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Can we avoid high levels of dose escalation for high-risk prostate cancer in the setting of androgen deprivation?

Authors Shakespeare T, Wilcox S, Aherne N

Received 27 January 2016

Accepted for publication 1 April 2016

Published 11 May 2016 Volume 2016:9 Pages 2819—2824

DOI https://doi.org/10.2147/OTT.S105174

Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Triparna Sen

Peer reviewer comments 4

Editor who approved publication: Professor Min Li


Thomas P Shakespeare,1,2 Shea W Wilcox,1 Noel J Aherne1,2

1Department of Radiation Oncology, North Coast Cancer Institute, 2Rural Clinical School, Faculty of Medicine, University of New South Wales, Coffs Harbour, NSW, Australia

Aim: Both dose-escalated external beam radiotherapy (DE-EBRT) and androgen deprivation therapy (ADT) improve outcomes in patients with high-risk prostate cancer. However, there is little evidence specifically evaluating DE-EBRT for patients with high-risk prostate cancer receiving ADT, particularly for EBRT doses >74 Gy. We aimed to determine whether DE-EBRT >74 Gy improves outcomes for patients with high-risk prostate cancer receiving long-term ADT.
Patients and methods: Patients with high-risk prostate cancer were treated on an institutional protocol prescribing 3–6 months neoadjuvant ADT and DE-EBRT, followed by 2 years of adjuvant ADT. Between 2006 and 2012, EBRT doses were escalated from 74 Gy to 76 Gy and then to 78 Gy. We interrogated our electronic medical record to identify these patients and analyzed our results by comparing dose levels.
Results: In all, 479 patients were treated with a 68-month median follow-up. The 5-year biochemical disease-free survivals for the 74 Gy, 76 Gy, and 78 Gy groups were 87.8%, 86.9%, and 91.6%, respectively. The metastasis-free survivals were 95.5%, 94.5%, and 93.9%, respectively, and the prostate cancer-specific survivals were 100%, 94.4%, and 98.1%, respectively. Dose escalation had no impact on any outcome in either univariate or multivariate analysis.
Conclusion: There was no benefit of DE-EBRT >74 Gy in our cohort of high-risk prostate patients treated with long-term ADT. As dose escalation has higher risks of radiotherapy-induced toxicity, it may be feasible to omit dose escalation beyond 74 Gy in this group of patients. Randomized studies evaluating dose escalation for high-risk patients receiving ADT should be considered.

Keywords: radiotherapy, IMRT, dose, dose escalation, dose de-escalation, androgen deprivation therapy, prostate cancer

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