(A609) Proton vs Carbon-Ion therapy: Which particle therapy is best in head and neck cancer treatment

Introduction: Charged particle therapy, including proton therapy (PT) and carbon ion therapy (CIRT), is recognized for its precision in delivering radiation with minimal damage to surrounding tissues. The relative advantages of PT versus CIRT in head and neck cancer treatment remain unclear. Hence, our main goal is to evaluate therapeutic efficacy and safety when utilizing PT versus CIRT.

Methods: A systematic search was conducted across PubMed, Embase and Web of Science for studies assessing PT and CIRT outcomes, with a focus on both primary and reirradiation settings. A random-effects meta-analysis was performed to estimate pooled efficacy and safety outcomes for each treatment modality.

Results: From 1431 identified articles, 66 studies met the inclusion criteria, comprising 4,731 patients (2766 treated with PT and 1965 with CIRT). For primary radiation, PT demonstrates higher 2-year overall survival (OS: 87.1% vs. 82.7%) and disease-free survival (DFS: 85.4% vs. 70.5%) compared to CIRT, with comparable local control rates (LCR: PT 84.5% vs. CIRT 86.5%). In reirradiation setting, CIRT demonstrated better 2-year OS (75.6% vs. 47.0%) and LCR (59.2% vs. 54.1%) compared to PT. For acute toxicity (AT), CIRT exhibited similar grade 1-2 AT events (91.2% vs. PT 87.5%) and a greater frequency of grade ≥3 AT (29.2% vs. PT 21.7%). In terms of late toxicity (LT), both therapies show similar rates of grade 1-2 LT events (PT 79.7% vs. CIRT 81.1%); however, severe grade ≥3 LT is more common with PT (43.7%) compared to CIRT (26.9%).

Conclusions: PT demonstrated superior efficacy in primary radiation, with higher 2-year OS and DFS, while CIRT excelled in reirradiation with better 2-year OS. CIRT had a higher incidence of grade ≥3 AT but lower grade ≥3 LT compared to PT.