Our results suggest a significant inhibition of progressive disease given the effect on PSA doubling time with GTN treatment compared to their doubling time prior to initiating the trial. Within 12 months of the trial, 17 of 24 patients had doubling times in the slow category or even stable/declining PSA levels. The mean doubling time of the entire cohort increased to 31.8 months from 13.2 months prior to starting treatment. When compared to a matched control group of patients with PSA recurrence that did not receive any treatment, a similar significant difference in PSA doubling time was observed. There were no adverse effects reported in this trial.