"If this vaccine proves to induce a strong anti-PSA immune response, and if there is a correlation between this PSA response and an effect on the disease, then we could use this vaccine as another therapy," Lubaroff said.
One expert is skeptical that this vaccine will ever prove to be a viable treatment.
"I think about all you can prove from this kind of study is safety," said Dr. Bruce Roth, a professor of medicine and urology at Vanderbilt University. "But that's a world of difference from saying that there is evidence of efficacy."
Roth doesn't think changes in PSA in this kind of trial are enough to prove the vaccine works.
"I would not take away from this that this is the breakthrough we have been waiting for, for 35 years," Roth said. "It's an OK theory, but we have been disappointed a lot in the past couple of decades with immune therapies that look great but never produce the results we had hoped for."
Another study expected to be presented Sunday showed that a PSA reading taken between the ages of 45 and 50 actually helps predict prostate cancer up to 30 years later. These findings suggest that prostate cancer may start to develop very early and that PSA levels affect the development of prostate cancer.
A third study found that black men who have a family history of prostate cancer could benefit from a PSA reading, which could determine their probability of developing the disease.
Black men who have known risks for prostate cancer and higher levels of PSA are more likely to develop the disease, compared with people in the general population.
However, black men with a family history of prostate cancer are unlikely to develop the disease if their baseline PSA was below what is normal for their age. The effect of family history and PSA level actually overrode other prostate cancer risk factors, the researchers said
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