Single-Center Prospective Trial Investigating the Feasibility of Serial FDG-PET Guided Adaptive Radiation Therapy for Head and Neck Cancer

Abstract

We investigated in a single-center prospective trial (NCT03376386) the use of serial fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT) to determine the boost dose and to guide boost segmentation in head and neck cancer. Patients were eligible when treated with curative radiation therapy with or without systemic treatment for T2-4 squamous cell carcinoma of the hypopharynx, larynx, or oropharynx (20 patients in total). FDG-PET/CT scans were made at baseline and for redelineation and replanning at the end of weeks 2 and 4 of radiation therapy. The metabolically active part of the primary tumor received a 4 Gy boost on top of the 70 Gy baseline dose per partial metabolic response. The study would be considered feasible when ≥80% of adaptations were successful and no Common Terminology Criteria for Adverse Events grade ≥4 acute toxicity occurred. One patient received 70 Gy after complete metabolic response in week 2, and 12 patients received 78 Gy because of partial metabolic response at weeks 2 and 4. Seven patients received 74 Gy, either because of complete metabolic response at week 4 (n = 3) or a missed FDG-PET/CT (n = 4). The patients missed their FDG-PET/CT scans because they did not fast (n = 2) or at patients' request (n = 2). In addition to the 4 missed FDG-PET/CT scans, 2 adaptive plans could not be finished successfully owing to logistical problems. In total, 85% of adaptations were completed correctly. No patient experienced grade ≥4 toxicity, and 40% had grade 3 dysphagia (tube feeding) during treatment. This decreased at 12 weeks posttreatment to 20%. This prospective trial demonstrates the feasibility of serial FDG-PET/CT scans for dose escalation and patient selection.