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Gaudreault M, Yu KK, Chang D, Kron T, Hardcastle N, Chander S, Yeo A. Automated lattice radiation therapy treatment planning personalised to tumour size and shape. Phys Med 2024; 125:104490. [PMID: 39142028 DOI: 10.1016/j.ejmp.2024.104490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 07/09/2024] [Accepted: 07/22/2024] [Indexed: 08/16/2024] Open
Abstract
PURPOSE Lattice radiation therapy (LRT) alternates regions of high and low doses inside the tumour. Whilst this technique reported positive results in tumour size reduction, optimal lattice parameters are still unknown. We introduce an automated LRT planning method personalised to tumour shape and designed to allow investigation of lattice geometry. METHODS Patients with retroperitoneal sarcoma were considered for inclusion. Automation was performed with the Eclipse Scripting Application Interface (v16, Varian Medical Systems, Palo Alto). By iterating over vertex size (V) and centre-to-centre distance (D), vertices were segmented within the gross tumour volume (GTV) in an alternating square pattern. Iterations stopped when the number of inserted vertices was contained between a prespecified lower and upper bound. Forty sets of lattices were considered, produced by varying V and D in five lower/upper bound pairs. Best-scoring sets were determined with a score favouring the maximization of GTV dose uniformity and heterogeneity whilst minimizing the maximum dose to organs at risk. RESULTS Fifty patients with tumour volumes between 150 cm3 and 10,000 cm3 were included. Best-scoring sets were characterised by a low number of vertices (<15). Based on the best-scoring set, the predicted parameters to use for new patients were V = 0.19 (GTV volume)1/3 and D = 2V, in centimetres. The number of vertices (N) to insert in the GTV can be estimated with N ≤ (24 × 3% GTV volume)/(4πV3). CONCLUSIONS The automated LRT treatment planning personalised to tumour size allows investigation of lattice geometry over a large range of GTV volumes.
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Affiliation(s)
- Mathieu Gaudreault
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum, Department of Oncology, the University of Melbourne, Victoria 3000, Australia.
| | - Kelvin K Yu
- Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Benavides Cancer Institute - University of Santo Tomas Hospital, Manila, Philippines
| | - David Chang
- Sir Peter MacCallum, Department of Oncology, the University of Melbourne, Victoria 3000, Australia; Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Tomas Kron
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum, Department of Oncology, the University of Melbourne, Victoria 3000, Australia; Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia
| | - Nicholas Hardcastle
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum, Department of Oncology, the University of Melbourne, Victoria 3000, Australia; Centre for Medical Radiation Physics, University of Wollongong, NSW 2522, Australia
| | - Sarat Chander
- Sir Peter MacCallum, Department of Oncology, the University of Melbourne, Victoria 3000, Australia; Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia
| | - Adam Yeo
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum, Department of Oncology, the University of Melbourne, Victoria 3000, Australia
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Kunkyab T, Magliari A, Jirasek A, Mou B, Hyde D. Semi-automated vertex placement for lattice radiotherapy and dosimetric verification using 3D polymer gel dosimetry. J Appl Clin Med Phys 2024:e14489. [PMID: 39186819 DOI: 10.1002/acm2.14489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/03/2024] [Accepted: 06/28/2024] [Indexed: 08/28/2024] Open
Abstract
PURPOSE To evaluate the feasibility of an open-source, semi-automated, and reproducible vertex placement tool to improve the efficiency of lattice radiotherapy (LRT) planning. We used polymer gel dosimetry with a Cone Beam CT (CBCT) readout to commission this LRT technique. MATERIAL AND METHODS We generated a volumetric modulated arc therapy (VMAT)-based LRT plan on a 2 L NIPAM polymer gel dosimeter using our Eclipse Acuros version 15.6 AcurosXB beam model, and also recalculated the plan with a pre-clinical Acuros v18.0 dose calculation algorithm with the enhanced leaf modelling (ELM). With the assistance of the MAAS-SFRThelper software, a lattice vertex diameter of 1.5 cm and center-to-center spacing of 3 cm were used to place the spheres in a hexagonal, closed packed structure. The verification plan included four gantry arcs with 15°, 345°, 75°, 105° collimator angles. The spheres were prescribed 20 Gy to 50% of their combined volume. The 6 MV Flattening Filter Free beam energy was used to deliver the verification plan. The dosimetric accuracy of the LRT delivery was evaluated with 1D dose profiles, 2D isodose maps, and a 3D global gamma analysis. RESULTS Qualitative comparisons between the 1D dose profiles of the Eclipse plan and measured gel showed good consistency at the prescription dose mark. The average diameter measured 13.3 ± 0.2 mm (gel for v15.6), 12.6 mm (v15.6 plan), 13.1 ± 0.2 mm (gel for v18.0), and 12.3 mm (v18.0 plan). 3D gamma analysis showed that all gamma pass percent were > 95% except at 1% and 2% at the 1 mm distance to agreement criteria. CONCLUSION This study presents a novel application of gel dosimetry in verifying the dosimetric accuracy of LRT, achieving excellent 3D gamma results. The treatment planning was facilitated by publicly available software that automatically placed the vertices for consistency and efficiency.
