Stereotactic Body Radiotherapy for Oligometastatic Prostate Cancer

Publication date: Available online 29 January 2016
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Jonathan L. Muldermans, Lindsay B. Romak, Eugene D. Kwon, Sean S. Park, Kenneth R. Olivier
Purpose/Objective(s)To review outcomes of patients with oligometastatic prostate cancer (PCa) treated with stereotactic body radiotherapy (SBRT) and to identify variables associated with local failure.Methods and MaterialsWe retrospectively reviewed records of patients treated with SBRT for oligometastatic PCa. Metastasis control (i.e. control of the treated lesion, MC), biochemical progression-free survival (BPFS), distant progression-free survival (DPFS), and overall survival (OS) were estimated with the Kaplan-Meier method.ResultsSixty-six men with 81 metastatic PCa lesions, 50 of which were castrate-resistant, were included in the analysis. Lesions were in bone (n=74), lymph nodes (n=6), or liver (n=1). SBRT was delivered in 1 fraction to 71 lesions (88%), at a median dose of 16 Gy (range, 16-24 Gy). The remaining lesions received 30 Gy in 3 fractions (n=6) or 50 Gy in 5 fractions (n=4). Median follow-up was 16 months (range, 3-49 months). Estimated MC at 2 years was 82%. BPFS, DPFS, and OS were 54%, 45%, and 83%, respectively. On multivariate analysis, only the dose of SBRT was significantly associated with MC; lesions treated with 16 Gy had 58% MC and those treated with ≥18 Gy had 95% MC at 2 years (P≤.001). At 2 years, MC for lesions treated with 18 Gy (n=21) was 88%. No patient treated with ≥18 Gy in a single fraction or with any multi-fraction regimen had local failure. Six patients (9%) had grade 1 pain flare, and 2 (3%) had grade 2 pain flare. No grade 2 or greater late toxicities were reported.ConclusionsSBRT for patients with oligometastatic prostate cancer provided optimal metastasis control and acceptable toxicity with doses ≥18 Gy. BPFS was 54% at 16 months with the inclusion of SBRT in the treatment regimen. SBRT should be considered in patients with castration-refractory, oligometastatic prostate cancer who have limited options for systemic therapy.

Teaser

Use of stereotactic body radiotherapy (SBRT) has been reported in the treatment of oligometastatic prostate cancer; however, the optimal dose fractionation has not been elucidated. This analysis indicates that single-fraction SBRT using 16 Gy is associated with poorer local control relative to single-fraction SBRT using ≥18 Gy or higher-dose, multi-fraction SBRT regimens. Toxicity was acceptable in this series.


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