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Nuyts S, Bollen H, Eisbruch A, Strojan P, Mendenhall WM, Ng SP, Ferlito A. Adaptive radiotherapy for head and neck cancer: Pitfalls and possibilities from the radiation oncologist's point of view. Cancer Med 2024; 13:e7192. [PMID: 38650546 PMCID: PMC11036082 DOI: 10.1002/cam4.7192] [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: 01/11/2024] [Revised: 03/19/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND Patients with head and neck cancer (HNC) may experience substantial anatomical changes during the course of radiotherapy treatment. The implementation of adaptive radiotherapy (ART) proves effective in managing the consequent impact on the planned dose distribution. METHODS This narrative literature review comprehensively discusses the diverse strategies of ART in HNC and the documented dosimetric and clinical advantages associated with these approaches, while also addressing the current challenges for integration of ART into clinical practice. RESULTS AND CONCLUSION Although based on mainly non-randomized and retrospective trials, there is accumulating evidence that ART has the potential to reduce toxicity and improve quality of life and tumor control in HNC patients treated with RT. However, several questions remain regarding accurate patient selection, the ideal frequency and timing of replanning, and the appropriate way for image registration and dose calculation. Well-designed randomized prospective trials, with a predetermined protocol for both image registration and dose summation, are urgently needed to further investigate the dosimetric and clinical benefits of ART.
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Affiliation(s)
- Sandra Nuyts
- Laboratory of Experimental Radiotherapy, Department of OncologyKU LeuvenLeuvenBelgium
- Department of Radiation OncologyLeuven Cancer Institute, University Hospitals LeuvenLeuvenBelgium
| | - Heleen Bollen
- Laboratory of Experimental Radiotherapy, Department of OncologyKU LeuvenLeuvenBelgium
- Department of Radiation OncologyLeuven Cancer Institute, University Hospitals LeuvenLeuvenBelgium
| | - Avrahram Eisbruch
- Department of Radiation OncologyUniversity of MichiganAnn ArborMichiganUSA
| | - Primoz Strojan
- Department of Radiation Oncology Institute of OncologyUniversity of LjubljanaLjubljanaSlovenia
| | - William M. Mendenhall
- Department of Radiation OncologyUniversity of Florida College of MedicineGainesvilleFloridaUSA
| | - Sweet Ping Ng
- Department of Radiation OncologyOlivia Newton‐John Cancer and Wellness Centre, Austin HealthMelbourneAustralia
| | - Alfio Ferlito
- Coordinator International Head and Neck Scientific GroupUdineItaly
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Yan D, Yin X, Wang L, Huang L, Tang Q, Cheng K, Yan S. Induction chemotherapy reduces target volume drift in patients with locoregionally advanced nasopharyngeal carcinoma undergoing adaptive intensity-modulated radiotherapy: a retrospective cohort study. Quant Imaging Med Surg 2023; 13:1779-1791. [PMID: 36915305 PMCID: PMC10006138 DOI: 10.21037/qims-22-776] [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: 08/09/2022] [Accepted: 01/19/2023] [Indexed: 02/23/2023]
Abstract
Background Adaptive radiotherapy (ART) provides real-time correction of the target and dose of radiation based on repeat computed tomography (CT) imaging and replanning during intensity-modulated radiation therapy (IMRT) and is important for locoregionally advanced nasopharyngeal carcinoma (NPC). However, repeat CT imaging and replanning are time-consuming and hinder the broader application of ART. The optimum dose and frequency of replanning time have been published in previous reports. The purpose of this study was to determine whether induction chemotherapy (IC) reduces target volume drift during IMRT, potentially reducing the replanning workload. Methods From January 2012 to December 2017, 40 patients with locoregionally advanced, nonmetastatic stage III-IVa NPC treated in the Department of Radiation Oncology in the First Affiliated Hospital, College of Medicine, Zhejiang University, were enrolled into this study. Of the 40 patients, 20 received 2-3 cycles of IC before concurrent chemoradiotherapy (IC + CCRT), and the other 20 patients were treated with CCRT plus adjuvant chemotherapy (CCRT + AC). During CCRT, all patients underwent weekly simulated CT for 6 weeks. The gross tumor volume (GTV), clinical target volume (CTV), and body weight were measured weekly and compared between the 2 groups. Results Compared with the baseline, the mean weight loss after 25 fractions was 7.0 kg (13.6%; range, 3.9-25.5%) in the CCRT + AC group and 5.7 kg (8.3%; range, 3.6-20%) in the IC + CCRT group. The mean GTV and CTV decreased by 16.55 mL (15.7%; range, 6.1-33.7%) and 61.25 mL (9.33%; range, 4.4-17.0%), respectively, in the IC + CCRT group, and by 39.86 mL (38.79%; range, 25.3-50.7%) and 87.72 mL (12.7%; range, 6.7-22.9%), respectively, in the CCRT + AC group. The degree of weekly reduction in the GTV of the IC + CCRT group was not significantly higher than that of the CCRT + AC group, with the following P values of each percentage reduction in comparison with the previous week over 5 weeks, respectively: P<0.001, P=0.015, P=0.01, P=0.01, and P<0.001. The weekly CTV reduction only significantly correlated with weight loss (P=0.005) in the IC + CCRT group. Conclusions IC significantly decreased the degree of weight loss, GTV shrinkage, and CTV reduction during CCRT, consequently decreasing the anatomical and target dose drift during the adaptive replanning of IMRT. This may lead to a reduction in the recurrence of locoregionally advanced NPC, especially among patients with large metastatic cervical lymph nodes, potentially improving survival. This result provides favorable evidence that IC improves locoregional recurrence-free survival (LRFS) and overall survival (OS) in patients with locoregionally advanced NPC.
