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Alexander NA, Schaub SK, Goff PH, Hippe DS, Park SY, Lachance K, Bierma M, Liao JJ, Apisarnthanarax S, Bhatia S, Tseng YD, Nghiem PT, Parvathaneni U. Increased risk of recurrence and disease-specific death following delayed postoperative radiation for Merkel cell carcinoma. J Am Acad Dermatol 2024; 90:261-268. [PMID: 37778663 DOI: 10.1016/j.jaad.2023.07.1047] [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: 01/13/2023] [Revised: 06/09/2023] [Accepted: 07/27/2023] [Indexed: 10/03/2023]
Abstract
BACKGROUND Merkel cell carcinoma (MCC) is often treated with surgery and postoperative radiation therapy (PORT). The optimal time to initiate PORT (Time-to-PORT [ttPORT]) is unknown. PURPOSE We assessed if delays in ttPORT were associated with inferior outcomes. METHODS Competing risk regression was used to evaluate associations between ttPORT and locoregional recurrence (LRR) for patients with stage I/II MCC in a prospective registry and adjust for covariates. Distant metastasis and death were competing risks. RESULTS The cohort included 124 patients with median ttPORT of 41 days (range: 8-125 days). Median follow-up was 55 months. 17 (14%) patients experienced a LRR, 14 (82%) of which arose outside the radiation field. LRR at 5 years was increased for ttPORT >8 weeks vs ≤ 8 weeks, 28.0% vs 9.2%, P = .006. There was an increase in the cumulative incidence of MCC-specific death with increasing ttPORT (HR = 1.14 per 1-week increase, P = .016). LIMITATIONS The relatively low number of LRRs limited the extent of our multivariable analyses. CONCLUSIONS Delay of PORT was associated with increased LRR, usually beyond the radiation field. This is consistent with the tendency of MCC to spread quickly via lymphatics. Initiation of PORT within 8 weeks was associated with improved locoregional control and MCC-specific survival.
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Affiliation(s)
- Nora A Alexander
- Department of Dermatology, University of Washington, Seattle, Washington; Division of Dermatology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Stephanie K Schaub
- Department of Radiation Oncology, University of Washington, Seattle, Washington; Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, Washington.
| | - Peter H Goff
- Department of Radiation Oncology, University of Washington, Seattle, Washington
| | - Daniel S Hippe
- Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Song Y Park
- Department of Dermatology, University of Washington, Seattle, Washington
| | - Kristina Lachance
- Department of Dermatology, University of Washington, Seattle, Washington
| | - Marika Bierma
- Department of Dermatology, University of Washington, Seattle, Washington
| | - Jay J Liao
- Department of Radiation Oncology, University of Washington, Seattle, Washington
| | | | - Shailender Bhatia
- Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, Washington; Division of Medical Oncology, Department of Medicine, University of Washington, Seattle, Washington
| | - Yolanda D Tseng
- Department of Radiation Oncology, University of Washington, Seattle, Washington; Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Paul T Nghiem
- Department of Dermatology, University of Washington, Seattle, Washington
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Celikdemir B, Houben R, Kervarrec T, Samimi M, Schrama D. Current and preclinical treatment options for Merkel cell carcinoma. Expert Opin Biol Ther 2023; 23:1015-1034. [PMID: 37691397 DOI: 10.1080/14712598.2023.2257603] [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: 03/28/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 09/12/2023]
Abstract
INTRODUCTION Merkel cell carcinoma (MCC) is a rare, highly aggressive form of skin cancer with neuroendocrine features. The origin of this cancer is still unclear, but research in the last 15 years has demonstrated that MCC arises via two distinct etiologic pathways, i.e. virus and UV-induced. Considering the high mortality rate and the limited therapeutic options available, this review aims to highlight the significance of MCC research and the need for advancement in MCC treatment. AREAS COVERED With the advent of the immune checkpoint inhibitor therapies, we now have treatment options providing a survival benefit for patients with advanced MCC. However, the issue of primary and acquired resistance to these therapies remains a significant concern. Therefore, ongoing efforts seeking additional therapeutic targets and approaches for MCC therapy are a necessity. Through a comprehensive literature search, we provide an overview on recent preclinical and clinical studies with respect to MCC therapy. EXPERT OPINION Currently, the only evidence-based therapy for MCC is immune checkpoint blockade with anti-PD-1/PD-L1 for advanced patients. Neoadjuvant, adjuvant and combined immune checkpoint blockade are promising treatment options.
