Proton beam therapy for mediastinal Hodgkin lymphoma: A prospective study of clinical efficacy and safety.

in Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology by Kateřina Dědečková, Michal Andrlik, Heidi Móciková, Lucia Kaliská, Simona Zapletalová, Jiří Kubeš, Sarah Al-Hamami, David J Cutter, Georgios Ntentas, Vladimír Vondráček, Barbora Ondrová, Jana Marková, Ľubica Gahérová, Lekaá Mohammadová, Vít Procházka, Jozef Michalka, Alice Sýkorová, Juraj Ďuraš, Jan Kořen, Matěj Navrátil, Michaela Vařejková, Tomáš Doležal, Jana Prausová,

TLDR

  • Proton beam therapy using pencil beam scanning is a safe and effective treatment for mediastinal Hodgkin lymphoma, with high rates of disease-free survival, overall survival, and local control, and minimal toxicity.

Abstract

Proton beam therapy using pencil beam scanning is an advanced radiotherapy technique that utilises proton beams to precisely target tumours. It is known for its enhanced ability in sparing healthy tissue and potentially reducing toxicity. Clinical experience with pencil beam scanning in the treatment of mediastinal Hodgkin lymphoma remains limited. This study aimed to evaluate the toxicity and outcomes of a prospectively observed cohort. A total of 162 patients were irradiated between May 2013 and December 2020, with a median age of 32 years (range: 18.4-79.2) and followed up until April 2024. The median applied dose was 30 GyE (range: 20-40). Deep inspiration breath hold was used in 146 patients to enhance targeting precision. The disease-free survival, overall survival and local control rates were 95.1 %, 98.8 % and 98.8 %, respectively. The median follow-up was 59.1 months (range: 4-120.1). The most common acute toxicities observed were oesophageal and skin toxicity. Grade 1 oesophageal mucositis occurred in 76 patients (47 %), grade 2 in 16 patients (10 %). Dermatitis of grade 1 and 2 was observed in 65 (40 %) and 4 (3 %) patients respectively. Grade 1 pulmonary toxicity presented in 8 patients (4.9 %), and grade 2 in one patient (0.6 %). The most predominant late toxicity was grade 2 hypothyroidism in 37 patients (23 %). Three patients (1.8 %) underwent coronary interventions during follow-up, and one patient was diagnosed with hepatocellular carcinoma 3 months post-RT. No unexpected acute or late toxicities were observed. Proton beam therapy using pencil beam scanning is a safe and effective technique in terms of toxicity and local control, even when irradiating mediastinal targets.

Overview

  • The study aimed to evaluate the toxicity and outcomes of a prospectively observed cohort of patients with mediastinal Hodgkin lymphoma treated with proton beam therapy using pencil beam scanning.
  • A total of 162 patients were irradiated between May 2013 and December 2020, with a median age of 32 years and followed up until April 2024.
  • The primary objective of the study was to assess the safety and efficacy of proton beam therapy in treating mediastinal Hodgkin lymphoma, and specifically to evaluate the toxicity and outcomes of the treatment.

Comparative Analysis & Findings

  • The study found that the disease-free survival, overall survival, and local control rates were 95.1%, 98.8%, and 98.8%, respectively.
  • The most common acute toxicities observed were oesophageal and skin toxicity, with grade 1 oesophageal mucositis occurring in 47% of patients and grade 2 occurring in 10%.
  • The most predominant late toxicity was grade 2 hypothyroidism in 23% of patients, and no unexpected acute or late toxicities were observed.

Implications and Future Directions

  • The study suggests that proton beam therapy using pencil beam scanning is a safe and effective technique in terms of toxicity and local control, even when irradiating mediastinal targets.
  • Future studies could explore the use of proton beam therapy in treating other types of mediastinal tumors, and also investigate ways to further reduce toxicity and improve outcomes.
  • The limitations of the study, such as the relatively small sample size and median follow-up time, should be addressed in future research to further confirm the findings of the study.
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