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Affiliation(s)
- Danfang Yan
- Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Xin Yin
- Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Lihong Wang
- Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Liming Huang
- Department of Chemotherapy, People's Hospital of Fujian Province, Fuzhou, China
| | - Qiuying Tang
- Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Kejia Cheng
- Department of Otolaryngology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
| | - Senxiang Yan
- Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China
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Wu J, Qiao H. Medical Imaging Technology and Imaging Agents. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1199:15-38. [PMID: 37460725 DOI: 10.1007/978-981-32-9902-3_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2023]
Abstract
Medical imaging is a technology that studies the interaction between human body and irradiations of X-ray, ultrasound, magnetic field, etc. and represents anatomical structures of human organs/tissues with the implication of irradiation attenuation in the form of grayscales. With these medical images, detailed information on health status and disease diagnosis may be judged by clinical physicians to determine an appropriate therapy approach. This chapter will give a systematic introduction on the modalities, classifications, basic principles, and biomedical applications of traditional medical imaging along with the types, construction, and major features of the corresponding contrast agents or imaging probes.
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Affiliation(s)
- Jieting Wu
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
| | - Huanhuan Qiao
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China.
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Reinders FCJ, Stijnman PRS, de Ridder M, Doornaert PAH, Raaijmakers CPJ, Philippens MEP. MRI visibility and displacement of elective lymph nodes during radiotherapy in head and neck cancer patients. FRONTIERS IN RADIOLOGY 2022; 2:1033521. [PMID: 37492674 PMCID: PMC10365081 DOI: 10.3389/fradi.2022.1033521] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/27/2022] [Indexed: 07/27/2023]
Abstract
Background and purpose To decrease the impact of radiotherapy to healthy tissues in the head and neck region, we propose to restrict the elective neck irradiation to elective lymph nodes at risk of containing micro metastases instead of the larger lymph node volumes. To assess whether this new concept is achievable in the clinic, we determined the number, volume changes and displacement of elective lymph nodes during the course of radiotherapy. Materials and methods MRI scans of 10 head and neck cancer (HNC) patients were acquired before radiotherapy and in week 2, 3, 4 and 5 during radiotherapy. The weekly delineations of elective lymph nodes inside the lymph node levels (Ib/II/III/IVa/V) were rigidly registered and analyzed regarding number and volume. The displacement of elective lymph nodes was determined by center of mass (COM) distances, vector-based analysis and the isotropic contour expansion of the lymph nodes of the pre-treatment scan or the scan of the previous week in order to geographically cover 95% of the lymph nodes in the scans of the other weeks. Results On average, 31 elective lymph nodes in levels Ib-V on each side of the neck were determined. This number remained constant throughout radiotherapy in most lymph node levels. The volume of the elective lymph nodes reduced significantly in all weeks, up to 50% in week 5, compared to the pre-treatment scan. The largest median COM displacements were seen in level V, for example 5.2 mm in week 5 compared to the pre-treatment scan. The displacement of elective lymph nodes was mainly in cranial direction. Geographical coverage was obtained when the lymph node volumes were expanded with 7 mm in case the pre-treatment scan was used and 6.5 mm in case the scan of the previous week was used. Conclusion Elective lymph nodes of HNC patients remained visible on MRI and decreased in size during radiotherapy. The displacement of elective lymph nodes differ per lymph node level and were mainly directed cranially. Weekly adaptation does not seem to improve coverage of elective lymph nodes. Based on our findings we expect elective lymph node irradiation is achievable in the clinic.
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Affiliation(s)
- Floris C J Reinders
- Department of Radiotherapy, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Peter R S Stijnman
- Department of Radiotherapy, University Medical Centre Utrecht, Utrecht, Netherlands
| | - Mischa de Ridder
- Department of Radiotherapy, University Medical Centre Utrecht, Utrecht, Netherlands
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Adaptive radiation therapy: When, how and what are the benefits that literature provides? Cancer Radiother 2021; 26:622-636. [PMID: 34688548 DOI: 10.1016/j.canrad.2021.08.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 08/21/2021] [Accepted: 08/24/2021] [Indexed: 11/21/2022]
Abstract
PURPOSE To identify from the current literature when is the right time to replan and to assign thresholds for the optimum process of replanning. Nowadays, adaptive radiotherapy (ART) for head and neck cancer plays an exceptional role consisting of an evaluation procedure of the prominent anatomical and dosimetric variations. By performing complex radiotherapy methods, the credibility of the therapeutic result is crucial. Image guided radiotherapy (IGRT) was developed to ensure locoregional control and thus changes that might occur during radiotherapy be dealt with. MATERIALS AND METHODS An electronic research of articles published in PubMed/MEDLINE and Science Direct databases from January 2004 to October 2020 was performed. Among a total of 127 studies assessed for eligibility, 85 articles were ultimately retained for the review. RESULTS The most noticeable changes have been reported in the middle fraction of the treatment. Therefore, the suggested optimal time to replan is between the third and the fourth week. Anatomical deviations>1cm in the external contour, average weight loss>10%, violation in the dose coverage of the targets>5%, and violation in the dose of the peripherals were some of the thresholds that are currently used, and which lead to replanning. CONCLUSION ART may decrease toxicity and improve local-control. Whether it is beneficial or not, depends ultimately on each patient. However, more investigation of the changes should be performed in future prospective studies to obtain more accurate results.
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Chen YP, Ismaila N, Chua MLK, Colevas AD, Haddad R, Huang SH, Wee JTS, Whitley AC, Yi JL, Yom SS, Chan ATC, Hu CS, Lang JY, Le QT, Lee AWM, Lee N, Lin JC, Ma B, Morgan TJ, Shah J, Sun Y, Ma J. Chemotherapy in Combination With Radiotherapy for Definitive-Intent Treatment of Stage II-IVA Nasopharyngeal Carcinoma: CSCO and ASCO Guideline. J Clin Oncol 2021; 39:840-859. [PMID: 33405943 DOI: 10.1200/jco.20.03237] [Citation(s) in RCA: 154] [Impact Index Per Article: 51.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE The aim of this joint guideline is to provide evidence-based recommendations to practicing physicians and other healthcare providers on definitive-intent chemoradiotherapy for patients with stage II-IVA nasopharyngeal carcinoma (NPC). METHODS The Chinese Society of Clinical Oncology (CSCO) and ASCO convened an expert panel of radiation oncology, medical oncology, surgery, and advocacy representatives. The literature search included systematic reviews, meta-analyses, and randomized controlled trials published from 1990 through 2020. Outcomes of interest included survival, distant and locoregional disease control, and quality of life. Expert panel members used this evidence and informal consensus to develop evidence-based guideline recommendations. RESULTS The literature search identified 108 relevant studies to inform the evidence base for this guideline. Five overarching clinical questions were addressed, which included subquestions on radiotherapy (RT), chemotherapy sequence, and concurrent, induction, and adjuvant chemotherapy options. RECOMMENDATIONS Evidence-based recommendations were developed to address aspects of care related to chemotherapy in combination with RT for the definitive-intent treatment of stage II to IVA NPC.Additional information is available at www.asco.org/head-neck-cancer-guidelines.