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Affiliation(s)
- Büke Celikdemir
- Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
| | - Roland Houben
- Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
| | - Thibault Kervarrec
- Department of Pathology, Centre Hospitalier Universitaire De Tours, Tours, France
| | - Mahtab Samimi
- Department of Dermatology, University Hospital of Tours, Tours, France
| | - David Schrama
- Department of Dermatology, Venereology and Allergology, University Hospital Würzburg, Würzburg, Germany
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Gordon K, Gulidov I, Fatkhudinov T, Koryakin S, Kaprin A. Fast and Furious: Fast Neutron Therapy in Cancer Treatment. Int J Part Ther 2022; 9:59-69. [PMID: 36060415 PMCID: PMC9415749 DOI: 10.14338/ijpt-22-00017] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/17/2022] [Indexed: 11/21/2022] Open
Abstract
Fast neutron therapy has been used for decades. In conjunction with recent advances in photonic techniques, fast neutrons are no longer of much oncologic interest, which is not unequivocally positive, given their undoubted therapeutic value. This mini-review recalls the history of medical research on fast neutrons, considers their physical and radiobiological properties alongside their benefits for cancer treatment, and discusses their place in modern radiation oncology.
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Affiliation(s)
- Konstantin Gordon
- 1 Federal State Autonomous Educational Institution of Higher Education “People's Friendship University of Russia,” Medical Institution, Moscow, Russia
- 2 A. Tsyb Medical Radiological Research Center—branch of the National Medical Research Radiological Center of the Ministry of Health of the Russian Federation, Obninsk, Russia
| | - Igor Gulidov
- 2 A. Tsyb Medical Radiological Research Center—branch of the National Medical Research Radiological Center of the Ministry of Health of the Russian Federation, Obninsk, Russia
| | - Timur Fatkhudinov
- 1 Federal State Autonomous Educational Institution of Higher Education “People's Friendship University of Russia,” Medical Institution, Moscow, Russia
| | - Sergey Koryakin
- 2 A. Tsyb Medical Radiological Research Center—branch of the National Medical Research Radiological Center of the Ministry of Health of the Russian Federation, Obninsk, Russia
| | - Andrey Kaprin
- 1 Federal State Autonomous Educational Institution of Higher Education “People's Friendship University of Russia,” Medical Institution, Moscow, Russia
- 2 A. Tsyb Medical Radiological Research Center—branch of the National Medical Research Radiological Center of the Ministry of Health of the Russian Federation, Obninsk, Russia
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The behavior of the contamination particles appears with the 18 MV photon beam delivered by Elekta Synergy MLCi2. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ricco G, Andrini E, Siepe G, Mosconi C, Ambrosini V, Ricci C, Casadei R, Campana D, Lamberti G. Multimodal Strategy in Localized Merkel Cell Carcinoma: Where Are We and Where Are We Heading? Int J Mol Sci 2021; 22:ijms221910629. [PMID: 34638968 PMCID: PMC8508588 DOI: 10.3390/ijms221910629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 02/07/2023] Open
Abstract
Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumor of the skin whose incidence is rising. Multimodal treatment is crucial in the non-metastatic, potentially curable setting. However, the optimal management of patients with non-metastatic MCC is still unclear. In addition, novel insights into tumor biology and newly developed treatments (e.g., immune checkpoint inhibitors) that dramatically improved outcomes in the advanced setting are being investigated in earlier stages with promising results. Nevertheless, the combination of new strategies with consolidated ones needs to be clarified. We reviewed available evidence supporting the current treatment recommendations of localized MCC with a focus on potentially ground-breaking future strategies. Advantages and disadvantages of the different treatment modalities, including surgery, radiotherapy, chemotherapy, and immunotherapy in the non-metastatic setting, are analyzed, as well as those of different treatment modalities (adjuvant as opposed to neoadjuvant). Lastly, we provide an outlook of remarkable ongoing studies and of promising agents and strategies in the treatment of patients with non-metastatic MCC.
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Affiliation(s)
- Gianluca Ricco
- Department of Experimental Diagnostic and Specialized Medicine (DIMES), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy; (G.R.); (E.A.); (V.A.); (G.L.)
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
| | - Elisa Andrini
- Department of Experimental Diagnostic and Specialized Medicine (DIMES), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy; (G.R.); (E.A.); (V.A.); (G.L.)
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
| | - Giambattista Siepe
- Radiation Oncology, IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40138 Bologna, Italy;
| | - Cristina Mosconi
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
- Department of Radiology, IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40138 Bologna, Italy
| | - Valentina Ambrosini
- Department of Experimental Diagnostic and Specialized Medicine (DIMES), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy; (G.R.); (E.A.); (V.A.); (G.L.)
