ESTRO 2024 - Abstract Book

S1279

Clinical - Head & neck

ESTRO 2024

occurrence or exacerbation of hypothyroidism, classified as at least Grade 1 according to CTCAE (Common Terminology Criteria for Adverse Events), and recorded the corresponding levothyroxine dosage. Statistical analysis was carried out using MedCalc v20.013.

Results:

We conducted an analysis involving 57 patients (31 males and 26 females). The median age at the time of diagnosis was 70 years (range: 48-96 years). Among these patients, 27 were categorized in the RT-IT group, while the remaining 30 belonged to the IT group. We observed that the occurrence or worsening of hypothyroidism was more prevalent in the RT-IT group, with 11 patients affected, in contrast to the IT group where only 7 patients experienced this condition. Furthermore, among all patients, hypothyroidism was more common in individuals older than 70 years compared to their younger counterparts (p=0.013). The necessity to prescribe levothyroxine or increase its dosage was significantly higher in the RT-IT group compared to the IT group (p<0.001). Additionally, patients who received any form of neck RT had a higher likelihood of requiring levothyroxine (p=0.017). We also noticed a trend suggesting that thyroid dysfunction tended to occur earlier in the RT-IT group compared to the IT group, although the difference was not statistically significant (3.5 months vs 7 months, P = 0,0505). Finally, within the RT-IT group, the incidence or worsening of hypothyroidism correlated with higher tDmean values (p<0.001), increased tV50 (p<0.001), and greater tV60 (p=0.009).

Conclusion:

For patients diagnosed with HNSCC receiving IT, the delivery of RT raises the likelihood of hypothyroidism development or worsening, while also shortening the time frame to its onset. Moreover, this risk is linked to the volumes of the thyroid exposed to 50 Gy (tV50) and 60 Gy (tV60). Consequently, it is crucial to offer comprehensive counseling and diligently monitor thyroid function in the post-treatment follow-up of these patients.

Keywords: Hypothyroidism, Immunotherapy

1303

Mini-Oral

Prediction models for treatment outcome in nasopharyngeal carcinoma patients

Guanzhi Zhou 1,2 , Nanna M. Sijtsema 1 , Yan Li 1 , Arjen van der Schaaf 1 , Lisanne V. van Dijk 1 , Yingrui Shi 2 , Pei Yang 2 , Johannes A. Langendijk 1 1 University Medical Center Groningen, Radiotherapy, Groningen, Netherlands. 2 Hunan Cancer Hospital, The Department of Radiation Oncology, Changsha, China

Purpose/Objective: