Does Dose to an Oral Mucosa Organ at Risk Predict the Duration of Grade 3 Mucositis after Intensity-modulated Radiotherapy for Oropharyngeal Cancer?

Various methods have been described to delineate the oral mucosa organ at risk (OAR). This study examined whether dosimetric parameters derived from four different OARs correlated to the duration of acute grade 3 mucositis (G3M) in patients with oropharyngeal carcinoma. In total, 66 patients were included in this study. The duration of CTCAE version 3 G3M and the duration of strong opiate use were prospectively recorded, together with six patient factors. In addition, for each OAR the following dose parameters were derived: mean dose, V55, V50, V45, V40 and V30. No statistically significant correlation of version 3 G3M or duration of strong opiate use was noted with the tested parameters. However, a trend towards significance between duration of strong opiate use and pre-treatment weight was observed (P = 0.053), reaching statistical significance on subsequent linear regression. This study failed to show a relationship between dosimetric parameters derived from four oral mucosa OARs and the duration of CTCAE version 3 G3M or duration of opiate use, potentially suggesting serial rather than parallel radiobiological phenomena. The utility of CTCAE version 4 G3M as an end point requires further investigation given its potential relationship to pre-treatment weight.