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Affiliation(s)
- Tenzin Kunkyab
- Department of Computer Science, Mathematics, Physics and Statistics, The University of British Columbia Okanagan, Kelowna, British Columbia, Canada
- BC Cancer, Kelowna, British Columbia, Canada
| | | | - Andrew Jirasek
- Department of Computer Science, Mathematics, Physics and Statistics, The University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Benjamin Mou
- BC Cancer, Kelowna, British Columbia, Canada
- Department of Surgery, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Derek Hyde
- Department of Computer Science, Mathematics, Physics and Statistics, The University of British Columbia Okanagan, Kelowna, British Columbia, Canada
- BC Cancer, Kelowna, British Columbia, Canada
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McMillan MT, Khan AJ, Powell SN, Humm J, Deasy JO, Haimovitz-Friedman A. Spatially Fractionated Radiotherapy in the Era of Immunotherapy. Semin Radiat Oncol 2024; 34:276-283. [PMID: 38880536 DOI: 10.1016/j.semradonc.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Spatially fractionated radiotherapy (SFRT) includes historical grid therapy approaches but more recently encompasses the controlled introduction of one or more cold dose regions using intensity modulation delivery techniques. The driving hypothesis behind SFRT is that it may allow for an increased immune response that is otherwise suppressed by radiation effects. With both two- and three-dimensional SFRT approaches, SFRT dose distributions typically include multiple dose cold spots or valleys. Despite its unconventional methods, reported clinical experience shows that SFRT can sometimes induce marked tumor regressions, even in patients with large hypoxic tumors. Preclinical models using extreme dose distributions (i.e., half-sparing) have been shown to nevertheless result in full tumor eradications, a more robust immune response, and systemic anti-tumor immunity. SFRT takes advantage of the complementary immunomodulatory features of low- and high-dose radiotherapy to integrate the delivery of both into a single target. Clinical trials using three-dimensional SFRT (i.e., lattice-like dose distributions) have reported both promising tumor and toxicity results, and ongoing clinical trials are investigating synergy between SFRT and immunotherapies.
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Affiliation(s)
| | | | | | - John Humm
- Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY
| | - Joseph O Deasy
- Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY
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Grahvendy M, Brown B, Wishart LR. Adverse Event Reporting in Cancer Clinical Trials: Incorporating Patient-Reported Methods. A Systematic Scoping Review. THE PATIENT 2024; 17:335-347. [PMID: 38589749 PMCID: PMC11189958 DOI: 10.1007/s40271-024-00689-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/10/2024] [Indexed: 04/10/2024]
Abstract
BACKGROUND AND OBJECTIVE The history of clinical trials is fraught with unethical practices. Since 1945, robust frameworks have evolved to standardise the collection and reporting of safety data, most notably, the Common Terminology Criteria for Adverse Events (CTCAE) from the National Cancer Institute; used by investigators to report side effects experienced by participants. As medicine moves into the patient-centred model, interest has been growing to collect data on adverse events directly from participants (patient-reported adverse events). The aim of this systematic scoping review was to investigate the inclusion of patient-reported adverse event data within safety/tolerability analyses and explore the collection and reporting of patient-reported adverse event data. METHODS AND RESULTS A database search was undertaken and the Covidence platform was used to manage the review; results were analysed descriptively. Sixty-eight studies were included in the analysis. An increase in the number of studies that incorporate patient-reported adverse event data was seen by year. Seventy instruments were used for the collection of patient-reported adverse event data with recall period, mode, frequency and site of administration varying across studies; the duration of data collection ranged from 28 days to 6 years. Frequently, information on these details was omitted from publications. The number of instruments used by studies to collect patient-reported adverse event data ranged from one to seven instruments. CONCLUSIONS Despite growing calls for the inclusion of patient-reported adverse events, this has not yet translated into published reports. The collection and reporting of these data were variable and conducted using instruments that were not designed for purpose. To address these inconsistencies, standardisation of data collection and reporting using a purpose-built validated instrument is required.
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Affiliation(s)
- Minna Grahvendy
- Cancer Trials Unit, Princess Alexandra Hospital, Queensland Health, Brisbane, QLD, 4102, Australia.
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, QLD, Australia.
