Stereotactic body radiation therapy (SBRT) for high-risk prostate cancer: Where are we now?

PURPOSE:Stereotactic body radiation therapy (SBRT) is increasingly being used for the management of localized prostate cancer. This trend combined with declining use of brachytherapy (BT) has pushed issues and questions regarding the use of SBRT to the forefront. A systematic literature review was conducted to review the current evidence of biochemical disease-free survival (bDFS) and toxicity of SBRT in high-risk (HR) prostate cancer. METHODS AND MATERIALS:A search was carried out on the PubMed and Embase databases. Studies were included if HR patients were treated using SBRT monotherapy or as a boost and bDFS was reported. Selected high-dose-rate (HDR) BT studies including HR patients from published reviews were selected to compare with SBRT results. Data from recent published phase 3 trials involving HR patients were also compared. RESULTS:Our search yielded 8862 articles. Of these, 20 studies with a median follow-up from 1.6 to 7 years were included in this review. The 5-year bDFS was 81% to 91% in monotherapy studies and 90% to 98% in boost studies. For reference, 19 studies that reported treating HR patients with HDR monotherapy or boost were selected. The 5-year bDFS in HDR monotherapy studies and boost studies was 85% to 93% and 72% to 93%, respectively. The incidence of late grade 3 genitourinary toxicity was 0% to 4.4% and 0% to 2.3% in SBRT monotherapy and SBRT boost studies, respectively. CONCLUSION:The evidence for SBRT in HR patients in this review is based on observational studies with relatively few patients and short follow-up (level III evidence). Based on these data and the principles surrounding treatment, SBRT boost should ideally be validated in clinical trials. SBRT monotherapy should be used cautiously in highly selected HR patients outside of a clinical trial. SUMMARY:Stereotactic body radiation therapy (SBRT) is increasingly being used for the management of clinically localized prostate cancer. This trend, combined with the decline in the use of brachytherapy, has pushed issues and questions regarding the use of SBRT to the forefront. A systematic literature review was conducted to establish the current evidence of biochemical and toxicity outcomes of SBRT in high-risk prostate cancer.