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
- IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40139 Bologna, Italy
| | - Claudio Ricci
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
- IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40139 Bologna, Italy
- Department of Internal Medicine and Surgery (DIMEC), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy
| | - Riccardo Casadei
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
- IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40139 Bologna, Italy
- Department of Internal Medicine and Surgery (DIMEC), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy
| | - Davide Campana
- Department of Experimental Diagnostic and Specialized Medicine (DIMES), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy; (G.R.); (E.A.); (V.A.); (G.L.)
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
- Division of Medical Oncology, IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40138 Bologna, Italy
- Correspondence: ; Tel.: +39-051-2142886
| | - Giuseppe Lamberti
- Department of Experimental Diagnostic and Specialized Medicine (DIMES), Alma Mater Studiorum, University of Bologna, 40138 Bologna, Italy; (G.R.); (E.A.); (V.A.); (G.L.)
- NET Team Bologna—ENETS Center of Excellence, 40138 Bologna, Italy; (C.M.); (C.R.); (R.C.)
- Division of Medical Oncology, IRCCS Azienda Ospedaliero—Universitaria di Bologna, 40138 Bologna, Italy
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Marchand A, Kervarrec T, Bhatia S, Samimi M. Pembrolizumab and other immune checkpoint inhibitors in locally advanced or metastatic Merkel Cell Carcinoma: safety and efficacy. Expert Rev Anticancer Ther 2020; 20:1093-1106. [PMID: 33044876 DOI: 10.1080/14737140.2021.1835477] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Merkel Cell Carcinoma (MCC) is a rare aggressive skin cancer, mostly affecting elderly patients. Until recently, patients with advanced disease were treated with cytotoxic chemotherapies despite rapid chemoresistance and high toxicity. As with other cancers, immune checkpoint inhibitors (CPI), including pembrolizumab, allow durable responses with a manageable safety profile in these patients. AREAS COVERED This review describes the rationale for using PD-1/PD-L1 inhibitors in MCC, as well as efficacy and safety results from the three open-label trials investigating pembrolizumab or other PD-1/PD-L1 inhibitors in patients with advanced MCC. Real-life experience and predictive pre-treatment biomarkers are discussed to assess which patients are likely to be candidates for such strategies. Ongoing fields of research include the use of CPI in the adjuvant or neoadjuvant setting and combined strategies in refractory patients. Expert Opinion: CPI have become the standard of care for frontline treatment in patients with advanced MCC. Earlier introduction of CPI in the disease course, including neo-adjuvant and adjuvant settings, is likely to improve the outcomes further. Given the rarity of this cancer, we still need to harmonize efforts in order to conduct large-scale trials and efficiently identify best optimal care.
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Affiliation(s)
- Antoine Marchand
- Dermatology Department, University Hospital of Tours , Tours, France
| | - Thibault Kervarrec
- Pathology Department, University Hospital of Tours , Tours, France.,BIP (Biology of Polyomaviruses), ISP1282 INRA-University of Tours , Tours, France
| | - Shailender Bhatia
- Department of Medicine/Medical Oncology, University of Washington Medical Center , Seattle, Washington, USA.,Clinical Research Division, Fred Hutchinson Cancer Research Center , Seattle, Washington, USA
| | - Mahtab Samimi
- Dermatology Department, University Hospital of Tours , Tours, France.,BIP (Biology of Polyomaviruses), ISP1282 INRA-University of Tours , Tours, France
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Tabachnick-Cherny S, Pulliam T, Church C, Koelle DM, Nghiem P. Polyomavirus-driven Merkel cell carcinoma: Prospects for therapeutic vaccine development. Mol Carcinog 2020; 59:807-821. [PMID: 32219902 PMCID: PMC8238237 DOI: 10.1002/mc.23190] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/06/2020] [Accepted: 03/07/2020] [Indexed: 12/15/2022]
Abstract
Great strides have been made in cancer immunotherapy including the breakthrough successes of anti-PD-(L)1 checkpoint inhibitors. In Merkel cell carcinoma (MCC), a rare and aggressive skin cancer, PD-(L)1 blockade is highly effective. Yet, ~50% of patients either do not respond to therapy or develop PD-(L)1 refractory disease and, thus, do not experience long-term benefit. For these patients, additional or combination therapies are needed to augment immune responses that target and eliminate cancer cells. Therapeutic vaccines targeting tumor-associated antigens, mutated self-antigens, or immunogenic viral oncoproteins are currently being developed to augment T-cell responses. Approximately 80% of MCC cases in the United States are driven by the ongoing expression of viral T-antigen (T-Ag) oncoproteins from genomically integrated Merkel cell polyomavirus (MCPyV). Since T-Ag elicits specific B- and T-cell immune responses in most persons with virus-positive MCC (VP-MCC), and ongoing T-Ag expression is required to drive VP-MCC cell proliferation, therapeutic vaccination with T-Ag is a rational potential component of immunotherapy. Failure of the endogenous T-cell response to clear VP-MCC (allowing clinically evident tumors to arise) implies that therapeutic vaccination will need to be potent anśd synergize with other mechanisms to enhance T-cell activity against tumor cells. Here, we review the relevant underlying biology of VP-MCC, potentially applicable therapeutic vaccine platforms, and antigen delivery formats. We also describe early successes in the field of therapeutic cancer vaccines and address several clinical scenarios in which VP-MCC patients could potentially benefit from a therapeutic vaccine.
