SUNDAY, May 18 (HealthDay News) — A therapeutic vaccine to treat prostate cancer appears safe and may be effective, according to the results of an early trial.

The vaccine could give hope to men with metastatic prostate cancer by activating their immune systems to fight the disease. The vaccine was developed to enable a patient’s immune system to produce anti-antigens and attack cancer cells, which can improve quality of life and extend survival.

“The primary objective of the study was to determine whether or not the vaccine was safe or whether it induced any serious adverse events,” said lead researcher Dr. David Lubaroff, director of urology research at the University of Iowa. “The vaccine was quite safe.”

In addition, the researchers wanted to see if the vaccine produced an immune response to prostate specific antigen (PSA).

“We found that 68 to 70 percent of the patients in the trial demonstrated immune responses to PSA,” Lubaroff said. “This was their last resort, and we were encouraged by the fact that we could detect any immune response in these patients.”