Stereotactic Body Radiotherapy for Oligometastatic Prostate Cancer Recurrence

Abstract

Purpose: The purpose of this study was to evaluate the treatment efficacy of stereotactic body radiotherapy (SBRT) in oligometastatic prostate cancer recurrence and to assess whether there is any relationship between biologically effective dose (BED) and local control (LC). Materials and Methods: Eligible studies were identified on Medline, Embase, and the Cochrane Library, and the proceedings of annual meetings through May 2019 were also identified. A meta-regression analysis was performed to assess whether there is a relationship between BED and LC. In the univariate analysis, studies were separated by the study design, the number of metastatic sites, the site of metastases, radiotherapy machine, and prostate-specific antigen level at the time of SBRT. A P-value <0.05 was considered significant. Results: Twenty-three observational studies with a total of 1441 lesions treated were included in the meta-analysis. The proportional rate of LC, progression-free survival, and androgen deprivation–free survival was 0.976 (95% confidence interval [CI]: 0.96-0.98), 0.413 (95% CI: 0.378-0.477), and 20.1 months (95% CI: 14.5-25.6), respectively. In the meta-regression, a linear relationship between BED and LC was detected (P=0.017). Stratifying the BED into 3 levels (BED<100 Gy3, BED 100 to 130 Gy3, and BED>130 Gy3), a significant difference was observed between BED<100 Gy3 (LC=88%) versus BED>100 Gy3 (LC=96%). The rate of any acute and late grade ≥2 toxicity was 1.3% and 1.2%, respectively. Conclusions: The LC rate with SBRT was excellent with minimal severe acute/late toxicity. Our data suggest a dose relationship between BED and LC, with BED >100 Gy3 resulting in better rates of LC.

Oligorecurrent Prostate Cancer and Stereotactic Body Radiotherapy: Where Are We Now? A Systematic Review and Meta-analysis of Prospective Studies

“…Certainly, data supporting MDT, in particular SBRT, could not be ignored even if provided mostly by retrospective studies. A recent systematic review by Viani et al [25] , including 23 observational studies with a total of 1441 lesions treated with SBRT, showed excellent rates of local control (0.976; 95% CI, 0.96–0.98) and ADT-free survival of 20.1 mo, with low rates of acute and late moderate-to-severe toxicity events (1.3% and 1.2%, respectively).…”

SBRT in Lymph-Nodal Oligometastases from Prostate Cancer: Different Outcomes between Pelvic and Para-Aortic Disease

“…SBRT is widely accepted as an effective treatment for oligometastases and PC patients may benefit from MDT in both hormone-sensitive and castration-resistant settings. Patients affected by nodal-exclusive OMD are typically characterized by a more indolent disease than those affected by polymetastatic or visceral metastases: in this setting, local treatments, such as SBRT, are able to delay the start of systemic therapy, prolong its duration, or postpone the switch to a subsequent treatment line [19,[22][23][24]. No statistical differences were recorded between the two groups in CRFS, PMFS, and LPFS.…”

“…Patients with PC nodal metastases generally have a better prognosis than those with bone or visceral metastases [ 18 ]. The use of SBRT is well-established in clinical practice for oligometastatic pelvic lymph nodes due to its excellent local control [ 19 ]. However, only a few studies have evaluated the use of MDT on para-aortic lymph nodes.…”

Oligometastatic Prostate Cancer—The Middle Child Syndrome

“…This important observation was further substantiated by a comprehensive metaanalysis spanning both trials. Consequently, this collective body of evidence has firmly established a gold standard of care in the local control of the primary tumour with radiotherapy for patients characterized by synchronous low-volume metastases [34].…”