Normal tissue complication probability model predicting taste impairment in head and neck cancer patients: Evaluating the taste bud bearing tongue mucosa as a predictor

Background/Purpose: Taste impairment is a common yet complex toxicity of head and neck cancer (HNC) radiotherapy treatment that may affect quality of life of survivors. This study aimed to predict acute and late taste impairment using taste bud bearing tongue mucosa as a new taste-specific organ-at-risk compared to full oral cavity as identified in previous studies. Materials/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 new tongue mucosa structure was derived from the existing oral cavity structure in accordance with published guidelines. An auto-segmentation tool was developed and verified by comparison to manually delineated structures. The performance of the mean dose admitted to this new structure was evaluated with both univariable analysis and a refit of a reference NTCP model substituting the oral cavity with the tongue mucosa. Results: A total of 691 HNC patients were included. Good conformity between manually delineated and autosegmented structures was observed with no significant differences in mean dose (22.2 Gy vs. 22.1 Gy) or volume (20.7 cm3 vs. 20.3 cm3). Full oral cavity mean dose showed comparable effect size in univariable analysis compared to tongue mucosa mean dose. The NTCP model with tongue mucosa did not outperform the reference model with oral cavity for any evaluated time points. Conclusion: The tongue mucosa mean dose did not outperform the oral cavity mean dose in the logistic regression NTCP model predicting acute and late taste impairment.