ESTRO 2025 - Abstract Book

S927

Clinical – Head & neck

ESTRO 2025

Conclusion: In-field failures, constituting 61% of rNPC patient recurrences, were predominantly due to intra-tumoral treatment resistance. Future efforts should focus on confirming and modifying the biological nature to combat this resistance. Marginal failures were chiefly attributed to inaccurate post-IC GTV delineation. Recurrence-prone structures correlate with tumor regression sites, indicating that the current de-escalation scheme requires careful reassessment, particularly when considering shrinkage from areas such as the oropharynx, sphenoidal sinus, ethmoid sinus, and choanae.