Measuring Edema in Irradiated Head and Neck Cancer Patients

Abstract

Edema is a common side effect of radiotherapy for head and neck cancer. Systems have been developed to record and monitor changes that occur after radiotherapy. These lack the sensitivity to record edema in specific laryngo-pharyngeal structures. The aim of this study was to develop a rating scale to measure edema in the larynx and pharynx. This was an exploratory study to develop a new measure, with the help of an expert panel, assessing interrater and intrarater reliability. A consensus group developed the rating scale. Eleven structures and 2 spaces were identified as areas sensitive to the development of edema. The terms no, mild, moderate, and severe were used to describe the degrees of edema. The scale was piloted and then tested for interrater and intrarater reliability on 5 speech and language therapists. They viewed 25 nasendolaryngoscopic images (23 patients who had had radiotherapy and 2 healthy volunteers). The images were rated with the scale. This process was repeated 1 week later. Images were taken from patients with oral, oropharyngeal, nasopharyngeal, or laryngeal cancer. All had had radiotherapy or chemoradiotherapy. All raters were experienced in viewing larynges via nasendolaryngoscopy. The interrater reliability for scoring the edema rating scale was moderate (weighted kappa, 0.54). Lower levels of agreement were found for the tongue base, valleculae, pharyngeal walls, and anterior commissure. The intrarater reliability was very good (weighted kappa, 0.84). The edema rating scale can be scored with very good test-retest reproducibility and moderate levels of agreement between clinicians. Modifications to the method are suggested to increase interrater reliability.