Michael Cardoso MBBS , Matthew Richardson BMedRadSc , Phillip Chlap MSc , Sarah Keats BSc , Alan Glyde BSc , Sankar Arumugam PhD , David Pryor MBBS , Joseph Bucci MBBS , Jarad Martin PhD , Mark Sidhom MBBS
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引用次数: 0
Abstract
Purpose
Delayed genitourinary (GU) toxicity is reported following definitive stereotactic body radiation therapy (SBRT) for prostate cancer in 15% to 30% of patients. The purpose of this study is to investigate whether there is a relationship between radiation dose to the bladder and urethra and GU toxicity grade ≥ 2 (National Cancer Institute Common Terminology Criteria for Adverse Events 4.0) in patients treated with SBRT.
Methods and Materials
PROstate Multicenter External beam radioTHErapy Using Stereotactic boost was a phase 2 multicenter trial exploring an SBRT boost of 19 to 20 Gy in 2 fractions to the prostate combined with fractionated external beam radiation therapy as a virtual high-dose-rate brachytherapy boost for patients with prostate cancer. Several bladder and urethral constraints were mandated prospectively. Bladder and the urethral planning organ at risk volume (PRV) dosimetry was correlated with physician-reported GU toxicity for patients ≥ 6 months following SBRT. An association between prior transurethral resection of the prostate (TURP) and urinary toxicity was also examined. Univariant and multivariate analyses were performed.
Results
Of the 151 patients, 87 had complete dosimetric data, and these patients were included in this analysis. In this cohort, 19.5% experienced grade ≥ 2 GU toxicity more than 6 months after stereotactic radiation therapy. On univariate analysis, prostatic urethral length, urethral PRV volume, bladder D2 cc, D5 cc, D10 cc, D15 cc, and bladder V8 were predictive of GU toxicity (all P < .05). In the 14 patients who had prior TURP, 6 (43%) experienced GU toxicity compared with 15% for those without prior TURP (P = .015). Multivariate analysis showed that prostatic urethral length, urethral PRV volume, bladder 10 cc, and bladder 15 cc remained statistically significant factors predicting GU toxicity.
Conclusions
Prostate SBRT delivered as a virtual high-dose-rate boost is well tolerated overall. However, delayed GU toxicity is experienced by a significant minority of patients. Additional bladder constraints including D10 cc < 17 Gy and D15 cc < 15 Gy may further reduce the risk of delayed GU toxicity. Prior TURP may be a plausible additional risk factor.
期刊介绍:
The purpose of Advances is to provide information for clinicians who use radiation therapy by publishing: Clinical trial reports and reanalyses. Basic science original reports. Manuscripts examining health services research, comparative and cost effectiveness research, and systematic reviews. Case reports documenting unusual problems and solutions. High quality multi and single institutional series, as well as other novel retrospective hypothesis generating series. Timely critical reviews on important topics in radiation oncology, such as side effects. Articles reporting the natural history of disease and patterns of failure, particularly as they relate to treatment volume delineation. Articles on safety and quality in radiation therapy. Essays on clinical experience. Articles on practice transformation in radiation oncology, in particular: Aspects of health policy that may impact the future practice of radiation oncology. How information technology, such as data analytics and systems innovations, will change radiation oncology practice. Articles on imaging as they relate to radiation therapy treatment.