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Updated: Feb 9, 2026

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Published on: July 3, 2014
The Advantage of FLASH Radiotherapy Confirmed in Mini-pig and Cat-cancer Patients
Marie-Catherine Vozenin1, Pauline De Fornel2, Kristoffer Petersson3,4
1Radio-Oncology Laboratory, Department of Radiation Oncology, Lausanne University Hospital, Lausanne, Switzerland. marie-catherine.vozenin@chuv.ch.
Purpose:
Previous studies using FLASH radiotherapy (RT) in mice showed a marked increase of the differential effect between normal tissue and tumors. To stimulate clinical transfer, we evaluated whether this effect could also occur in higher mammals.
Experimental Design:
Pig skin was used to investigate a potential difference in toxicity between irradiation delivered at an ultrahigh dose rate called "FLASH-RT" and irradiation delivered at a conventional dose rate called "Conv-RT." A clinical, phase I, single-dose escalation trial (25-41 Gy) was performed in 6 cat patients with locally advanced T2/T3N0M0 squamous cell carcinoma of the nasal planum to determine the maximal tolerated dose and progression-free survival (PFS) of single-dose FLASH-RT.
Results:
Using, respectively, depilation and fibronecrosis as acute and late endpoints, a protective effect of FLASH-RT was observed (≥20% dose-equivalent difference vs. Conv-RT). Three cats experienced no acute toxicity, whereas 3 exhibited moderate/mild transient mucositis, and all cats had depilation. With a median follow-up of 13.5 months, the PFS at 16 months was 84%.
Conclusions:
Our results confirmed the potential advantage of FLASH-RT and provide a strong rationale for further evaluating FLASH-RT in human patients.See related commentary by Harrington, p. 3.
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