| | - Bena Brown
- Southern Queensland Centre of Excellence in Aboriginal and Torres Strait, Islander Primary Health Care, Metro South Health, Brisbane, QLD, Australia
- School of Public Health, The University of Queensland, Brisbane, QLD, Australia
| | - Laurelie R Wishart
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, QLD, Australia
- Centre for Functioning and Health Research, Metro South Health, Brisbane, QLD, Australia
- Centre for Applied Health Economics, School of Medicine and Dentistry, Griffith University, Brisbane, QLD, Australia
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Ginn J, Duriseti S, Mazur T, Spraker M, Kavanaugh J. A Dose Accumulation Assessment of Alignment Errors During Spatially Fractionated Radiation Therapy. Pract Radiat Oncol 2024; 14:e283-e290. [PMID: 38081359 DOI: 10.1016/j.prro.2023.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 01/27/2024]
Abstract
PURPOSE Spatially fractionated radiation therapy (SFRT) techniques produce high-dose peaks and low-dose valleys within a tumor. Lattice stereotactic body radiation therapy (SBRT) is a form a SFRT delivered across 5 fractions. Because of the high spatial dose gradients associated with SFRT, it is critical for fractionated SFRT patients to be aligned correctly for treatment. Here we investigate the dosimetric effect of daily alignment uncertainty through a dose accumulation study. METHODS AND MATERIALS Dose accumulation was retrospectively performed for 10 patients enrolled on a phase 1 trial. Lattice stereotactic body radiation therapy was completed in 5 fractions with 20 Gy prescribed to the entire tumor and a simultaneous integrated boost of 66.7 Gy prescribed to a set of regularly spaced high-dose spheres. Daily alignment error was quantified through manually selected landmarks in both the planning computed tomography scan and daily cone beam computed tomography. The dosimetric effect of alignment errors was quantified by translating the isocenter in the treatment planning system by the daily average alignment error. Large errors were simulated by translating isocenter 5 and 10 mm for 1 and 2 fractions, independently assessing errors in the superior-inferior and axial directions. The reduction of dose gradients was quantified using the dose ratio (DR) of the mean dose in the high-dose and low-dose spheres. RESULTS The average alignment error was 1.8 mm across the patient population resulting in minor smoothing of the high- and low-dose distributions in the dose accumulation. Quantitatively, the DR decreased from 3.42 to 3.32 (P = .093) in the dose accumulation study. The simulated worst case was an inferior-superior shift of 10 mm for 2 fractions where the average DR decreased to 2.72 (P = .0001). CONCLUSIONS The dose accumulation study revealed on average DR only decreased from 3.42 to 3.32. However, setup errors >5 mm resulted in larger dosimetric degradation, reflecting a larger effect for individual high-dose spheres within regions exhibiting larger displacements.
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Affiliation(s)
- John Ginn
- Department of Radiation Oncology, Duke University, Durham, North Carolina
| | - Sai Duriseti
- Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California
| | - Thomas Mazur
- Department of Radiation Oncology, Washington University in St Louis, St. Louis, Missouri
| | | | - James Kavanaugh
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
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Jenkins SV, Johnsrud AJ, Dings RPM, Griffin RJ. Bystander Effects in Spatially Fractionated Radiation Therapy: From Molecule To Organism To Clinical Implications. Semin Radiat Oncol 2024; 34:284-291. [PMID: 38880537 PMCID: PMC11185274 DOI: 10.1016/j.semradonc.2024.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
The standard of care for radiation therapy is numerous, low-dose fractions that are distributed homogeneously throughout the tumor. An alternative strategy under scrutiny is to apply spatially fractionated radiotherapy (high and low doses throughout the tumor) in one or several fractions, either alone or followed by conventional radiation fractionation . Spatial fractionation allows for significant sparing of normal tissue, and the regions of tumor or normal tissue that received sublethal doses can give rise to beneficial bystander effects in both cases. Bystander effects are broadly defined as biological responses that are significantly greater than would be anticipated based on the radiation dose received. Typically these effects are initiated by diffusion of reactive oxygen species and secretion of various cytokines. As demonstrated in the literature, spatial fractionation related bystander effects can occur locally from cell to cell and in what are known as "cohort effects," which tend to take the form of restructuring of the vasculature, enhanced immune infiltration, and development of immunological memory. Other bystander effects can take place at distant sites in what are known as "abscopal effects." While these events are rare, they are mediated by the immune system and can result in the eradication of secondary and metastatic disease. Currently, due to the complexity and variability of these bystander effects, they are not thoroughly understood, but as knowledge improves they may present significant opportunities for improved clinical outcomes.
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Affiliation(s)
- Samir V Jenkins
- Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR..
| | | | - Ruud P M Dings
- Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR
| | - Robert J Griffin
- Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR
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Mossahebi S, Molitoris JK, Poirier Y, Jatczak J, Zhang B, Mohindra P, Ferris M, Regine WF, Yi B. Clinical Implementation and Dosimetric Evaluation of a Robust Proton Lattice Planning Strategy Using Primary and Robust Complementary Beams. Int J Radiat Oncol Biol Phys 2024:S0360-3016(24)00742-9. [PMID: 38936634 DOI: 10.1016/j.ijrobp.2024.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 05/17/2024] [Accepted: 06/15/2024] [Indexed: 06/29/2024]
Abstract
PURPOSE Pencil-beam scanning proton therapy has been considered a potential modality for the 3D form of spatially fractionated radiation therapy called lattice therapy. However, few practical solutions have been introduced in the clinic. Existing limitations include degradation in plan quality and robustness when using single-field versus multifield lattice plans, respectively. We propose a practical and robust proton lattice (RPL) planning method using multifield and evaluate its dosimetric characteristics compared to clinically acceptable photon lattice plans. METHODS AND MATERIALS Seven cases previously treated with photon lattice therapy were used to evaluate a novel RPL planning technique using 2-orthogonal beams: a primary beam (PB) and a robust complementary beam (RCB) that deliver 67% and 33%, respectively, of the prescribed dose to vertices inside the gross target volume (GTV). Only RCB is robustly optimized for setup and range uncertainties. The number and volume of vertices, peak-to-valley dose ratios (PVDRs), and volume of low dose to GTV of proton and photon plans were compared. The RPL technique was then used in the treatment of 2 patients and their dosimetric parameters were reported. RESULTS The RPL strategy was able to achieve the clinical planning goals. Compared to previously treated photon plans, the average number of vertices increased by 30%, the average vertex volume by 49% (18.2 ± 25.9 cc vs 12.2 ± 14.5 cc, P = .21), and higher PVDR (10.5 ± 4.8 vs 2.5 ± 0.9, P < .005) was achieved. In addition, RPL plans show more conformal dose with less low dose to GTV (V30%, 60.9% ± 7.2% vs 81.6% ± 13.9% and V10%, 88.3% ± 4.5% vs 98.6% ± 3.6% [P < .01]). The RPL plan for 2 treated patients showed PVDRs of 4.61 and 14.85 with vertices-to-GTV ratios of 1.52% and 1.30%, respectively. CONCLUSIONS A novel RPL planning strategy using a pair of orthogonal beams was developed and successfully translated to the clinic. The proposed method can generate better quality plans, a higher number of vertices, and higher PVDRs than currently used photon lattice plans.
