Peek Into Future of Prostate Cancer
Prostate Cancer Vaccine, Better Tests May Be Just Over the Horizon
Don't Watch and Wait -- Vaccinate continued...
"The equivalent in a man is very clear. In the U.S., for instance, some 90,000 to 100,000 men every year are diagnosed with high-grade PIN," Kast says. "That is the exact equivalent of the disease stage in mice. So there is a group of men that could benefit very much from this approach."
A big worry is that the vaccine's target is a protein found on normal cells in the esophagus, bladder, and stomach. But at least in mice, the vaccine did not harm these organs.
"I think the explanation is that the expression levels of this protein, PSCA, is so low in normal tissue that the immune system makes a differentiation between prostate cancer cells that make this antigen and normal cells," Kast says.
Kast says his team could produce a human vaccine in about two years. Any actual vaccine treatment would need years of testing before it became available, notes Durado Brooks, MD, MPH, director of prostate and colorectal cancers for the American Cancer Society, Atlanta.
"I would hesitate to get too excited about this vaccine study, since we are at this point we are talking about mice -- and the jump from mice to men is usually many years in the making," Brooks tells WebMD. "It certainly does open the door to some potentially exciting avenues, but we are not right around the corner from being able to duplicate these results in human populations."
Better Prostate Cancer Test?
A major problem with the PSA prostate cancer screening test is that it looks for only one prostate-specific protein, notes Arul M. Chinnaiyan, MD, PhD, professor of pathology and urology at the University of Michigan.
Chinnaiyan's team is therefore looking at what they call a "multiplex" test that will look for a number of prostate cancer markers. In their current study, they have looked at four such markers in the urine of 234 men whose high PSA levels caused them to have prostate biopsies.
The new test wasn't perfect. But it identified 80% of the men who turned out to have prostate cancer. And it was able to rule out prostate cancer in 61% of the men whose biopsies were negative.