(UroToday.com) Dr. Piet Ost discussed results of a pooled analysis of prospective trials assessing metastasis-directed therapy for oligorecurrent prostate cancer at the 2021 EAU’s annual meeting metastatic prostate cancer session. To date, prospective data for metastasis-directed therapy for oligorecurrent prostate cancer have been limited to single arm or small phase 2 randomized studies. The objective of this study was to conduct an individual patient data meta-analysis to characterize the safety and clinical benefit of metastasis-directed therapy in oligorecurrent prostate cancer.
Dr. Ost and colleagues searched for prospective trials investigating the safety and clinical benefit of metastasis-directed therapy in oligorecurrent prostate cancer in trial registries and conference proceedings until January 2020. Inclusion criteria were single- or multi-arm prospective trials including only patients with recurrent prostate cancer and a limited number of recurrences (ie, ≤5 sites of extracranial disease) undergoing metastasis-directed therapy (surgery or radiotherapy). ADT-free survival was analyzed as the primary outcome, and biochemical relapse free survival as secondary outcome. If hazard ratios were not constant across the different trials, standardized survival curves were calculated, analyzing the trials separately and pooling the adjusted log HR, weighted by sample size. The following covariates were examined with the interaction test: PSA doubling time and localization of disease (nodal vs. extra-nodal).
There were 4 trials that were identified with published results (STOMP, ORIOLE, POPSTAR and PSMA MgRT): two single arm and two randomized trials, representing in total 174 patients (metastasis-directed therapy: 72%, active surveillance: 28%). Patient characteristics differed with respect to imaging at inclusion, PSA doubling time and localization of disease (nodal vs. extra-nodal). For ADT-free survival, non-proportional hazards were detected, but not for biochemical relapse-free survival. ADT-free survival is improved with metastasis-directed therapy over active surveillance (HR: 0.56, 95%CI 0.34 – 0.94, p=0.03) across all covariates:
Additionally, metastasis-direct therapy also improved biochemical-free survival (HR: 0.44, 95%CI 0.29 – 0.67, p<0.01): 
Grade 2 and 3 toxicity were observed in 3% and 2%, respectively, of cases treated with metastasis-directed therapy.
Dr. Ost concluded his presentation emphasizing that metastasis-directed therapy improves both biochemical-free and ADT-free survival as compared to active surveillance in oligorecurrent prostate cancer with low rates of grade 3 or higher toxicity.
Presented by: Piet Ost, MD, Ph.D., Radiation Oncologist, Assistant professor, Faculty of Medicine and Health Sciences, Ghent University Hospital, Member of the Steering Committee of ION (immuno-oncology network) Ghent Vice-chairman of the Young Academic Urologist Prostate Cancer Working group of the EAU, Ghent, Belgium
Co-Authors: Alejandro B.2, Siva S.3, Reynders D.4, Phillips R.M.5, Glicksman R.2, Foroudi F.3, Fonteyne V.1, Deek M.P.6, Chung P.2, Murphy D.7, Tran P.T.6
1Ghent University, Dept. of Human Structure and Repair, Ghent, Belgium, 2University of Toronto, Radiation Medicine Program, Princess Margaret Cancer Centre, Dept. of Radiation Oncology, Toronto, Canada, 3Peter MacCallum Cancer Center, Dept. of Radiation Oncology, Melbourne, Australia, 4Ghent University, Dept. of Applied Mathematics, Computer Science and Statistics, Ghent, Belgium, 5Mayo Clinic, Dept. of Radiation Oncology, Rochester, United States of America, 6John Hopkins, Dept. of Radiation Oncology, Baltimore, United States of America, 7Peter MacCallum Cancer Center, Dept. of Urology, Melbourne, Australia
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2021 European Association of Urology, EAU 2021- Virtual Meeting, July 8-12, 2021.