Phase II trial of SBRT and Hormone therapy for Oligometastases in Prostate Cancer (SBRT-SG 05)

Purpose or Objective SBRT-SG 05 (ClinicalTrials.gov Identifier: NCT02192788) is a collaborative (SBRT-SG, GICOR and SEOR) prospective multicenter phase II trial testing SBRT and hormone therapy in oligometastatic prostate cancer patients. Material and Methods Prostate cancer patients (hormone-sensitive or castration-resistant) in an oligorrecurrent stage defined as less than 5 bone or lymph node metastases (including spinal bones) by Choline PET-CT or/and WB-DWI-MRI after primary treatment for their disease, were assigned to receive SBRT (Vertebral metastases: 1x16-18Gy or 3x8- 9Gy. Lymph node metastases: 3x10-11 Gy or 6x7,5Gy. Non-spinal bone metastases: 1x16Gy or 3x10Gy). Inclusion criteria included: Time from primary treatment to biochemical recurrence of more than 1 year and PSA doubling time> 2 months. A minimum of 24 months of LhRh analogues from the time of the enrollment was required. Local control rates, biochemical control rates, progression free survival, chemotherapy free survival and SBRT impact on patient's quality of life were assessed. Toxicity was prospectively evaluated according to CTCAE criteria. Concomitant treatment with chemotherapy, abiraterone or enzalutamide was not allowed. Results From 07/2014 to 06/2017, 67 patients from 11 Spanish centers were recruited with a total of 100 oligometastases treated, 54 in lymph nodes, 42 in non-spinal bones and 4 in spinal bones. Twelve patients had castration-resistance disease. With a median follow-up after SBRT of 9 months, (range 1-30 months) local and biochemical control was 100%. Ten patients (15%) presented distant disease progression, 4 of them were castration-resistant (CRPC). Specifically, in patients with CRPC, after a median follow- up of 9.8 months, 8 of the 12 CRPC patients (66%) are free from disease progression at last follow-up, without the need to start second generation hormonal treatment. Tolerance and toxicity profiles were excellent, none of the patients developed toxicity ≥G3 or symptoms related to local progression of the disease. Conclusion Preliminary results of this trial demonstrate that combination of SBRT and ADT is safe treatment with encouraging local and biochemical control.