S577
Clinical – Head & neck
ESTRO 2026
Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, Hong Kong
Purpose/Objective: Motor dexterity dysfunction is an under-recognized neurological sequela in nasopharyngeal carcinoma (NPC) survivors. We aim to evaluate the relationship of chemotherapy dose and radiation dose factors with We enrolled 190 NPC survivors who completed definitive intensity-modulated radiotherapy (IMRT). Motor dexterity was assessed using Grooved Pegboard Test (GP). Raw scores for both dominant and non-dominant hands were normalized to age and educational level using published normative data and outputted as standardized Z-scores. For 105 cases with retrievable brain MRI, motor-related regions of this late complication. Material/Methods: interest (ROIs), including bilateral precentral and postcentral gyri, brain stem, spinal cord, cerebellum, thalamus and striata, were auto-segmented using FreeSurfer pipeline (Version 8.0.0 for MacOS). All ROIs were centrally reviewed and manually edited by a radiation oncologist. Associations between motor dexterity outcomes with cisplatin dose or radiation dose-volume metrics were analyzed. Results: The median post-IMRT follow-up duration was 7.0 years (range, 1.0-13.6). The median age was 56 (range, 22-77). Most patients had T3 (61.1%) and N2 (67.9%) disease (AJCC 8th edition). 86.3% of patients received concurrent chemotherapy.NPC survivors exhibited significant impairments in GP Z-scores compared with normative data (median -0.3, Wilcoxon rank-sum test p<0.001 for both hands). The proportion of patients with GP Z-scores of <-2 were 22.1% and 18.9% for the dominant and nondominant hand, respectively.The dominant and nondominant precentral gyri received average Dmax of 4.4Gy and 4.0Gy respectively. Higher maximum (Dmax) and near-maximum (D1%) doses to the nondominant precentral gyrus were significantly associated with poorer nondominant hand GP Z- scores (Spearman ρ =-0.24, p=0.014; ρ =-0.23, p=0.021, respectively). Similarly, Dmax and D1% to the dominant precentral gyrus were negatively correlated with dominant hand GP Z-scores ( ρ =-0.21, p=0.035; ρ =- 0.21, p=0.028, respectively).
Patients who received higher cumulative cisplatin dose had poorer GP Z-scores in both the dominant hand (Jonckheere-Terpstra test p<0.001) and nondominant hand (p=0.028). For both hands, there was a median Z- score difference of >1.3 between those who received 450-600mg/m^2 of cisplatin and those who received 0- <150mg/m^2; a difference equivalent to ~42 years of age-related motor dexterity decline from population data.
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