A Review of Stereotactic Body Radiation Therapy in the Management of Oligometastatic Prostate Cancer.

Abstract

Management strategies such as surgery and systemic therapy (androgen-deprivation therapy and chemotherapy) are considered a standard of care for patients with oligometastatic prostate cancer and have shown some positive results in many patients. However, they are often accompanied by side-effects that can negatively affect patients. The aim of this study is to review the potential of stereotactic body radiation therapy (SBRT) in the management of oligometastatic prostate cancer and to compare treatment outcomes with SBRT to those under standard of care management regarding progression-free survival (PFS), androgen-deprivation therapy (ADT)-free survival and local control rate (LCR) as well as a comparison of toxicity profiles. MEDLINE (PubMed), EMBASE, and Clinicaltrials.gov databases were searched to identify prospective randomised controlled trials as well as retrospective studies investigating SBRT and standard of care management for oligometastatic prostate cancer. Data on treatment outcomes and toxicity profiles were extracted. A total of 18 studies were included: 14 reported on the use of SBRT and four reported on the use of standard of care management. For SBRT, median PFS was 7.36-24 months. Median ADT-free survival was 12.3-39.7 months. The LCR varied, with some reports of 100% at 6 months and others of 92% at 5 years. No significant grade 3 toxicity was reported, with only five grade 3 events reported in two studies. For standard of care management, most of the studies reported 3-year PFS of 46.9-58.6%, with one study reporting a median PFS of 38.6 months. No standard of care study reported on LCR and ADT-free survival. Although different toxicity grading systems were used depending on the treatment modality, there were some reports of grade 3 events using standard of care management. SBRT appears to be a safe and effective modality for treating oligometastatic prostate cancer, having the potential to defer palliative ADT. Although LCR is excellent compared to conventional therapies, the PFS rate is reportedly inferior to standard of care therapies. No significant grade 3 toxicity was observed with SBRT.