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Affiliation(s)
- Shira Tabachnick-Cherny
- Department of Medicine, Division of Dermatology, University of Washington, Seattle, Washington
| | - Thomas Pulliam
- Department of Medicine, Division of Dermatology, University of Washington, Seattle, Washington
| | - Candice Church
- Department of Medicine, Division of Dermatology, University of Washington, Seattle, Washington
| | - David M Koelle
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington
- Translational Research Program, Benaroya Research Institute at Virginia Mason, Seattle, Washington
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
- Department of Global Health, University of Washington, Seattle, Washington
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Paul Nghiem
- Department of Medicine, Division of Dermatology, University of Washington, Seattle, Washington
- Seattle Cancer Care Alliance, Seattle, Washington
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
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Determination of fast neutron RBE using a fully mechanistic computational model. Appl Radiat Isot 2020; 156:108952. [DOI: 10.1016/j.apradiso.2019.108952] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/11/2019] [Accepted: 10/21/2019] [Indexed: 11/19/2022]
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Zabihi A, Incerti S, Francis Z, Forozani G, Semsarha F, Moslehi A, Rezaeian P, Bernal MA. Computational approach to determine the relative biological effectiveness of fast neutrons using the Geant4-DNA toolkit and a DNA atomic model from the Protein Data Bank. Phys Rev E 2019; 99:052404. [PMID: 31212425 DOI: 10.1103/physreve.99.052404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Indexed: 11/07/2022]
Abstract
This study proposes an innovative approach to estimate relative biological effectiveness (RBE) of fast neutrons using the Geant4 toolkit. The Geant4-DNA version cannot track heavy ions below 0.5 MeV/nucleon. In order to explore the impact of this issue, secondary particles are simulated instead of the primary low-energy neutrons. The Evaluated Nuclear Data File library is used to determine the cross sections for the elastic and inelastic interactions of neutrons with water and to find the contribution of each secondary particle spectrum. Two strategies are investigated in order to find the best possible approach and results. The first one takes into account only light particles, protons produced from elastic scattering, and α particles from inelastic scattering. Geantino particles are shot instead of heavy ions; hence all heavy ions are considered in the simulations, though their physical effects on DNA not. The second strategy takes into account all the heavy and light ions, although heavy ions cannot be tracked down to very low energies (E<0.5 MeV/nucleon). Our model is based on the combination of an atomic resolution DNA geometrical model and a Monte Carlo simulation toolkit for tracking particles. The atomic coordinates of the DNA double helix are extracted from the Protein Data Bank. Since secondary particle spectra are used instead of simulating the interaction of neutrons explicitly, this method reduces the computation times dramatically. Double-strand break induction is used as the end point for the estimation of the RBE of fast neutrons. ^{60}Co γ rays are used as the reference radiation quality. Both strategies succeed in reproducing the behavior of the RBE_{max} as a function of the incident neutron energy ranging from 0.1 to 14 MeV, including the position of its peak. A comparison of the behavior of the two strategies shows that for neutrons with energies less than 0.7 MeV, the effect of heavy ions would not be very significant, but above 0.7 MeV, heavy ions have an important role in neutron RBE.
