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18F-FDG-PET in Guided Dose-Painting with Intensity Modulated Radiotherapy in Oropharyngeal Tumours: A Phase I Study (FiGaRO)

Research output: Contribution to journalArticlepeer-review

Original languageEnglish
JournalRadiotherapy and Oncology
Accepted/In press4 Nov 2020

King's Authors

Abstract

Background and purpose The FiGaRO trial assessed the feasibility and safety of using an FDG-PET-based dose-painting technique to deliver a radiotherapy (RT) boost to the FDG-avid primary tumour in patients with locally advanced high and intermediate risk oropharyngeal cancer. Materials and Method Patients underwent a planning 18FDG-PET-CT scan, immobilised in the treatment position, after one cycle of induction chemotherapy. The volume of persistent FDG-avidity in the primary tumour was escalated to 71.5Gy in30 fractions delivered using a simultaneous integrated boost Intensity Modulated RT (SIB-IMRT) technique. RT was delivered with concomitant Cisplatin following 2 cycles of induction chemotherapy. The primary outcome was the incidence of grade ≥3 late mucosal toxicity 12 months post-treatment, with an excess rate of >10% regarded as unacceptable. Results Twenty-nine patients were included and twenty-four were treated between 2014 and 2018, in two UK centres. Median follow-up was 36 months (range 4-56 months). Pre-defined planning target volume objectives and organ at risk dose constraints were met in all cases. There were no incidents of acute grade 4 toxicity. There were 4 cases of grade ≥3 mucosal toxicity at 12 months post-treatment (19.1%). There were no cases of persistent mucosal ulceration at 12 months. Overall survival at 3-years was 87.5%, 92.9% for intermediate and 70.0% for high risk patients. Conclusion Late toxicity rates, although higher than anticipated, are comparable to contemporary published data for standard dose chemo-IMRT. Results suggest improved 3y survival rates for high risk patients. This approach merits further investigation.

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