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Affiliation(s)
- Yu-Pei Chen
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangzhou, and Chinese Society of Clinical Oncology, Beijing, People's Republic of China
| | | | - Melvin L K Chua
- National Cancer Centre Singapore/Duke-NUS Medical School, Singapore
| | | | | | - Shao Hui Huang
- Princess Margaret Cancer Centre/University of Toronto, Toronto, Ontario, Canada
| | - Joseph T S Wee
- National Cancer Centre Singapore/Duke-NUS Medical School, Singapore
| | | | - Jun-Lin Yi
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, and Chinese Society of Clinical Oncology, Beijing, People's Republic of China
| | - Sue S Yom
- University of California San Francisco, San Francisco, CA
| | - Anthony T C Chan
- State Key Laboratory of Translational Oncology, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute, The Chinese University of Hong Kong, Hong Kong, Special Administrative Region, People's Republic of China
| | - Chao-Su Hu
- Fudan University Shanghai Cancer Center, Shanghai, and Chinese Society of Clinical Oncology, Beijing, People's Republic of China
| | - Jin-Yi Lang
- Sichuan Cancer Hospital & Institute, Chengdu, and Chinese Society of Clinical Oncology, Beijing, People's Republic of China
| | - Quynh-Thu Le
- Stanford University School of Medicine, Stanford, CA
| | - Anne W M Lee
- The University of Hong Kong-Shenzhen Hospital, People's Republic of China, and The University of Hong Kong, Hong Kong, Special Administrative Region, People's Republic of China
| | - Nancy Lee
- Memorial Sloan Kettering Cancer Center, New York, NY
| | | | - Brigette Ma
- State Key Laboratory of Translational Oncology, Sir YK Pao Centre for Cancer, Department of Clinical Oncology, Hong Kong Cancer Institute, The Chinese University of Hong Kong, Hong Kong, Special Administrative Region, People's Republic of China
| | | | - Jatin Shah
- Memorial Sloan Kettering Cancer Center, New York, NY
| | - Ying Sun
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangzhou, and Chinese Society of Clinical Oncology, Beijing, People's Republic of China
| | - Jun Ma
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Guangzhou, and Chinese Society of Clinical Oncology, Beijing, People's Republic of China
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Zhang L, Ye Z, Ruan L, Jiang M. Pretreatment MRI-Derived Radiomics May Evaluate the Response of Different Induction Chemotherapy Regimens in Locally advanced Nasopharyngeal Carcinoma. Acad Radiol 2020; 27:1655-1664. [PMID: 33004261 DOI: 10.1016/j.acra.2020.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/01/2020] [Accepted: 09/03/2020] [Indexed: 01/04/2023]
Abstract
RATIONALE AND OBJECTIVES To evaluate and compare the performance of radiomics in predicting induction chemotherapy response treated with two different regimens in patients with advanced nasopharyngeal carcinoma. MATERIALS AND METHODS A total of 265 patients with pathologically confirmed locally advanced nasopharyngeal carcinoma (stage II-IV), including 115 treated with gemcitabine plus cisplatin (GP group) and 150 treated with docetaxel plus cisplatin (TP group) were retrospectively enrolled. Radiomics features were extracted from the volume of interest delineated in multi-MR sequences on a 3T scanner. After random stratified grouping (training and validation cohorts) and logistic regression based on selected features, the association between the radiomics signature and the early response to induction chemotherapy were established for GP and TP regiments, respectively. RESULTS Clinical factors showed no significant difference between the response and non-response groups for the GP and TP regiments (all p > 0.05). The accuracy of the radiomics signature consisting of selected features from the joint T1, T2, and T1C in the GP group (0.852 in the training cohort vs. 0.853 in the validation cohort) was significantly higher than that in the TP group (0.774 vs 0.727). The overall performance of the GP model was steady, with efficiency to distinguish responders from nonresponders with an AUC reaching 0.907 (95% confidence interval [CI] [0.843-0.970]) in the training cohort and 0.886 (95% CI [0.772-0.998]) in the validation cohort, while leveling at 0.800 (95% CI [0.712-0.888]) in the training cohort and 0.863 (95% CI [0.758-0.967]) in the validation cohort in the TP group. CONCLUSION Pretreatment MR radiomics signature can better predict the early response to IC in the GP regimen than the TP regimen, which may be helpful to guide IC management.
