Presenter of 1 Presentation
A RANDOMIZED CLINICAL PHASE-III-TRIAL COMPARING SINGLE-HIGH DOSE FLASH-RADIOTHERAPY VERSUS CONVENTIONALLY FRACTIONATED RADIOTHERAPY IN CAT-PATIENTS WITH SQUAMOUS CELL CARCINOMA: EARLY STOPPING DUE TO LATE TOXICITY
Abstract
Background and Aims
Normal tissue-sparing property of FLASH-RT has been shown in various studies, including a dose-escalating trial with single-dose FLASH-RT (25-41Gy) in cat-patients. Results prompted us to design this prospective, randomized clinical phase-III-trial in cat-patients with spontaneous tumors, to compare single-high-dose FLASH-RT to a standard of care (SOC); with tumour control-rate at 1 year as primary endpoint (hypothesis= 95% with FLASH-RT versus 71% for SOC, alpha=0.05 and beta=0.2, 29 cats needed).
Methods
Ethic’s approval was obtained (ZH204/18) and cats with T1-T2 N0 carcinomas of the nasal planum were randomly assigned to 2 arms of electron radiation. Arm 1 used 10x4.8Gy (90%IDL), delivered in one week with a 6MeV linear accelerator, dose rate of 600MU/min. Arm 2 used 1x30Gy (89%IDL) with eRT6/Oriatron, delivered in 20ms using 3 pulses, instantaneous dose rate of 6.3x106Gy/s (mean dose rate 1700Gy/s).
Results
While acute side effects were mild to moderate and similar in both arms, the trial was prematurely stopped due an excess of maxillary bone necrosis which occurred 9-12 months after RT in 3/7 cats treated with FLASH-RT (43%), as compared to 0/9 cats in SOC. Regarding the primary endpoint, all cats were free of tumor progression at 1 year in both arms, but one tumor progression occurred later in FLASH-RT arm. Overall survival rates were similar in both arms, 690 days for SOC and 680 days for FLASH.
Conclusions
When compared to SOC, 1x30Gy-FLASH was beyond the maximal tolerated dose, causing severe late toxicity without better tumor control.
Acknowledgments: Krebsliga, KFS-4438-02-2018: Phase III clinical trial on cat patients
Author Of 1 Presentation
A RANDOMIZED CLINICAL PHASE-III-TRIAL COMPARING SINGLE-HIGH DOSE FLASH-RADIOTHERAPY VERSUS CONVENTIONALLY FRACTIONATED RADIOTHERAPY IN CAT-PATIENTS WITH SQUAMOUS CELL CARCINOMA: EARLY STOPPING DUE TO LATE TOXICITY
Abstract
Background and Aims
Normal tissue-sparing property of FLASH-RT has been shown in various studies, including a dose-escalating trial with single-dose FLASH-RT (25-41Gy) in cat-patients. Results prompted us to design this prospective, randomized clinical phase-III-trial in cat-patients with spontaneous tumors, to compare single-high-dose FLASH-RT to a standard of care (SOC); with tumour control-rate at 1 year as primary endpoint (hypothesis= 95% with FLASH-RT versus 71% for SOC, alpha=0.05 and beta=0.2, 29 cats needed).
Methods
Ethic’s approval was obtained (ZH204/18) and cats with T1-T2 N0 carcinomas of the nasal planum were randomly assigned to 2 arms of electron radiation. Arm 1 used 10x4.8Gy (90%IDL), delivered in one week with a 6MeV linear accelerator, dose rate of 600MU/min. Arm 2 used 1x30Gy (89%IDL) with eRT6/Oriatron, delivered in 20ms using 3 pulses, instantaneous dose rate of 6.3x106Gy/s (mean dose rate 1700Gy/s).
Results
While acute side effects were mild to moderate and similar in both arms, the trial was prematurely stopped due an excess of maxillary bone necrosis which occurred 9-12 months after RT in 3/7 cats treated with FLASH-RT (43%), as compared to 0/9 cats in SOC. Regarding the primary endpoint, all cats were free of tumor progression at 1 year in both arms, but one tumor progression occurred later in FLASH-RT arm. Overall survival rates were similar in both arms, 690 days for SOC and 680 days for FLASH.
Conclusions
When compared to SOC, 1x30Gy-FLASH was beyond the maximal tolerated dose, causing severe late toxicity without better tumor control.
Acknowledgments: Krebsliga, KFS-4438-02-2018: Phase III clinical trial on cat patients