Dose Reduction to the Swallowing Apparatus and the Salivary Glands by De-Intensification of Postoperative Radiotherapy in Patients with Head and Neck Cancer: First (Treatment Planning) Results of the Prospective Multicenter DIREKHT Trial.

Marlen Haderlein,Claudia Scherl,Markus Hecht,Sebastian Lettmaier,Benjamin Frey,Rainer Fietkau,Stefan Speer,Sabine Semrau,Oliver Ott,Marco Kesting,Heinrich Iro

doi:10.3390/cancers12030538

Abstract

Aim: Evaluating radiotherapy treatment plans of the prospective DIREKHT trial (ClinicalTrials.gov, NCT02528955) investigating de-intensification of radiotherapy in patients with head and neck cancer. Patients and Methods: The first 30 patients from the DIREKHT trial of the leading study centre were included in this analysis. Standard treatment plans and study treatment plans derived from the protocol were calculated for each patient. Sizes of planning target volumes (PTVs) and mean doses to organs at risk were compared using the Student’s t-test with paired samples. Results: Mean PTV3 including primary tumor region and ipsilateral elective neck up to a dose of 50 Gy in the study treatment plans was 662 mL (+/− 165 mL standard deviation (SD)) and therefore significantly smaller than those of the standard treatment plans (1166 mL (+/− 266 mL SD). In the medial and inferior constrictor muscles, cricopharyngeal muscle, glottic and supraglottic laryngeal areas, arytenoid cartilages, contralateral major salivary glands highly significant dose reductions (p < 0.0001) of more than 10 Gy were achieved in study treatment plan compared to standard treatment plan. Conclusion: De-intensification of radiotherapy led to smaller planning target volumes and clinical relevant dose reductions in the swallowing apparatus and in the contralateral salivary glands.

Highlights

To date, there is only one prospective study [1] with a small sample size and some retrospective studies [2,3] investigating the possibility of treating ipsilateral elective neck nodes only in the Cancers 2020, 12, 538; doi:10.3390/cancers12030538 www.mdpi.com/journal/cancersCancers 2020, 12, 538 postoperative situation of head and neck cancer
There is evidence for dose–volume relationships linking the dose to the major salivary glands to a dry mouth and clear dose limits exist for the parotid gland [16]
There are several studies [17,18,19,20,21,22,23,24,25,26,27] that demonstrate a dose-volume-relationship between late dysphagia and the radiation dose delivered to specific parts of the swallowing apparatus

Summary

Introduction

There is only one prospective study [1] with a small sample size and some retrospective studies [2,3] investigating the possibility of treating ipsilateral elective neck nodes only in the Cancers 2020, 12, 538; doi:10.3390/cancers12030538 www.mdpi.com/journal/cancersCancers 2020, 12, 538 postoperative situation of head and neck cancer. The primary tumor region usually is treated with a dose up to 64–66 Gy [4,5,6]. The sole study investigating dose reduction in patients with postoperative situation of head andpostsurgical neck cancer. The primary is treated head and neck cancer undergoing radiotherapy (RT) istumor. Petersregion et al.usually [7] which showed with a dose up to Gy [4,5,6]. The sole study investigating dose reduction in patients with head that a minimal dose of 57.6 Gy should be applied even in low-risk patients. Risk classification was and cancer undergoing is patients [7] T4 which showed thatnerve a done byneck a point score leading postsurgical to a possibleradiotherapy inclusion of(RT)

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