Impact of COVID-19 pandemic on Carbon Ion Radiotherapy in Japan: a Japanese National Registry Study

Abstract

PurposeThis study aimed to investigate the impact of the COVID-19 pandemic on carbon ion radiotherapy (CIRT) in Japan by evaluating patient numbers and treatment trends from 2019–2022. Patients and MethodsData from five CIRT facilities were analyzed, encompassing a total of 13,224 patients treated over the 4-year period. Patient demographics, cancer types, treatment protocols, and adherence to national health insurance coverage were examined. The study period was divided into unaffected (2019), significantly affected (2020–2021), and post-stabilization (2022) phases, corresponding to progression of the pandemic. For monthly analysis, the period during which a state of emergency was declared by the Japanese government was defined as the pandemic period. ResultsProstate cancer comprised the majority of CIRT cases (62.4%), followed by hepatocellular carcinoma, bone and soft tissue tumors, locally advanced pancreatic cancer, and non-squamous cell carcinoma of the head and neck. Despite the pandemic, the annual reduction in CIRT patients remained <5%, suggesting treatment continuity. Analysis of monthly treatment figures revealed a significant reduction in the number of patients with non-prostate cancers treated during the state of emergency, while a reduction in the number of prostate cancer treatments was observed approximately 6 months later. Although the number of COVID-19 patients continued to increase after 2022, the number of patients receiving CIRT increased after the state of emergency was declared. ConclusionAlthough there was a reduction in monthly CIRT patient numbers during the COVID-19 pandemic, yearly analysis revealed that this amounted to <5%.