Abstract
Androgen deprivation therapy (ADT) remains the standard therapy for patients with oligometastatic prostate cancer (OMPC). Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT)-based stereotactic body radiotherapy (SBRT) is emerging as an alternative option to postpone starting ADT and its associated side effects including the development of drug resistance. The aim of this study was to determine progression free-survival (PFS) and treatment failure free-survival (TFFS) after PSMA-PET/CT-based SBRT in OMPC patients. The efficacy and safety of single fraction radiosurgery (SFRS) and ADT delay were investigated. Patients with ≤5 metastases from OMPC, with/without ADT treated with PSMA-PET/CT-based SBRT were retrospectively analyzed. PFS and TFFS were primary endpoints. Secondary endpoints were local control (LC), overall survival (OS) and ADT-free survival (ADTFS). Fifty patients with a total of 75 metastases detected by PSMA-PET/CT were analyzed. At the time of SBRT, 70% of patients were castration-sensitive. Overall, 80% of metastases were treated with SFRS (median dose 20 Gy, range: 16-25). After median follow-up of 34 months (range: 5-70) median PFS and TFFS were 12 months (range: 2-63) and 14 months (range: 2-70), respectively. Thirty-two (64%) patients had repeat oligometastatic disease. Twenty-four (48%) patients with progression underwent second SBRT course. Two-year LC after SFRS was 96%. Grade 1 and 2 toxicity occurred in 3 (6%) and 1 (2%) patients, respectively. ADTFS and OS rates at 2-years were 60.5% and 100%, respectively. In multivariate analysis, TFFS significantly improved in patients with time to first metastasis (TTM) >36 months (p = 0.01) and PSA before SBRT ≤1 ng/ml (p = 0.03). For patients with OMPC, SBRT might be used as an alternative to ADT. This way, the start/escalation of palliative ADT and its side effects can be deferred. Metastases treated with PSMA-PET/CT-based SFRS reached excellent LC with minimal toxicity. Low PSA levels and longer TTM predict elongated TFFS.
Highlights
For stage IV prostate cancer (PCA) palliative systemic therapy with androgen deprivation and/ or chemotherapy with docetaxel remains the standard of care [1]
Patients with 5 metastases from oligometastatic prostate cancer (OMPC), with/without Androgen deprivation therapy (ADT) treated with prostate-specific membrane antigen (PSMA)-positron emission tomography (PET)/CTbased stereotactic body radiotherapy (SBRT) were retrospectively analyzed
Fifty patients with a total of 75 metastases detected by PSMA-PET/CT were analyzed
Summary
For stage IV prostate cancer (PCA) palliative systemic therapy with androgen deprivation and/ or chemotherapy with docetaxel remains the standard of care [1]. Some patients with a limited number of metastases have a less aggressive disease course and might be treated with metastasis directed therapy (MDT) for all tumor sites as an alternative to systemic treatment [2]. These patients represent a condition known as oligometastatic disease, which is defined as an intermediate state between localized cancer and widespread metastases [3]. Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT)-based stereotactic body radiotherapy (SBRT) is emerging as an alternative option to postpone starting ADT and its associated side effects including the development of drug resistance. The efficacy and safety of single fraction radiosurgery (SFRS) and ADT delay were investigated
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