BALTIMORE, March 21 (UPI) -- U.S. researchers said quick application of a new prostate-cancer vaccine may be the best way of treating the disease.
Researchers at Johns Hopkins University studied mice bred to develop the cancer. They found that the animal's immune system recognizes the cancer but cannot mount an effective counterattack -- probably because its immune cells become tolerant of the slow-growing cancer.
"The window of opportunity is narrow for vaccination, designed to reinvigorate the immune system's attack on cancer cells," said lead researcher Dr. Charles Drake. "It occurs right after hormonal therapy begins to wipe out the tumor and immune cells outnumber cancerous ones."
Drake and colleagues found if they used a newly developed vaccine to activate the immune system right after giving the mice hormone therapy to shrink their tumors, the cancer-fighting T-cells swing into action.
T-cells multiplied three times as much in the prostate-cancer mice if they were vaccinated immediately after hormone therapy, compared with those not receiving the therapy.
Prostate cancer is the leading cause of cancer deaths in American men, and the average time of relapse after hormone therapy treatments is approximately two years.