Corey Foster, Presenter: Nothing to Disclose

William Jackson MD, Abstract Co-Author: Nothing to Disclose

Benjamin Foster BS, Abstract Co-Author: Nothing to Disclose

Skyler Johnson MD, Abstract Co-Author: Nothing to Disclose

Felix Yi-Chung Feng MD, Abstract Co-Author: Nothing to Disclose

Daniel Allan Hamstra MD, PhD, Abstract Co-Author: Research Grant, Novartis AG Speaker, Varian Medical Systems, Inc

Purpose/Objective(s): The appropriate time to initiate salvage androgen deprivation therapy (SADT) following the treatment and biochemical recurrence of localized prostate cancer remains controversial. We chose to investigate if early initiation of SADT is associated with improved clinical outcomes following biochemical failure (BF) post-salvage radiation therapy (SRT).Materials/Methods: The medical records of 575 patients treated with SRT at a single institution between 1986 and 2010 were retrospectively reviewed. Of the 250 patients experiencing BF post-SRT, 172 patients (69%) had a calculable prostate-specific antigen doubling time (PSADT) prior to initiation of SADT. These patients comprise the cohort used for analysis and were divided into four groups as follows: those with PSADTs > 3 months without distant metastasis (DM) at SADT initiation (group 1, n=62), those with PSADTs < 3 months without DM at SADT initiation (group 2, n=28), those with DM at SADT initiation (group 3, n=32), and those not receiving SADT during follow-up (group 4, n=50). Group 1 was considered to have received early SADT while groups 2 and 3 were considered to have received late SADT. Endpoints included prostate cancer-specific mortality (PCSM) and overall mortality (OM). Kaplan-Meier methods were used to estimate survival, and Cox proportional hazards models were used for multivariate analysis.Results: Median follow-up post-SRT was 7.9 years. PCSM significantly differed among the four groups (p=0.001) with 5-year rates of PCSM being 3%, 24%, 13%, and 0% for groups 1-4, respectively. PCSM and OM did not significantly differ between groups 1 and 4 or groups 2 and 3. Of note, patients in group 4 had a median follow-up post-BF of 3.6 years (range: 0.4-15.3) and had very long PSADTs (median = 27.0 months, interquartile range [IQR]: 13.6-47.7) that were significantly longer than those of group 1 (median = 6.0 months, IQR: 4.5-9.5) (p<0.001). Patients receiving late SADT were at significantly increased risk for PCSM (hazard ratio [HR]:2.8, 95% confidence interval [CI]: 1.4-5.5, p=0.005) and OM (HR:1.9, 95%CI: 1.0-3.5, p=0.04) compared to those receiving early SADT. Multivariate analysis including groups 1-3 while controlling for comorbidity, pathologic variables, presence of DM at SADT initiation, and PSA at SADT initiation found a pre-SADT PSADT < 3 months to be the only significant predictor of PCSM (HR: 4.0, 95%CI: 1.6-10.1, p=0.003) and OM (HR:2.9, 95%CI: 1.3-6.5, p=0.009).Conclusions: For patients experiencing BF post-SRT, early initiation of SADT is associated with decreased PCSM and OM; however, observation may be a reasonable alternative for patients with very long PSADTs. A PSADT < 3 months prior to SADT initiation significantly predicts an increased risk of PCSM and OM in this patient demographic.

Foster, C, Jackson, W, Foster, B, Johnson, S, Feng, F, Hamstra, D, Early Initiation of Salvage Androgen Deprivation Therapy Is Associated with Decreased Mortality Following Biochemical Failure Post-Salvage Radiation Therapy.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14041547.html