Carbon ion radiotherapy (CIRT) has several advantages in cancer treatment. However, the dose of CIRT that the normal esophagus can tolerate is still unknown. Hence, we aimed to evaluate the safety and effectiveness of definitive CIRT for cT1bN0M0 esophageal squamous cell carcinoma (ESCC).
CIRT without chemotherapy was administered to patients with ESCC in 12 fractions over 3 weeks. The total radiation dose was escalated from the initial dose of 43.2 Gray relative biological effectiveness (Gy [RBE]) in 5% increments up to 50.4 Gy (RBE). The primary endpoints were treatment-related acute toxicity and tumor response to CIRT. The secondary endpoints were late toxicity, overall survival (OS), local tumor control (LC), and disease-free survival (DFS) rates.
Thirty patients were enrolled. The median follow-up duration was 86.7 months. Grade 3 acute esophagitis was present in two patients each, and Grade 3 neutropenia and lymphopenia in one patient each. Twenty-five patients (83%) achieved a complete response. Local recurrence was observed in 14 patients (46.7%). Four of 5 patients (80%) who received 43.2 Gy (RBE) and 10 of 25 patients (40%) who received 45.6 Gy (RBE) or more had local recurrence. The OS, LC, and DFS rates at 5 years were 80.0%, 69.3%, and 62.6%, respectively.
The results suggest that definitive short-course CIRT is a minimally invasive and effective treatment for cT1bN0M0 ESCC.
Copyright © 2023. Published by Elsevier Inc.
