Reduction of serum prostate-specific antigen levels following varicella-zoster infection and valaciclovir treatment in prostate cancer.

We present two prostate cancer patients, including one with a castration-resistant cancer whose rising serum prostate-specific antigen (PSA) levels showed a remarkable drop after a reactivated varicella-zoster virus infection treated with valaciclovir. In one patient, we found a temporary decrease in serum PSA lasting for at least 4 mo. In the patient with castration-resistant prostate cancer, serum PSA decreased to <0.01 microg/l and has remained undetectable since.