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Affiliation(s)
- Sina Mossahebi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland; Maryland Proton Treatment Center, Baltimore, Maryland.
| | - Jason K Molitoris
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland; Maryland Proton Treatment Center, Baltimore, Maryland
| | - Yannick Poirier
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jenna Jatczak
- Maryland Proton Treatment Center, Baltimore, Maryland
| | - Baoshe Zhang
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland; Maryland Proton Treatment Center, Baltimore, Maryland
| | - Pranshu Mohindra
- Department of Radiation Oncology, University Hospitals Cleveland Medical Center, Cleveland, Ohio
| | - Matthew Ferris
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland; Maryland Proton Treatment Center, Baltimore, Maryland
| | - William F Regine
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland; Maryland Proton Treatment Center, Baltimore, Maryland
| | - ByongYong Yi
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, Maryland; Maryland Proton Treatment Center, Baltimore, Maryland
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Prezado Y, Grams M, Jouglar E, Martínez-Rovira I, Ortiz R, Seco J, Chang S. Spatially fractionated radiation therapy: a critical review on current status of clinical and preclinical studies and knowledge gaps. Phys Med Biol 2024; 69:10TR02. [PMID: 38648789 DOI: 10.1088/1361-6560/ad4192] [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: 11/27/2023] [Accepted: 04/22/2024] [Indexed: 04/25/2024]
Abstract
Spatially fractionated radiation therapy (SFRT) is a therapeutic approach with the potential to disrupt the classical paradigms of conventional radiation therapy. The high spatial dose modulation in SFRT activates distinct radiobiological mechanisms which lead to a remarkable increase in normal tissue tolerances. Several decades of clinical use and numerous preclinical experiments suggest that SFRT has the potential to increase the therapeutic index, especially in bulky and radioresistant tumors. To unleash the full potential of SFRT a deeper understanding of the underlying biology and its relationship with the complex dosimetry of SFRT is needed. This review provides a critical analysis of the field, discussing not only the main clinical and preclinical findings but also analyzing the main knowledge gaps in a holistic way.
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Affiliation(s)
- Yolanda Prezado
- Institut Curie, Université PSL, CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, F-91400, Orsay, France
- Université Paris-Saclay, CNRS UMR3347, Inserm U1021, Signalisation Radiobiologie et Cancer, F-91400, Orsay, France
- New Approaches in Radiotherapy Lab, Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), Instituto de investigación Sanitaria de Santiago de Compostela (IDIS), University of Santiago de Compostela, Santiago de Compostela, A Coruña, E-15706, Spain
- Oportunius Program, Galician Agency of Innovation (GAIN), Xunta de Galicia, Santiago de Compostela, A Coruña, Spain
| | - Michael Grams
- Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, United States of America
| | - Emmanuel Jouglar
- Institut Curie, PSL Research University, Department of Radiation Oncology, F-75005, Paris and Orsay Protontherapy Center, F-91400, Orsay, France
| | - Immaculada Martínez-Rovira
- Physics Department, Universitat Auto`noma de Barcelona, E-08193, Cerdanyola del Valle`s (Barcelona), Spain
| | - Ramon Ortiz
- University of California San Francisco, Department of Radiation Oncology, 1600 Divisadero Street, San Francisco, CA 94143, United States of America
| | - Joao Seco
- Division of Biomedical physics in Radiation Oncology, DKFZ-German Cancer Research Center, Heidelberg, Germany
- Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany
| | - Sha Chang
- Dept of Radiation Oncology and Department of Biomedical Engineering, University of North Carolina School of Medicine, United States of America
- Department of Clinical Sciences, College of Veterinary Medicine, North Carolin State University, United States of America
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Gaudreault M, Chang D, Kron T, Siva S, Chander S, Hardcastle N, Yeo A. Development of an automated treatment planning approach for lattice radiation therapy. Med Phys 2024; 51:682-693. [PMID: 37797078 DOI: 10.1002/mp.16761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 08/29/2023] [Accepted: 09/14/2023] [Indexed: 10/07/2023] Open
Abstract
BACKGROUND Lattice radiation therapy (LRT) alternates regions of high and low doses within the target. The heterogeneous dose distribution is delivered to a geometrical structure of vertices segmented inside the tumor. LRT is typically used to treat patients with large tumor volumes with cytoreduction intent. Due to the geometric complexity of the target volume and the required dose distribution, LRT treatment planning demands additional resources, which may limit clinical integration. PURPOSE We introduce a fully automated method to (1) generate an ordered lattice of vertices with various sizes and center-to-center distances and (2) perform dose optimization and calculation. We aim to report the dosimetry associated with these lattices to help clinical decision-making. METHODS Sarcoma cancer patients with tumor volume between 100 