Sunnybrook Odette Cancer Centre, Toronto, Canada.
High dose-rate (HDR) brachytherapy is most commonly administered as a boost in two or more fractions combined with external beam radiotherapy (EBRT). Our purpose is to compare outcomes with a single fraction HDR boost to that with a standard fractionated boost in intermediate risk prostate cancer.
Results of two sequential phase II clinical trials are compared. The Single Fraction protocol consists of 15Gy HDR in one fraction followed by 37.5Gy EBRT in 15 fractions over 3weeks; the Standard Fractionation protocol consisted of two HDR fractions each of 10Gy, 1week apart, followed by 45Gy EBRT in 25 fractions. Patients had intermediate risk disease, and were well balanced for prognostic factors. Patients were followed prospectively for efficacy, toxicity and health-related quality of life (Expanded Prostate Index Composite). Efficacy was assessed biochemically using the Phoenix definition, and by biopsy at 2years.
The Single Fraction protocol accrued 123 patients and the Standard Fractionation protocol, 60. With a median follow-up of 45 and 72months, respectively, the biochemical disease-free survival was 95.1% and 97.9% in the Single and Standard Fractionation trials (p=0.3528). Two-year prostate biopsy was positive in only 4% and 8%, respectively. There was no difference in late urinary or rectal toxicity rates, or in health-related quality of life between the two protocols.
The Single Fraction HDR protocol results in high disease control rate and low toxicity similar to our previous protocol using two HDR insertions, with significant savings in resources. While mature results with longer follow-up are awaited, a single 15Gy may be considered as a standard fractionation regimen in combination with EBRT for men with intermediate risk disease.
Written by:
Morton G, Loblaw A, Cheung P, Szumacher E, Chahal M, Danjoux C, Chung HT, Deabreu A, Mamedov A, Zhang L, Sankreacha R, Vigneault E, Springer C. Are you the author?
Reference: Radiother Oncol. 2011 Sep 14. Epub ahead of print.
doi: 10.1016/j.radonc.2011.08.022
PubMed Abstract
PMID: 21924511
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