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Li MP, Yeo A, Gunewardena R, Drum G, Wiltshire K, Phillips C, Sia J, Wheeler G, Hall L. Is proton beam therapy always better than photon irradiation? Lessons from two cases. J Med Radiat Sci 2024; 71 Suppl 2:90-98. [PMID: 38504608 PMCID: PMC11011607 DOI: 10.1002/jmrs.773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Accepted: 02/07/2024] [Indexed: 03/21/2024] Open
Abstract
Proton beam therapy (PBT) is increasingly used to treat cancers, especially in the paediatric and adolescent and young adult (AYA) population. As PBT becomes more accessible, determining when PBT should be used instead of photon irradiation can be difficult. There is a need to balance patient, tumour and treatment factors when making this decision. Comparing the dosimetry between these two modalities plays an important role in this process. PBT can reduce low to intermediate doses to organs at risk (OAR), but photon irradiation has its dosimetric advantages. We present two cases with brain tumours, one paediatric and one AYA, in which treatment plan comparison between photons and protons showed dosimetric advantages of photon irradiation. The first case was an 18-month-old child diagnosed with posterior fossa ependymoma requiring adjuvant radiotherapy. Photon irradiation using volumetric modulated arc therapy (VMAT) had lower doses to the hippocampi but higher doses to the pituitary gland. The second case was a 21-year-old with an optic pathway glioma. There was better sparing of the critical optic structures and pituitary gland using fractionated stereotactic radiation therapy over PBT. The dosimetric advantages of photon irradiation over PBT have been demonstrated in these cases. This highlights the role of proton-to-photon comparative treatment planning to better understand which patients might benefit from photon irradiation versus PBT.
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Affiliation(s)
- Michelle P Li
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Adam Yeo
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyUniversity of MelbourneMelbourneVictoriaAustralia
- School of Applied ScienceRMIT UniversityMelbourneVictoriaAustralia
| | | | | | - Kirsty Wiltshire
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Claire Phillips
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Joseph Sia
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Greg Wheeler
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
- Sir Peter MacCallum Department of OncologyUniversity of MelbourneMelbourneVictoriaAustralia
| | - Lisa Hall
- Peter MacCallum Cancer CentreMelbourneVictoriaAustralia
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Yang F, Dinakaran D, Heikal AA, Yaghoobpour Tari S, Ghosh S, Amanie J, Murtha A, Rowe LS, Roa WH, Patel S. Dosimetric predictors of toxicity in a randomized study of short-course vs conventional radiotherapy for glioblastoma. Radiother Oncol 2022; 177:152-157. [PMID: 36273738 DOI: 10.1016/j.radonc.2022.10.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 09/12/2022] [Accepted: 10/14/2022] [Indexed: 11/13/2022]
Abstract
PURPOSE There is no consensus on appropriate organ at risk (OAR) constraints for short-course radiotherapy for patients with glioblastoma. Using dosimetry and prospectively-collected toxicity data from a trial of short-course radiotherapy for glioblastoma, this study aims to empirically examine the OAR constraints, with particular attention to left hippocampus dosimetry and impact on neuro-cognitive decline. METHODS AND MATERIALS Data was taken from a randomized control trial of 133 adults (age 18-70 years; ECOG performance score 0-2) with newly diagnosed glioblastoma treated with 60 Gy in 30 (conventional arm) versus 20 (short-course arm) fractions of adjuvant chemoradiotherapy (ClinicalTrials.gov Identifier: NCT02206230). The delivered plan's dosimetry to the OARs was correlated to prospective-collected toxicity and Mini-Mental State Examination (MMSE) data. RESULTS Toxicity events were not significantly increased in the short-course arm versus the conventional arm. Across all OARs, delivered radiation doses within protocol-allowable maximum doses correlated with lack of grade ≥ 2 toxicities in both arms (p < 0.001), while patients with OAR doses at or above protocol limits correlated with increased grade ≥ 2 toxicities across all examined OARs in both arms (p-values 0.063-0.250). Mean left hippocampus dose was significantly associated with post-radiotherapy decline in MMSE scores (p = 0.005), while the right hippocampus mean dose did not reach statistical significance (p = 0.277). Compared to the original clinical plan, RapidPlan left hippocampus sparing model decreased left hippocampus mean dose by 43 % (p < 0.001), without compromising planning target volume coverage. CONCLUSIONS In this trial, protocol OAR constraints were appropriate for limiting grade ≥ 2 toxicities in conventional and short-course adjuvant chemoradiotherapy for glioblastoma. Higher left hippocampal mean doses were predictive for neuro-cognitive decline post-radiotherapy. Routine contouring and use of dose constraints to limit hippocampal dose is recommended to minimize neuro-cognitive decline in patients with glioblastoma treated with chemoradiotherapy.
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Affiliation(s)
- Fan Yang
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Deepak Dinakaran
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Amr A Heikal
- Division of Medical Physics, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Shima Yaghoobpour Tari
- Division of Medical Physics, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Sunita Ghosh
- Division of Medical Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - John Amanie
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Albert Murtha
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Lindsay S Rowe
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Wilson H Roa
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Samir Patel
- Division of Radiation Oncology, University of Alberta, Cross Cancer Institute, Edmonton, Alberta, Canada.
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