The use of stereotactic body radiation therapy on oligometastatic recurrent prostate cancer: a systematic review

Abstract

To evaluate the effectiveness and safety of stereotactic body radiation therapy (SBRT) in the management of oligometastatic recurrent prostate cancer patients (ORPCP) by means of a systematic review. The focus was on clinical implications. Methods and Materials: Six databases were searched (Cochrane CENTRAL, Embase, LILACS, PubMed, Scopus, Web of Science). Hand-searching and gray literature search were also performed to find additional references. The main outcomes were progression free survival (PFS) and toxicity rates. ADT-free survival (ADT-FS), local control, pattern of clinical recurrence following SBRT, cancer-specific survival and overall survival were also assessed. Risk of bias of individual studies were judged with aid of the Joanna Briggs Institute Critical Appraisal Checklist for Case Series. Quality of evidence was assessed with Grades of Recommendation, Assessment, Development, and Evaluation (GRADE). Results: Fourteen studies were included, involving 661 patients and 899 metastatic lesions. No randomized controlled trials were found. The articles are from 2011 to 2017. Nine of them were published in 2016 or later. Were treated 561 nodal, 336 bone and 2 liver lesions with SBRT. Adjuvant ADT at time of SBRT was used on 38.7% of the patients. The medians PFS and ADT-FS were around 1 and 3 years after intervention. Local control rates varied from 82 to 100% among researches with low risk of bias. Acute and late grade 2 toxicity were observed in 2.4% and 1.1% of the patients, respectively. One case of acute and two cases of late grade 3 toxicity were registered. Conclusion: SBRT is a safe approach to prostate cancer metastases. It has the potential to provide long-term disease control and to defer ADT. The local control is excellent, especially when higher radiation doses are employed. Despite promising results, further investigation with randomized controlled trials are required.