ONE SHOT - single shot radiotherapy for localized prostate cancer: study protocol of a single arm, multicenter phase I/II trial

Abstract

BackgroundStereotactic body radiotherapy (SBRT) is an emerging treatment alternative for patients with localized prostate cancer. Promising results in terms of disease control and toxicity have been reported with 4 to 5 SBRT fractions. However, question of how far can the number of fractions with SBRT be reduced is a challenging research matter. As already explored by some authors in the context of brachytherapy, monotherapy appears to be feasible with an acceptable toxicity profile and a promising outcome. The aim of this multicenter phase I/II prospective trialis to demonstrate early evidence of safety and efficacy of a single-fraction SBRT approach for the treatment of localized disease.MethodsPatients with low- and intermediate-risk localized prostate cancer without significant tumor in the transitional zone will be treated with a single SBRT fraction of 19 Gy to the whole prostate gland with urethra-sparing (17 Gy). Intrafractional motion will be monitored with intraprostatic electromagnetic transponders. The primary endpoint of the phase I part of the study will be safety as assessed by CTCAE 4.03 grading scale, while biochemical relapse-free survival will be the endpoint for the phase II. The secondary endpoints include acute and late toxicity, quality of life, progression-free survival, and prostate-cancer specific survival.DiscussionThis is the first multicenter phase I/II trial assessing the efficacy and safety of a single-dose SBRT treatment for patients with localized prostate cancer. If positive, results of ONE SHOT may help to design subsequent phase III trials exploring the role of SBRT monotherapy in the exclusive radiotherapy treatment of localized disease.Trial registrationClinicaltrials.gov identifier: NCT03294889; Registered 27 September 2017.

Single-Fraction Stereotactic Body Radiation Therapy: A Paradigm During the Coronavirus Disease 2019 (COVID-19) Pandemic and Beyond?

“…A multi-center phase I/II study assessing the toxicity and efficacy of single-fraction SBRT of 19 Gy in patients with low- to intermediate-risk prostate cancer is currently underway. 61 …”

Harnessing the potential of multimodal radiotherapy in prostate cancer

“…Outcomes of therapy using convenNonal fracNonaNon plateau once paNents are treated with >78 Gray (276), and so the strategy has now moved towards delivery of hypofracNonated radiotherapy (277). SBRT to the prostate gland in the localized disease se{ng is the culminaNon of hypofracNonaNon, and single-fracNon doses of SBRT to the prostate gland are now being invesNgated (278). Single fracNon doses of irradiaNon to the prostate have been asempted in the past using high dose-rate brachytherapy, which was associated with high biochemical control rates, parNcularly in paNents with low-risk and intermediate-risk prostate cancer, and low complicaNon rates (279)(280)(281).…”

Focal salvage treatment for radiorecurrent prostate cancer: A magnetic resonance-guided stereotactic body radiotherapy versus high-dose-rate brachytherapy planning study

“…However, the different treatment setting with different OAR constraints makes it hard to extrapolate these results to our study. Currently, Zilli et al are investigating the delivery of a single 19 Gy dose to the whole prostate gland and two-thirds of the seminal vesicles with urethra sparing (down to 17 Gy) in a primary setting [17] , [18] . For bladder and rectum constraints, they use V20Gy < 1 cm 3 .…”

“…However, delivery of a single 19 Gy dose to a focal recurrent tumor using a volumetric modulated arch therapy (VMAT)-like technique resembles SBRT. Several studies on ultra-hypofractionated and single session radiotherapy for prostate cancer use only high-dose to low-volume constraints, thereby showing low toxicity rates [18] , [22] , [23] , [24] . Accordingly, we argue that D1cm 3 is a sensible and important parameter allowing for comparison between the two treatment modalities.…”