Stereotactic body radiotherapy versus conventional/moderate fractionated radiation therapy with androgen deprivation therapy for unfavorable risk prostate cancer

Sagar A Patel,Ashesh B Jani,Jeffrey M Switchenko,Ben Fischer-Valuck,Trevor J Royce,Chao Zhang,Brent S Rose,Ronald C Chen

doi:10.1186/s13014-020-01658-5

Abstract

BackgroundUltrahypofractionation using stereotactic body radiotherapy (SBRT) is an increasingly utilized technique for men with prostate cancer (PC). The comparative efficacy of SBRT plus androgen deprivation therapy (ADT) compared to fractionated radiotherapy (EBRT) plus ADT in higher-risk prostate cancer is unknown.MethodsMen > 40 years old with localized PC treated with external beam radiation and concomitant ADT for curative intent between 2004 and 2016 were analyzed from the National Cancer Database. Patients who lacked ADT or risk stratification data were excluded. 558 men treated with SBRT versus 40,797 men treated with conventional or moderately hypofractionated EBRT were included. Patients were stratified by unfavorable intermediate (UIR) and high (HR) risk using NCCN criteria. Kaplan Meier and Cox proportional hazards were used to compare overall survival (OS) between RT modality, adjusting for age, race, and comorbidity index.ResultsWith a median follow up of 74 months, there was no difference in estimated 6-year OS between men treated with SBRT versus EBRT regardless of risk group. On multivariable analysis, there was no difference in risk of death for men treated with SBRT compared to EBRT (UIR: adjusted HR 1.09, 95% CI 0.68–1.74, p = .72; HR: adjusted HR 0.93, 95% CI 0.76–1.14, p = .51). On sensitivity analyses, when confining the cohort to men treated with NCCN-preferred dose fractionations, with no comorbidities, or < 65 years old, there remained no survival difference between treatment groups for both UIR and HR.ConclusionWithin study limitations, we found no difference in survival between SBRT+ADT and standard of care EBRT+ADT for UIR or HR PC. These results support recent NCCN guideline updates, which include SBRT as a non-preferred option for higher risk men. Prospective validation would further strengthen the evidence basis behind these recommendations.

Highlights

Hypofractionated radiation therapy for prostate cancer is an appealing and increasingly adopted approach that has advantages from a radiobiologic, cost, and patient convenience standpoint [1,2,3,4]
Within study limitations, we found no difference in survival between stereotactic body radiotherapy (SBRT)+androgen deprivation therapy (ADT) and standard of care EBRT+ADT for unfavorable intermediate (UIR) or HR prostate cancer (PC)
SBRT has been minimally utilized in UIR and HIR prostate cancer between 2004 and 2016, there has been a significant rise in its use over this time (p for trend

Summary

Introduction

Hypofractionated radiation therapy for prostate cancer is an appealing and increasingly adopted approach that has advantages from a radiobiologic, cost, and patient convenience standpoint [1,2,3,4]. The ASTRO/ASCO/AUA societal guidelines do not currently recommend routine use of ultrahypofractionated radiation therapy for men with unfavorable risk prostate cancer, with a conditional recommendation against its use in men with high risk disease [9]. Since publication of those guidelines, the HYPO-RT-PC randomized trial [11] showed noninferiority of ultrahypofractionation in a cohort of intermediate and high risk men. The comparative efficacy of SBRT plus androgen deprivation therapy (ADT) compared to fractionated radiotherapy (EBRT) plus ADT in higher-risk prostate cancer is unknown

Methods

Results

Conclusion