ESTRO 2024 - Abstract Book

S1312

Clinical - Head & neck

ESTRO 2024

Data for dysphagia at 6 and 12 months was available for 1,202 and 1,177 patients, respectively, approximately 62% of the cohort. The median GTV-CTV1 margin was 9.0 mm (IQR 0.0-9.7) for the patients treated in 2010-2012 using the old guidelines and 4.7 mm (IQR 4.0-5.5) for 2013-2015 using the updated guidelines. The severity of dysphagia did not differ significantly between the two treatment periods. Predictors for developing dysphagia at 6 months included female sex (Odds Ratio (OR) 1.6 CI95% [1.3-2.1]), smoking during treatment (OR 1.7 [1.3-2.2]), no radiosensitiser (OR 1.9 [1.2-3.1]), no chemotherapy (OR 1.6 [1.2-2.1]), and lnGTV (OR 1.6 [1.4-1.8]). At 12 months, the significant predictors were: female sex (OR 1.6 [1.2-2.2]), smoking (OR 1.9 [1.5-2.4]), no chemotherapy (OR 1.5 [1.1-2.0]), and lnGTV (OR 1.7 [1.4-1.9]). Forest plot of the parameters is presented in Figures 1 and 2 for 6- and 12-month dysphagia, respectively. The GTV-CTV1 margin was not a significant predictor for dysphagia at either 6 or 12 months. This finding is unexpected, as larger treatment volumes would intuitively be associated with increased toxicity. However, the current data does not support this, and the GTV volume seems to be the main geometrical component in the risk of dysphagia. Additional analysis involving planning target volume (PTV) margins did not alter these results. The observed effect at 6 months for patients not receiving nimorazole may be attributed to the limited number of patients in this group rather than a favourable biological response to dysphagia. This effect disappeared at 12 months.

The counterintuitive result of patients not receiving systemic treatment having a higher risk of dysphagia than those receiving systemic treatment remains unexplained.