Copenhagen, Denmark
Onsite/Online

ESTRO 2022

Session Item

Monday
May 09
14:15 - 15:15
Mini-Oral Theatre 2
22: AI, big data, automation
Eugenia Vlaskou Badra, Switzerland;
Stephanie Tanadini-Lang, Switzerland
Mini-Oral
Interdisciplinary
Proton Beam Therapy for Central Nervous System tumours: outcomes from the Proton Overseas Programme
Simona Gaito, United Kingdom
MO-0883

Abstract

Proton Beam Therapy for Central Nervous System tumours: outcomes from the Proton Overseas Programme
Authors:

Simona Gaito1,2, Eunji Hwang3,4, Anna France1, Gillian Whitfield3,2, Shermaine Pan5, Gareth Price2, Marianne Aznar2, Adrian Crellin6, Daniel Indelicato7, Ed Smith3,1,2

1The Christie NHS Foundation Trust, Proton Clinical Outcomes Unit, Manchester, United Kingdom; 2University of Manchester, Manchester Cancer Research Centre, Manchester, United Kingdom; 3The Christie NHS Foundation Trust, The Christie Proton Beam Therapy Centre, Manchester, United Kingdom; 4Institute of Medical Physics, School of Physics, University of Sidney, Australia; 5The Christie NHS Foundation Trust, The Christie Proton Beam Therapy centre, Manchester, United Kingdom; 6NHS England, National Clinical Lead Proton Beam Therapy, Manchester, United Kingdom; 7University of Florida, Department of Radiation Oncology, Jacksonville, USA

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Purpose or Objective

In 2008, the UK National Health Service (NHS) started the Proton Overseas Programme (POP), to provide access for Proton Beam Therapy (PBT) abroad for selected tumour diagnoses, whilst two national centres were being planned. This work reports the moderate-severe toxicities and their incidence in the patient group treated for Central Nervous System (CNS) malignancies.

Material and Methods

Since the start of the NHS POP Programme, an agreement between NHS England and UK referring centres ensured outcomes data collection. Follow-up correspondence has been stored in patient files in a national database and curated by the Proton Clinical Outcomes Unit, established in 2018.

Clinical and treatment-related data were extracted from the central patient database. The POP patient cohort was divided into CNS and extracranial diseases. Spinal and skull base (BoS) chordoma and chondrosarcoma were grouped with CNS diseases. Grade (G) ≥3 late toxicities (LT), as per CTCAE (Common Terminology Criteria for Adverse Events) v 4.0 definition, occurring later than 90 days since completion of treatment, were recorded.  Where toxicity could not be graded accurately, individualised workbooks were sent to referring centres for clarification. The follow up time is calculated from end of PBT treatment to death or last follow up.

Results

Between 2008 and September 2020, 830 patients were treated within the POP for CNS malignancies. Their demographics and clinical characteristics are listed in Table 1. After a median follow up of 2.65 years (range 0.03 - 11.59) the overall survival for the whole cohort was 91.33%, and the local control was 75.42%. Of note, the local control was unknown in 12.29% of the patients, and 12.29% experienced disease progression. Toxicity analysis (Table 2) was carried out on 760 patients, with patients excluded due to short follow-up (<90 days) and/or inadequate toxicity data available. Median follow up in this population is 2.8 years (0.26 - 11.59), and median radiotherapy prescription dose 54 GyRBE (34.8-79.2).


In total, 69 patients (9.1%) experienced G≥3 LT, with 18 (2.4%) experiencing more than one toxicity. Of note, G≥3 LT are more common in those tumour groups (such as Chordomas and Chondrosarcomas) receiving dose-escalated treatments, and in those (such as Craniopharyngiomas and Ependymoma) commonly located in close proximity to critical organs at risk and background of multiple surgical procedures. 

Conclusion

The results of this study indicate safety of PBT for CNS tumours, with predominantly passive scattering. Clinical outcomes from this cohort will be compared with the newest Pencil Beam Scanning technology, in the UK NHS National PBT service. Baseline toxicity assessment is essential for the correct interpretation of radiotherapy toxicities and longer follow up is needed to evaluate endpoints, such as secondary malignancies, which have a long latency period.