Revisiting unnecessary larynx irradiation with whole-neck IMRT

Purpose: To determine if whole-neck intensity-modulated radiotherapy (IMRT) spares the larynx as well as techniques that match a conventional anterior-neck field to an IMRT plan superior to the larynx. Methods and Materials: This is a dosimetric study using the treatment planning image sets from 5 consecutively treated patients with node-positive squamous cell carcinoma of the oropharynx, all with gross disease above the larynx. We compared 3 techniques for irradiating the mid- and low-neck lymphatics: whole-neck IMRT, conventional anterior-neck field with split-beam matching, and conventional anterior-neck field with gradient matching. Prescription doses for the high-, intermediate-, and standard-risk planning target volumes were 70 Gy, 60 Gy, and 50 Gy, respectively. Results: The mean larynx dose was similar with all techniques with median values: whole-neck IMRT, 28 Gy (range, 17-30 Gy); conventional field with split-beam matching, 26 Gy (range, 21-33 Gy); conventional field with gradient matching, 30 Gy (range, 25-31 Gy). Conclusions: With meticulous attention to the details of contouring and treatment planning, it is possible to use whole-neck IMRT without increasing the risk of larynx dysfunction compared to techniques that block the larynx in a conventional anterior-neck field. We discuss the potential advantages of each technique in this article.