ESTRO 2025 - Abstract Book

S1088

Clinical – Head & neck

ESTRO 2025

Purpose/Objective: Osteoradionecrosis (ORN) affects up to 15-20% of previously irradiated head and neck cancer patients, based on current epidemiological data. Various conservative and surgical treatment approaches exist, with the combination of pentoxifylline, tocopherol, with or without clodronate (PENTOCLO) emerging as a promising non-invasive intervention due to its favorable toxicity profile. However, robust evidence from large-scale studies with extended follow-up on the efficacy of PENTOCLO remains limited. Furthermore, its role as a first-line or second-line treatment, particularly administered after ORN progression from hyperbaric oxygen therapy (HBOT), has not been investigated. Material/Methods: This retrospective single-center cohort study analyzed head and neck cancer patients with documented ORN managed at the Adult Radiation Late Effects Clinic (ARLEC) from 2003 to 2020. Inclusion criteria included patients with at least 2 years of follow-up post-radiation therapy who received PENTOCLO during their toxicity treatment course. PENTOCLO was administered as a first-line, second-line, or third-line therapy. Other therapeutic options included HBOT and ORN surgery (mandibular resection and sequestrectomy). Clinical outcomes, defined as ORN improvement, stability, and progression, were extracted from electronic medical records. Results: A total of 140 patients were included, with the majority being male (69%) and treated primarily for oral cavity or oropharyngeal carcinomas (86%). Definitive radiation therapy was delivered to 62% of patients, with a median dose of 70 Gy. Among the cohort, 94% demonstrated clinical improvement or stabilization of ORN following PENTOCLO administration. However, 39% eventually required additional interventions, including HBOT or surgery, due to progression. One case utilized PENTOCLO as a third-line therapy following HBOT and surgery. Seven patients experienced tumor recurrence prior to ORN diagnosis, and the symptoms/outcomes were dissociated from local failure. The 2-year and 3-year deterioration-free rates were 67% and 60%, respectively for patients receiving PENTOCLO as a first-line therapy. Among patients who received PENTOCLO as second- or third-line therapy, the 2 year and 3-year progression-free rates were 77% and 62%, respectively. The rate of ORN deterioration was not statistically significant when PENTOCLO was used as the initial treatment or as second/third-line treatment (p = 0.537).