ESTRO 2023 - Abstract Book

S22

Saturday 13 May

ESTRO 2023

Conclusion Proton beam therapy in the adjuvant setting was well tolerated with only low-grade side effects concerning gastrointestinal symptoms, lymphedema and pain. Overall quality of life was impaired at baseline, but patients were able to recover to values comparable to norm population two years after proton therapy. Larger studies are needed to confirm whether the benefit of proton therapy translates into a clinical effect. Sexual dysfunction remains an important issue.

Mini-Oral: TCP/NTCP modelling and prediction

MO-0055 Prediction of radiation-induced taste loss with taste bud bearing tongue mucosa in HNC patients H. Neh 1 , S.P. de Vette 1 , H. Chu 1 , N.M. Sijtsema 1 , P.M. van Ooijen 1 , R.J. Steenbakkers 1 , J.A. Langendijk 1 , L.V. van Dijk 1 1 University Medical Center Groningen, Radiotherapy, Groningen, The Netherlands Purpose or Objective Taste loss is a common yet complex toxicity of head and neck cancer (HNC) radiotherapy treatment. Prediction prior to treatment is important to minimize taste loss and maintain quality of life of HNC survivors. Radiation-induced toxicities are commonly predicted by normal tissue complication probability (NTCP) models. Taste NTCP prediction is based on the dose to the oral cavity. Stieb et al. (2021) proposed the taste bud bearing tongue mucosa as a new taste loss predictor. This project aimed to test the prediction of taste loss at 6 months after HNC radiotherapy with auto-segmented tongue mucosa compared to full oral cavity as identified in previously developed NTCP models. Materials and Methods Included HNC patients were treated with curative radiotherapy between 2007 and 2022. The endpoint was patient-rated moderate-to-severe taste loss scored with the EORTC QLQ-H&N35. The previously published reference NTCP model included the oral cavity mean dose, combined parotid gland mean dose and age (Bosch et al. 2021). The new tongue mucosa structure was derived from the existing oral cavity structure by 1) creating an inner rim of 5 mm of the oral cavity structure and 2) trimming the posterior, anterior and inferior regions in accordance with Stieb et al. guidelines (see Figure). The performance of the mean dose admitted to this new structure was compared to the full oral cavity with both univariable analysis and a refit of the reference NTCP model substituting the tongue mucosa for the oral cavity structure. Figure 1: Centred sagittal view of a CT with oral cavity structure delineated in green and auto-segmented taste bud bearing tongue mucosa structure delineated in red.