cm3 and 1500 cm3 who received radiotherapy treatment between 2010 and 2018 at our institution were considered for inclusion. Automated segmentation and dose optimization/calculation were performed by using the Eclipse Scripting Application Programming Interface (ESAPI, v16, Varian Medical Systems, Palo Alto, USA). Vertices were modeled by spheres segmented within the gross tumor volume (GTV) with 1 cm/1.5 cm/2 cm diameters (LRT-1 cm/1.5 cm/2 cm) and 2 to 5 cm center-to-center distance on square lattices alternating along the superior-inferior direction. Organs at risk were modeled by subtracting the GTV from the body structure (body-GTV). The prescription dose was that 50% of the vertice volume should receive at least 20 Gy in one fraction. The automated dose optimization included three stages. The vertices optimization objectives were refined during optimization according to their values at the end of the first and second stages. Lattices were classified according to a score based on the minimization of body-GTV max dose and the maximization of GTV dose uniformity (measured with the equivalent uniform dose [EUD]), GTV dose heterogeneity (measured with the GTV D90%/D10% ratio), and the number of patients with more than one vertex inserted in the GTV. Plan complexity was measured with the modulation complexity score (MCS). Correlations were assessed with the Spearman correlation coefficient (r) and its associated p-value. RESULTS Thirty-three patients with GTV volumes between 150 and 1350 cm3 (median GTV volume = 494 cm3 , IQR = 272-779 cm3 were included. The median time required for segmentation/planning was 1 min/21 min. The number of vertices was strongly correlated with GTV volume in each LRT lattice for each center-to-center distance (r > 0.85, p-values < 0.001 in each case). Lattices with center-to-center distance = 2.5 cm/3 cm/3.5 cm in LRT-1.5 cm and center-to-center distance = 4 cm in LRT-1 cm had the best scores. These lattices were characterized by high heterogeneity (median GTV D90%/D10% between 0.06 and 0.19). The generated plans were moderately complex (median MCS ranged between 0.19 and 0.40). CONCLUSIONS The automated LRT planning method allows for the efficacious generation of vertices arranged in an ordered lattice and the refinement of planning objectives during dose optimization, enabling the systematic evaluation of LRT dosimetry from various lattice geometries.
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Affiliation(s)
- Mathieu Gaudreault
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
| | - David Chang
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Tomas Kron
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Sydney, New South Wales, Australia
| | - Shankar Siva
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Sarat Chander
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- Division of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Nicholas Hardcastle
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Sydney, New South Wales, Australia
| | - Adam Yeo
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Victoria, Australia
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10
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Tucker WW, Mazur TR, Schmidt MC, Hilliard J, Badiyan S, Spraker MB, Kavanaugh JA. Script-based implementation of automatic grid placement for lattice stereotactic body radiation therapy. Phys Imaging Radiat Oncol 2024; 29:100549. [PMID: 38380154 PMCID: PMC10876586 DOI: 10.1016/j.phro.2024.100549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/26/2024] [Accepted: 02/05/2024] [Indexed: 02/22/2024] Open
Abstract
Background and purpose Spatially fractionated radiation therapy (SFRT) has demonstrated promising clinical response in treating large tumors with heterogeneous dose distributions. Lattice stereotactic body radiation therapy (SBRT) is an SFRT technique that leverages inverse optimization to precisely localize regions of high and lose dose within disease. The aim of this study was to evaluate an automated heuristic approach to sphere placement in lattice SBRT treatment planning. Materials and methods A script-based algorithm for sphere placement in lattice SBRT based on rules described by protocol was implemented within a treatment planning system. The script was applied to 22 treated cases and sphere distributions were compared with manually placed spheres in terms of number of spheres, number of protocol violations, and time required to place spheres. All cases were re-planned using script-generated spheres and plan quality was compared with clinical plans. Results The mean number of spheres placed excluding those that violate rules was greater using the script (13.8) than that obtained by either dosimetrist (10.8 and 12.0, p < 0.001 and p = 0.003) or physicist (12.7, p = 0.061). The mean time required to generate spheres was significantly less using the script (2.5 min) compared to manual placement by dosimetrists (25.0 and 29.9 min) and physicist (19.3 min). Plan quality indices were similar in all cases with no significant differences, and OAR constraints remained met on all plans except two. Conclusion A script placed spheres for lattice SBRT according to institutional protocol rules. The script-produced placement was superior to that of manually-specified spheres, as characterized by sphere number and rule violations.
