ESTRO 2025 - Abstract Book

S1008

Clinical – Head & neck

ESTRO 2025

Results:

Between 01/15 and 09/20, 100 OPC patients were treated. The median age was 63, with 69% diagnosed with HPV associated disease and 91% receiving concurrent chemotherapy. Most patients (80%) had stage III/IV disease per TNM 8th edition. At a median follow-up of 60 months (IQR: 42,8-80,8), 73 patients were alive, and 71% had no disease evidence. Three-year local control (LC) and progression-free survival (PFS) rates were 85% and 68%, respectively. Median PFS and overall survival (OS) were 107 months (95%CI 53.1-160.9) and 112 months (95%CI 81.1-96.8) ( Figure 2 ), respectively. Distant metastases (23%) were the primary pattern of failure, with 15% of local failure rate. Twelve out of 15 relapses were in-field (PTV-P1), and three were marginal. Average value of PTV-P2 dose and OralCavity_Dmean were 5698 cGy (SD: 462) and 4583 cGy (SD: 749), respectively. No significant correlation was observed between PTV-P2D95 nor OralCavity_Dmean and Grade (G) 2+ (p 0.22 and p 0,54) or G 3+ mucositis (p 0.37 and p 0.97), respectively. Conclusion: The omission of 10-mm expansion for CTV-P2 did not result in a detrimental effect on local failure. Future comparisons between the two delineation strategies are needed in order to explore the potential impact on toxicity and dosimetric parameters.

Keywords: oropharyngeal cancer, clinical target volume

References: 1. Grégoire V et al. Radiother Oncol. 2018