ESTRO 2024 - Abstract Book

S1135

Clinical - Haematology

ESTRO 2024

Daily KV and cone beam CT (CBCT) imaging were performed. Overall patient setup was consistent. For one pelvic tumour, despite employing a bladder protocol, persistent variation in bladder filling seen between planning CT and MRI scans had the potential to significantly impact dosimetry due to change in density within the beam path. To mitigate this, each repeat planning scan and subsequent treatment delivery was performed with an empty bladder. Dosimetric reviews were required in 4/20 (20%) due to separation gain (n=2; weight gain, deeper inspiration) or separation loss (n=2; due to tumour shrinkage). Only one replan was required, due to a reactive pericardial effusion, causing CTV under dosage.

Weekly treatment reviews assessed toxicity, weight and bloods. Patients were also supported by PBT keyworkers and a team of allied health professionals.

Treatment was manageable with no toxicity RTOG >2. The most common toxicities were fatigue, skin changes, dysphagia and oesophagitis. 12/20 (60%) experienced grade 1 fatigue and 1 patient had grade 2. By 6 weeks these early toxicities had settled in all but 2 patients who had ongoing grade 1 fatigue (n=2) and dysphagia (n=1).

Conclusion:

Our initial experience has demonstrated that PBT delivery in TYA patients is feasible and well tolerated within this limited group of patients. It is anticipated that a wider number and range of disease sites will be treated once routine national commissioning is open. Future plans include the introduction of gating for motion management and ongoing prospective data collection via the proton clinical outcome unit to ascertain which patients would benefit most from this technique.

Keywords: Lymphoma, Proton

References:

Wirth A, Mikjaeel NG et al. Involved Site Radiation Therapy in Adult Lymphomas: An overview of International Lymphoma Radiation Oncology Group Guidelines. International Journal of Radiation Oncology, Biology and Physics 2020; Aug 1;107(5):909-933