Does brachytherapy boost improve survival outcomes in Gleason Grade Group 5 patients treated with external beam radiotherapy and androgen deprivation therapy? A systematic review and meta-analysis

Terence Tang; Stephanie Gulstene; Eric McArthur; Andrew Warner; Gabriel Boldt; Vikram Velker; David D'Souza; Glenn Bauman; Lucas C Mendez

doi:10.1016/j.ctro.2022.10.010

Does brachytherapy boost improve survival outcomes in Gleason Grade Group 5 patients treated with external beam radiotherapy and androgen deprivation therapy? A systematic review and meta-analysis

Clin Transl Radiat Oncol. 2022 Oct 29:38:21-27. doi: 10.1016/j.ctro.2022.10.010. eCollection 2023 Jan.

Authors

Terence Tang¹, Stephanie Gulstene¹, Eric McArthur¹, Andrew Warner¹, Gabriel Boldt¹, Vikram Velker¹, David D'Souza¹, Glenn Bauman¹, Lucas C Mendez¹

Affiliation

¹ Department of Radiation Oncology, London Regional Cancer Program, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada.

Abstract

Background: Localized Gleason Grade Group 5 (GG5) prostate cancer has a poor prognosis and is associated with a higher risk of treatment failure, metastases, and death. Treatment intensification with the addition of a brachytherapy (BT) boost to external beam radiation (EBRT) maximizes local control, which may translate into improved survival outcomes.

Methods: A systematic review and meta-analysis was performed to compare survival outcomes for Gleason GG5 patients treated with androgen deprivation therapy (ADT) and either EBRT or EBRT + BT. The MEDLINE (PubMed), EMBASE and Cochrane databases were searched to identify relevant studies. Survival probabilities for distant metastasis-free survival (DMFS), prostate cancer-specific survival (PCSS), and overall survival (OS) were extracted and pooled to create a summary survival curve for each treatment modality, which were then compared at fixed points in time. An additional analysis was performed among studies directly comparing EBRT and EBRT + BT using a random-effects model.

Results: Eight retrospective studies were selected for inclusion, representing a total of 1393 EBRT patients and 877 EBRT + BT patients. EBRT + BT was associated with higher DMFS starting at 6 years (86.8 % vs 78.8 %; p = 0.018) and extending out to 10 years (81.8 % vs 66.1 %; p < 0.001), with an overall hazard ratio of 0.53 (p = 0.02). There was no difference in PCSS or OS between treatment modalities. Differences in toxicity were not assessed. There was a wide range of heterogeneity between studies.

Conclusion: The addition of BT boost is associated with improved long-term DMFS in Gleason GG5 prostate cancer, but its impact on PCSS and OS remains unclear. These results may be confounded by the heterogeneity across study populations with concern for a risk of bias. Therefore, prospective studies are necessary to further elucidate the survival advantage associated with BT boost, which must ultimately be weighed against the toxicity-related implications of this treatment strategy.

Keywords: Brachytherapy boost; External beam radiotherapy; Gleason Grade Group 5; Prostate cancer; Survival outcome.