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Affiliation(s)
- Wesley W. Tucker
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Thomas R. Mazur
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Matthew C. Schmidt
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Jessica Hilliard
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
| | - Shahed Badiyan
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO 63110 USA
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11
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Lukas L, Zhang H, Cheng K, Epstein A. Immune Priming with Spatially Fractionated Radiation Therapy. Curr Oncol Rep 2023; 25:1483-1496. [PMID: 37979032 PMCID: PMC10728252 DOI: 10.1007/s11912-023-01473-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE OF REVIEW This review aims to summarize the current preclinical and clinical evidence of nontargeted immune effects of spatially fractionated radiation therapy (SFRT). We then highlight strategies to augment the immunomodulatory potential of SFRT in combination with immunotherapy (IT). RECENT FINDINGS The response of cancer to IT is limited by primary and acquired immune resistance, and strategies are needed to prime the immune system to increase the efficacy of IT. Radiation therapy can induce immunologic effects and can potentially be used to synergize the effects of IT, although the optimal combination of radiation and IT is largely unknown. SFRT is a novel radiation technique that limits ablative doses to tumor subvolumes, and this highly heterogeneous dose deposition may increase the immune-rich infiltrate within the targeted tumor with enhanced antigen presentation and activated T cells in nonirradiated tumors. The understanding of nontargeted effects of SFRT can contribute to future translational strategies to combine SFRT and IT. Integration of SFRT and IT is an innovative approach to address immune resistance to IT with the overall goal of improving the therapeutic ratio of radiation therapy and increasing the efficacy of IT.
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Affiliation(s)
- Lauren Lukas
- Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
| | - Hualin Zhang
- Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Karen Cheng
- Department of Radiation Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Alan Epstein
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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12
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Hatoum GF, Temple HT, Garcia SA, Zheng Y, Kfoury F, Kinley J, Wu X. Neoadjuvant Radiation Therapy with Interdigitated High-Dose LRT for Voluminous High-Grade Soft-Tissue Sarcoma. Cancer Manag Res 2023; 15:113-122. [PMID: 36776730 PMCID: PMC9910204 DOI: 10.2147/cmar.s393934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 01/18/2023] [Indexed: 02/05/2023] Open
Abstract
Purpose To report a case of large extremity soft tissue sarcoma (2933 cc), safely treated with a novel approach of interdigitating high-dose LATTICE radiation therapy (LRT) with standard radiation therapy as a neoadjuvant treatment to surgery. Patients and Methods Four sessions of high-dose LRT were delivered in a weekly interval, interdigitated with standard radiation therapy. The LRT plan consisted of 15 high-dose vertices receiving a dose >12 Gy per session, with 2-3 Gy to the peripheral margin of the tumor. The patient underwent surgical excision 2 months after the new regimen of induction radiation therapy. Results and Discussion The patient tolerated the radiation therapy regimen well. The post-operative assessment revealed a negative surgical margin and over 95% necrosis of the total tumor volume. The post-surgical wound complication was mitigated by outpatient wound care. Interdigitating multiple sessions of high-dose LATTICE radiation treatments with standard neoadjuvant radiation therapy as a neoadjuvant therapy for soft tissue sarcoma was feasible and did not incur additional toxicity in this clinical case. A phase-I/II trial will be conducted to further evaluate the toxicity and efficacy of the new treatment strategy with the intent to increase the rate of pathologic necrosis, which has been shown to positively correlate with the overall survival.
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Affiliation(s)
- Georges F Hatoum
- Department of Radiation Oncology, HCA Florida JFK Medical Center Comprehensive Cancer Institute, Lake Worth, FL, USA
| | - H Thomas Temple
- Department of Orthopedic Surgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Silvio A Garcia
- Department of Radiation Oncology, HCA Florida JFK Medical Center Comprehensive Cancer Institute, Lake Worth, FL, USA
| | - Yi Zheng
- Department of Radiation Oncology, HCA Florida JFK Medical Center Comprehensive Cancer Institute, Lake Worth, FL, USA
- Department of Research and Development, Executive Medical Physics Associates, North Miami Beach, FL, USA
| | - Fouad Kfoury
- Pharmacy Department, South Miami Hospital, South Miami, FL, USA
| | - Jill Kinley
- Department of Clinical Research, HCA Florida JFK Medical Center, Atlantis, FL, USA
| | - Xiaodong Wu
- Department of Radiation Oncology, HCA Florida JFK Medical Center Comprehensive Cancer Institute, Lake Worth, FL, USA
- Department of Research and Development, Executive Medical Physics Associates, North Miami Beach, FL, USA
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13
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Lattice Radiation Therapy in clinical practice: A systematic review. Clin Transl Radiat Oncol 2022; 39:100569. [PMID: 36590825 PMCID: PMC9800252 DOI: 10.1016/j.ctro.2022.100569] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/14/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Purpose Lattice radiation therapy (LRT) is an innovative type of spatially fractionated radiation therapy. It aims to increase large tumors control probability by administering ablative doses without an increased toxicity. Considering the rising number of positive clinical experiences, the objective of this work is to evaluate LRT safety and efficacy. Method Reports about LRT clinical experience were identified with a systematic review conducted on four different databases (namely, Medline, Embase, Scopus, and Cochrane Library) through the August 2022. Only LRT clinical reports published in English and with the access to the full manuscript text were considered as eligible. The 2020 update version PRISMA statement was followed. Results Data extraction was performed from 12 eligible records encompassing 7 case reports, 1 case series, and 4 clinical studies. 81 patients (84 lesions) with a large lesion ranging from 63.2 cc to 3713.5 cc were subjected to exclusive, hybrid, and metabolism guided LRT. Excluding two very severe toxicity with a questionable relation with LRT, available clinical experience seem to confirm LRT safety. When a complete response was not achieved 3-6 months after LRT, a median lesion reduction approximately ≥50 % was registered. Conclusion This systematic review appear to suggest LRT safety, especially for exclusive LRT. The very low level of evidence and the studies heterogeneity preclude drawing definitive conclusions on LRT efficacy, even though an interesting trend in terms of lesions reduction has been described.
