ESTRO 2022 - Abstract Book

S952

Abstract book

ESTRO 2022

The purpose of this study was to evaluate the treatment outcomes and toxicity profile of patients with early glottic cancer who underwent hypofractionated radiation therapy (RT) with 3.5 Gy per fraction. Materials and Methods A retrospective review was performed of the medical records of 35 patients with early stage (T1-2N0M0) glottic cancer who underwent definitive RT. The dose fractionation scheme was 59.5 Gy in 17 fractions. The posterior commissure was excluded from the clinical target volume (CTV) for 26 (74.3%) patients without glottic lesions close to this region. Examples of radiotherapy plan are illustrated in the following figure (panel A, posterior commissure included in CTV; panel B, posterior commissure excluded from CTV).

Results With a median follow-up of 16.23 months (range, 6.82 to 67.15 months), no local, regional, or distant recurrence was reported. Acute hoarseness (65.7%), mucositis (68.6%), radiation dermatitis (60.0%) was frequent. One patient (2.9%) reported grade 3 acute toxicity (mucositis) and there was no grade 4-5 acute toxicity. There was no grade ≥ 3 late toxicities; however, grade 1 late intermittent hoarseness was frequent (45.7%). The receiver operative characteristic analysis revealed that mean hypopharyngeal dose was predictive for acute grade ≥ 2 mucositis (area under the curve 0.9314, 95% confidence interval 0.8524–1). The optimal threshold of mean hypopharyngeal dose for occurrence of acute grade ≥ 2 mucositis was 26.31 Gy, with a specificity and sensitivity of 83.3% and 88.2%, respectively. Conclusion Hypofractionated RT with fraction size of 3.5 Gy for early glottic cancer is safe and effective. The hypopharyngeal mean dose could predict the occurrence of grade ≥ 2 acute mucositis. The posterior commissure can be safely excluded from the CTV.

PO-1120 The potential value of MRI in response evaluation after primary (C-)RT for head and neck cancer

S. Mohamed 1,2 , J.K. Lilja-Fischer 3 , M. Hjørringgaard Madsen 4 , J.G. Eriksen 2,5

1 NCI, Cairo University, Dept. of Radiation Oncology, Cairo, Egypt; 2 Aarhus University Hospital, Dept. of Oncology, Aarhus, Denmark; 3 Aarhus University Hospital, Dept. of Head and Neck surgery, Aarhus, Denmark; 4 Aarhus University Hospital, Dept. of Neuro radiology, Aarhus, Denmark; 5 Aarhus University Hospital, Dept. of Experimental clinical oncology, Aarhus, Denmark Purpose or Objective To evaluate the value of routine MRI at 3 months after primary (chemo-)radiotherapy ((C-)RT), as an addition to 2 months' standard clinical evaluation for squamous cell carcinoma (SCC) of the larynx, pharynx, and oral cavity.