range of cancers. "There's a growing body of information that suggests that inflammation may be an important driver of cancer progression," Beer explained.
Smaller studies have suggested that higher CRP levels were associated with a worse prognosis specifically in prostate cancer patients. This study appears to be the first to look at a large number of prostate cancer patients receiving modern chemotherapy.
"This is the first such solid report from a large patient set," Beer said.
Prostate-specific antigen (PSA) is widely used as a marker for prostate cancer, but it has limitations. "There are a number of patients with very aggressive prostate cancer who don't make a lot of PSA. PSA sometimes isn't helpful in assessing people who have really aggressive disease," said Dr. Naomi Haas, a medical oncologist of genitourinary malignancies at Fox Chase Cancer Center in Philadelphia. "Sometimes there's a rise in PSA but we see a clinical improvement overall. So, doctors are busy looking at other options."
The current paper is actually a secondary analysis of a study originally published in the Feb. 20 issue of the Journal of Clinical Oncology.
The trial involved 160 men with advanced prostate cancer, who were either taking docetaxel (Taxotere, a chemotherapy drug) plus a newer drug, Asentar, or docetaxel alone.
The analyses were supported by Novacea Inc., which makes both Taxotere and Asentar. Both OHSU and Beer have financial interests in the company.
Men taking both drugs had about a 49 percent improvement in survival and a 34 percent reduction in serious side effects, as compared with those taking Taxotere alone.
CRP was the only biomarker surveyed (others included PSA) that predicted shorter survival.
"In our analysis, CRP was much more predictive of survival than PSA was so, from that perspective, it's a potentially better test," Beer said.
PSA has been used both for early detection of prostate cancer and for monitoring the progression of the cancer. CRP has only been looked at for monitoring progression. "We're talking about very advanced patients with extensive cancer," Beer said. "There's no information that CRP would be useful when the cancer is tiny and probably there's not a lot of inflammation."
However, CRP may have potential both in prognosis and also in cancer biology.
"This gives us a lot of ideas as to how we might be able to better treat cancer in targeting inflammation as well as cancer," Beer said.
But the findings need to be replicated before they become a part of clinical practice.
"Any time we find a new prognostic marker, it really needs to be looked at in a second group of patients to make sure it holds up reliably," Beer said. "There needs to be a second study, and we're working towards that as we speak."
There's more on prostate cancer at the U.S. National Cancer Institute.