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14
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Impressive Results after "Metabolism-Guided" Lattice Irradiation in Patients Submitted to Palliative Radiation Therapy: Preliminary Results of LATTICE_01 Multicenter Study. Cancers (Basel) 2022; 14:cancers14163909. [PMID: 36010902 PMCID: PMC9406022 DOI: 10.3390/cancers14163909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/05/2022] [Accepted: 08/11/2022] [Indexed: 11/17/2022] Open
Abstract
Purpose: To evaluate feasibility, toxicities, and clinical response in Stage IV patients treated with palliative “metabolism-guided” lattice technique. Patients and Methods: From June 2020 to December 2021, 30 consecutive clinical stage IV patients with 31 bulky lesions were included in this study. All patients received palliative irradiation consisting of a spatially fractionated high radiation dose delivered in spherical deposits (vertices, Vs) within the bulky disease. The Vs were placed at the edges of tumor areas with different metabolisms at the PET exam following a non-geometric arrangement. Precisely, the Vs overlapped the interfaces between the tumor areas of higher 18F-FDG uptake (>75% SUV max) and areas with lower 18F-FDG uptake. A median dose of 15 Gy/1 fraction (range 10−27 Gy in 1/3 fractions) was delivered to the Vs. Within 7 days after the Vs boost, all the gross tumor volume (GTV) was homogeneously treated with hypo-fractionated radiation therapy (RT). Results: The rate of symptomatic response was 100%, and it was observed immediately after lattice RT delivery in 3/30 patients, while 27/30 patients had a symptomatic response within 8 days from the end of GTV irradiation. Radiation-related acute grade ≥1 toxicities were observed in 6/30 (20%) patients. The rate of overall clinical response was 89%, including 23% of complete remission. The 1-year overall survival rate was 86.4%. Conclusions: “Metabolism-guided” lattice radiotherapy is feasible and well-tolerated, being able to yield very impressive results both in terms of symptom relief and overall clinical response rate in stage IV bulky disease patients. These preliminary results seem to indicate that this kind of therapy could emerge as the best therapeutic option for this patient setting.
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15
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Dincer N, Ugurluer G, Korkmaz L, Serkizyan A, Atalar B, Gungor G, Ozyar E. Magnetic Resonance Imaging-Guided Online Adaptive Lattice Stereotactic Body Radiotherapy in Voluminous Liver Metastasis: Two Case Reports. Cureus 2022; 14:e23980. [PMID: 35541303 PMCID: PMC9084247 DOI: 10.7759/cureus.23980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2022] [Indexed: 11/17/2022] Open
Abstract
Lattice Radiotherapy (LRT) is a technique in which heterogeneous doses are delivered to the target so large tumors can have optimal doses of radiation without compromising healthy tissue sparing. To date, case reports and case series documented its application for bulky tumors mainly in the pelvic region. LRT not only provides dosimetric advantages but also promotes tumor control by triggering some radiobiological and immunological pathways. We report two cases of giant liver metastases for whom other treatment options were not suitable. We treated both patients with Magnetic Resonance Image-Guided Radiotherapy (MRgRT) with online adaptive LRT (OALRT) technique. Adaptive plans were generated before each fraction. Tumors were observed to have regressed interfractionally so the location and number of spheres were adapted to tumor size and daily anatomy of the surrounding organs at risk (OAR). Both patients had good treatment compliance without any Grade 3+ side effects. They are both under follow-up and report improvement. By reporting the first application of OALRT by using MRgRT in liver metastases, we show that MRgRT is a promising modality for LRT technique with better target and OAR visualization as well as online adaptive planning before each fraction according to the daily anatomy of the patient.