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Affiliation(s)
- Azam Zabihi
- Department of Physics, Faculty of Science, Bu-Ali Sina University, Hamedan 651744161, Iran
| | - Sebastien Incerti
- University of Bordeaux, CENBG, UMR No. 5797, 33170 Gradignan, France CNRS, IN2P3, CENBG, UMR No. 5797, 33170 Gradignan, France
| | - Ziad Francis
- Department of Physics, Faculty of Sciences, Université Saint Joseph, 2020 1104 Beirut, Lebanon
| | - Ghasem Forozani
- Department of Physics, Payame Noor University, P.O. Box 19395-3697, Tehran, Iran
| | - Farid Semsarha
- Institute of Biochemistry and Biophysics, University of Tehran, P.O. Box 13145-1384, Tehran, Iran
| | - Amir Moslehi
- Radiation Applications Research School, Nuclear Science and Technology Research Institute, P.O. Box 11365-3486, Tehran, Iran
| | - Peiman Rezaeian
- Radiation Applications Research School, Nuclear Science and Technology Research Institute, P.O. Box 11365-3486, Tehran, Iran
| | - Mario A Bernal
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo, Brazil
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The systemic immunostimulatory effects of radiation therapy producing overall tumor control through the abscopal effect. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s13566-019-00391-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Abstract
Purpose: Neutrons were an active field of radiobiology at the time of publication of the first issues of the International Journal of Radiation Biology in 1959. Three back-to-back papers published by Neary and his colleagues contain key elements of interest at the time. The present article aims to put these papers into context with the discovery of the neutron 27 years previously and then give a feel for how the field has progressed to the present day. It does not intend to provide a comprehensive review of this enormous field, but rather to provide selective summaries of main driving forces and developments. Conclusions: Neutron radiobiology has continued as a vigorous field of study throughout the past 84 years. Main driving forces have included concern for protection from the harmful effects of neutrons, exploitation and optimization for cancer therapy (fast beam therapy, brachytherapy and boron capture therapy), and scientific curiosity about the mechanisms of radiation action. Effort has fluctuated as the emphasis has shifted from time to time, but all three areas remain active today. Whatever the future holds for the various types of neutron therapy, the health protection aspects will remain with us permanently because of natural environmental exposure to neutrons as well as increased additional exposures from a variety of human activities.
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Stewart RD, Carlson DJ, Butkus MP, Hawkins R, Friedrich T, Scholz M. A comparison of mechanism-inspired models for particle relative biological effectiveness (RBE). Med Phys 2018; 45:e925-e952. [PMID: 30421808 DOI: 10.1002/mp.13207] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND SIGNIFICANCE The application of heavy ion beams in cancer therapy must account for the increasing relative biological effectiveness (RBE) with increasing penetration depth when determining dose prescriptions and organ at risk (OAR) constraints in treatment planning. Because RBE depends in a complex manner on factors such as the ion type, energy, cell and tissue radiosensitivity, physical dose, biological endpoint, and position within and outside treatment fields, biophysical models reflecting these dependencies are required for the personalization and optimization of treatment plans. AIM To review and compare three mechanism-inspired models which predict the complexities of particle RBE for various ion types, energies, linear energy transfer (LET) values and tissue radiation sensitivities. METHODS The review of models and mechanisms focuses on the Local Effect Model (LEM), the Microdosimetric-Kinetic (MK) model, and the Repair-Misrepair-Fixation (RMF) model in combination with the Monte Carlo Damage Simulation (MCDS). These models relate the induction of potentially lethal double strand breaks (DSBs) to the subsequent interactions and biological processing of DSB into more lethal forms of damage. A key element to explain the increased biological effectiveness of high LET ions compared to MV x rays is the characterization of the number and local complexity (clustering) of the initial DSB produced within a cell. For high LET ions, the spatial density of DSB induction along an ion's trajectory is much greater than along the path of a low LET electron, such as the secondary electrons produced by the megavoltage (MV) x rays used in conventional radiation therapy. The main aspects of the three models are introduced and the conceptual similarities and differences are critiqued and highlighted. Model predictions are compared in terms of the RBE for DSB induction and for reproductive cell survival. RESULTS AND CONCLUSIONS Comparisons of the RBE for DSB induction and for cell survival are presented for proton (1 H), helium (4 He), and carbon (12 C) ions for the therapeutically most relevant range of ion beam energies. The reviewed models embody mechanisms of action acting over the spatial scales underlying the biological processing of potentially lethal DSB into more lethal forms of damage. Differences among the number and types of input parameters, relevant biological targets, and the computational approaches among the LEM, MK and RMF models are summarized and critiqued. Potential experiments to test some of the seemingly contradictory aspects of the models are discussed.
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Affiliation(s)
- Robert D Stewart
- Department of Radiation Oncology, University of Washington School of Medicine, 1959 NE Pacific Street, Box 356043, Seattle, WA, 98195, USA
| | - David J Carlson
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Michael P Butkus
- Department of Therapeutic Radiology, Yale University, New Haven, CT, USA
| | - Roland Hawkins
- Radiation Oncology Center, Ochsner Clinic Foundation, New Orleans, LA, 70121, USA
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