ESTRO 2025 - Abstract Book

S995

Clinical – Head & neck

ESTRO 2025

Conclusion: Online ART for NPC is clinically feasible and offers significant dosimetric benefits for targets and OARs.

Keywords: Online Adaptive Radiotherapy, Dosimetric Benefits

1790

Digital Poster Hyperfractionated chemoradiotherapy in locally-advanced unresectable head and neck squamous cell carcinoma: a prospective study Ali Kazemian, Marzieh Sheikh, Mahdi Aghili, Mohammad Babaei, Reza Ghalehtaki Radiation Oncology, Tehran University of Medical Sciences, Tehran, Iran, Islamic Republic of Purpose/Objective: Locally-advanced unresectable head and neck squamous cell carcinoma (LAHNSCC) is a challenging situation in radiation oncology with a limited chance of cure and high chance of local failure. We tried to assess the role of hyperfractionated twice-daily radiotherapy with concurrent chemotherapy in unresectable LAHNSCC. Material/Methods: This was a single arm clinical trial. Patients with biopsy proven SCC located in the mucosal surfaces of the head and neck that was not resectable with acceptable morbidity were included. Those with limited performance status or inability to tolerate chemotherapy were excluded. Our IRB and ethics committee (IR.TUMS.IKHC.REC.1400.059) approved our study design. Patients were treated with conformal RT twice-a-day to 70-75 Gy in 56-60 fractions in 28-30 days for 5 days a week. Concurrent chemotherapy was done using weekly intravenous cisplatin (30-35mg/m2) for 5-6 cycles. Induction chemotherapy was allowed but consolidation was not. First evaluation was done using at 4 6 weeks after RT termination. Patients with residual disease were consulted for salvage surgery. The primary endpoint was clinical response at 3-months post-radiotherapy and secondary endpoints included toxicity, overall and progression and local-recurrence free survival. Results: Between 2021 and 2023, 20 patients were recruited but only 15 have completed the planned treatment course and were entered in final analysis. The location of primary tumor was tongue in 5, oropharynx in 4 (HPV-negative), other oral cavity subsites in 4 and hypopharynx in 2. Eleven patients were male and the mean age was 49.3 (SD: 13.51). Nine patients (60%) underwent 3DRT and 6 (40%) IMRT. The median radiotherapy fractions was 56 (IQR:4). 47% of the patients had a RT interruption (median: 2 days). The median chemotherapy cycles was 5. 40% of patients had chemotherapy interruptions. Only two patients (13%) had received induction chemotherapy. In terms of response to treatment, 4 (27%) showed complete response, 9 (60%) had partial response, and 2 (13%) had progression in the 4-6 week follow-up. Two patients with partial response who had residual disease underwent salvage surgery with a negative margin. At 3-month, 6 (40%) patients had controlled disease and 9 (60%) had recurrence or progression or persistent residual disease. All of these cases underwent systemic treatment. Subacute mucositis was present in 2 (13.3%) after 3 months. Subacute mucositis and acute dermatitis was significantly lower in the IMRT group. Conclusion: This study showed that hyperfractionated chemoradiotherapy is tolerable with a promising efficacy and should be tested using IMRT in larger phase II-III randomized trials.

Keywords: Head and Neck SCC, Altered Fractionation