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Affiliation(s)
- Neris Dincer
- Radiation Oncology, Acibadem University, Istanbul, TUR
| | | | - Latif Korkmaz
- Radiation Oncology, Acibadem Maslak Hospital, Istanbul, TUR
| | | | - Banu Atalar
- Radiation Oncology, Acibadem University, Istanbul, TUR
| | - Gorkem Gungor
- Radiation Oncology, Acibadem Maslak Hospital, Istanbul, TUR
| | - Enis Ozyar
- Radiation Oncology, Acibadem Mehmet Ali Aydinlar University School of Medicine, Istanbul, TUR.,Radiation Oncology, Acibadem Hospital, Istanbul, TUR
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16
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Moghaddasi L, Reid P, Bezak E, Marcu LG. Radiobiological and Treatment-Related Aspects of Spatially Fractionated Radiotherapy. Int J Mol Sci 2022; 23:3366. [PMID: 35328787 PMCID: PMC8954016 DOI: 10.3390/ijms23063366] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 03/13/2022] [Accepted: 03/17/2022] [Indexed: 11/17/2022] Open
Abstract
The continuously evolving field of radiotherapy aims to devise and implement techniques that allow for greater tumour control and better sparing of critical organs. Investigations into the complexity of tumour radiobiology confirmed the high heterogeneity of tumours as being responsible for the often poor treatment outcome. Hypoxic subvolumes, a subpopulation of cancer stem cells, as well as the inherent or acquired radioresistance define tumour aggressiveness and metastatic potential, which remain a therapeutic challenge. Non-conventional irradiation techniques, such as spatially fractionated radiotherapy, have been developed to tackle some of these challenges and to offer a high therapeutic index when treating radioresistant tumours. The goal of this article was to highlight the current knowledge on the molecular and radiobiological mechanisms behind spatially fractionated radiotherapy and to present the up-to-date preclinical and clinical evidence towards the therapeutic potential of this technique involving both photon and proton beams.
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Affiliation(s)
- Leyla Moghaddasi
- Department of Medical Physics, Austin Health, Ballarat, VIC 3350, Australia;
- School of Physical Sciences, University of Adelaide, Adelaide, SA 5001, Australia;
| | - Paul Reid
- Radiation Health, Environment Protection Authority, Adelaide, SA 5000, Australia;
| | - Eva Bezak
- School of Physical Sciences, University of Adelaide, Adelaide, SA 5001, Australia;
- Cancer Research Institute, University of South Australia, Adelaide, SA 5001, Australia
| | - Loredana G. Marcu
- Cancer Research Institute, University of South Australia, Adelaide, SA 5001, Australia
- Faculty of Informatics and Science, University of Oradea, 1 Universitatii Str., 410087 Oradea, Romania
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17
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Duriseti S, Kavanaugh JA, Szymanski J, Huang Y, Basarabescu F, Chaudhuri A, Henke L, Samson P, Lin A, Robinson C, Spraker MB. LITE SABR M1: A phase I trial of Lattice stereotactic body radiotherapy for large tumors. Radiother Oncol 2022; 167:317-322. [PMID: 34875286 DOI: 10.1016/j.radonc.2021.11.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 11/09/2021] [Accepted: 11/22/2021] [Indexed: 12/31/2022]
Abstract
PURPOSE Stereotactic body radiotherapy (SBRT) is an attractive treatment option for patients with metastatic and/or unresectable tumors, however its use is limited to smaller tumors. Lattice is a form of spatially fractionated radiotherapy that may allow safe delivery of ablative doses to bulky tumors. We previously described Lattice SBRT, which delivers 20 Gy in 5 fractions with a simultaneous integrated boost to 66.7 Gy in a defined geometric arrangement (Lattice boost). The goal of this study was to prospectively evaluate the acute toxicity and quality of life (QoL) of patients with large tumors (>5 cm) treated with Lattice SBRT. METHODS This was a single-arm phase I trial conducted between October 2019 and August 2020. Patients with tumors > 4.5 cm were eligible. Lattice SBRT was delivered every other day. The primary outcome was the rate of 90-day treatment-associated (probably or definitely attributable) grade 3 + acute toxicity by Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 criteria. Other outcomes included changes in patient reported toxicity and QoL inventories, GTV, and peripheral blood cytokines. RESULTS Twenty patients (22 tumors) were enrolled. Median GTV was 579.2 cc (range: 54.2-3713.5 cc) in volume and 11.1 cm (range: 5.6-21.4 cm) in greatest axial diameter. Fifty percent of tumors were in the thorax, 45% abdomen/pelvis, and 5% extremity. There was no likely treatment-associated grade 3 + toxicity in the 90-day period (acute and sub-acute). There was one case of grade 4 toxicity possibly associated with Lattice SBRT. CONCLUSIONS This phase I study met its primary endpoint of physician reported short-term safety. An ongoing phase II clinical trial of Lattice SBRT will evaluate late safety and efficacy of this novel technique.
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Affiliation(s)
- Sai Duriseti
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - James A Kavanaugh
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Jeff Szymanski
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Yi Huang
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Franco Basarabescu
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Aadel Chaudhuri
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Lauren Henke
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Pamela Samson
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Alexander Lin
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Clifford Robinson
- Department of Radiation Oncology, Washington University in St. Louis, United States
| | - Matthew B Spraker
- Department of Radiation Oncology, Washington University in St. Louis, United States.
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