Acute, late toxicities & early outcomes in children after proton therapy for head & neck malignancy

Abstract

Purpose or Objective To report acute and early late toxicities and early clinical outcomes following proton beam therapy (PBT) for paediatric/adolescent head and neck (HN) malignancies treated at our institute. Materials and Methods We retrospectively analysed prospectively maintained electronic records for all patients <25 years of age treated with PBT at our institute for HN malignancies between 2018-2020. All patients were treated with pencil beam scanning PBT with daily cone-beam CT (CBCT). Toxicity was assessed weekly on treatment and then at regular follow-up and graded according to CTCAE v5. All patients had post-treatment imaging to assess response at 12 weeks and repeat imaging was performed in those with suspicion of clinical recurrence. Results 48 patients <25 years of age were treated with PBT at our institute for HN malignancies during the study period. The median age at treatment was 14 years (range: 1-25 years). Patient, disease, and treatment characteristics are highlighted in table 1. After a median follow-up of 18 months (Range: 8-34 months), the actuarial 1-year overall survival, local control, and distant control rates for the entire cohort were 92%, 89%, and 94%, respectively. Five patients experienced an isolated local failure (3 RMS, 1 ES, and 1 other). Only 1 patient had a nodal recurrence and was surgically salvaged. Isolated distant failure . Conclusion Our BH technique results in sufficiently stable breath-holds for proton therapy. The BH proton technique resulted in a lower MHD than the BH photon technique in all patients. In the current cohort, BH proton therapy would have resulted in a clinically significant reduction of ≥ 2% in the life time risk of ≥ grade 4 acute coronary events in the majority of patients.