ESTRO 2025 - Abstract Book

S1014

Clinical – Head & neck

ESTRO 2025

Material/Methods: In this prospective, single-arm, observational cohort study, NPC patients undergoing RT with curative intent who were initially normosmia by olfactory identification test were recruited during 2023-2024. Patients with pre-existing hyposmia or tumor involvement at the olfactory groove were excluded. Olfactory function, visual analog scale (VAS), QoL using EORTC QLQ-C30 and EORTC QLQ-H&N35 questionnaires, and rhinosinusitis incidence were assessed before treatment, after IC (if administered), immediately post-RT, and at three- and six-month post-RT. The dose volume parameters of the olfactory bulbs and the cribriform plate were evaluated. The calculated sample size was 41 patients. Results: As of October 2024, 31 patients were recruited. Eighteen patients have completed RT and were analyzed. The median follow-up time of the analyzed group was 8.5 months from study enrollment and 4.4 months from RT completion. Thirty-nine percent of patients presented with T3-T4. IC was administered to 88.9% of patients. Most patients (94.4%) received intensity-modulated radiotherapy 70 Gy over 30-35 fractions with platinum-based CRT. The overall incidence of post-treatment hyposmia was 27.8%. Post-IC hyposmia incidence was 18.8%. The cumulative hyposmia incidence was 16.7% immediately post-RT and 21.4% at three months. All patients (N=3) who had post-RT hyposmia showed no recovery at their 6-month follow-up. Clinically and radiographically-confirmed rhinosinusitis occurred in 66.7% of patients, with no significant difference between normosmia and hyposmia groups (p=0.615). The mean of the worst score at any timepoint of QoL in the sensory problems domain was significantly worse in the hyposmia group compared to the normosmia group (73.3+19 vs 52.6+9.2, p=0.006). No other QoL domains and VAS showed significant differences between the two groups. There were no significant differences in radiation dose-volume parameters and olfactory bulb volumes between groups (p>0.05).

Conclusion: Approximately one-fourth of NPC patients developed hyposmia following radiotherapy, while two-thirds experienced rhino sinusitis. Olfactory dysfunction was primarily detected immediately post-RT and showed no recovery at 6-month follow-up. Hyposmia was associated with significantly worse sensory QoL. Longer follow-up time is warranted, and further intervention, e.g., olfactory rehabilitation, might be considered in those with persistent hyposmia.

Keywords: Nasopharyngeal carcinoma, olfactory function