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Affiliation(s)
- Lei Zhang
- Institute of Cancer Research and Basic Medical Sciences of Chinese Academy of Sciences, China; Department of Radiology, Zhejiang Cancer Hospital, Hangzhou, Zhejiang, China; Department of Radiology, Cancer Hospital of the University of Chinese Academy of Sciences, China
| | - Zhimin Ye
- Institute of Cancer Research and Basic Medical Sciences of Chinese Academy of Sciences, China; Department of Radiotherapy, Zhejiang Cancer Hospital, Hangzhou, Zhejiang, China; Department of Radiology, Cancer Hospital of the University of Chinese Academy of Sciences, China
| | - Lei Ruan
- Institute of Cancer Research and Basic Medical Sciences of Chinese Academy of Sciences, China; Department of Radiology, Zhejiang Cancer Hospital, Hangzhou, Zhejiang, China; Department of Radiology, Cancer Hospital of the University of Chinese Academy of Sciences, China
| | - Mingxiang Jiang
- Institute of Cancer Research and Basic Medical Sciences of Chinese Academy of Sciences, China; Department of Radiology, Zhejiang Cancer Hospital, Hangzhou, Zhejiang, China; Department of Radiology, Cancer Hospital of the University of Chinese Academy of Sciences, China.
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Kearney M, Coffey M, Leong A. A review of Image Guided Radiation Therapy in head and neck cancer from 2009-201 - Best Practice Recommendations for RTTs in the Clinic. Tech Innov Patient Support Radiat Oncol 2020; 14:43-50. [PMID: 32566769 PMCID: PMC7296359 DOI: 10.1016/j.tipsro.2020.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/17/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023] Open
Abstract
Radiation therapy (RT) is beneficial in Head and Neck Cancer (HNC) in both the definitive and adjuvant setting. Highly complex and conformal planning techniques are becoming standard practice in delivering increased doses in HNC. A sharp falloff in dose outside the high dose area is characteristic of highly complex techniques and geometric uncertainties must be minimised to prevent under dosage of the target volume and possible over dosage of surrounding critical structures. CTV-PTV margins are employed to account for geometric uncertainties such as set up errors and both interfraction and intrafraction motion. Robust immobilisation and Image Guided Radiation Therapy (IGRT) is also essential in this group of patients to minimise discrepancies in patient position during the treatment course. IGRT has evolved with increased 2-Dimensional (2D) and 3-Dimensional (3D) IGRT modalities available for geometric verification. 2D and 3D IGRT modalities are both beneficial in geometric verification while 3D imaging is a valuable tool in assessing volumetric changes that may have dosimetric consequences for this group of patients. IGRT if executed effectively and efficiently provides clinicians with confidence to reduce CTV-PTV margins thus limiting treatment related toxicities in patients. Accumulated exposure dose from IGRT vary considerably and may be incorporated into the treatment plan to avoid excess dose. However, there are considerable variations in the application of IGRT in RT practice. This paper aims to summarise the advances in IGRT in HNC treatment and provide clinics with recommendations for an IGRT strategy for HNC in the clinic.
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Affiliation(s)
- Maeve Kearney
- Applied Radiation Therapy Trinity, Discipline of Radiation Therapy, Trinity College, Dublin 2, Ireland
| | - Mary Coffey
- Applied Radiation Therapy Trinity, Discipline of Radiation Therapy, Trinity College, Dublin 2, Ireland
| | - Aidan Leong
- Department of Radiation Therapy, University of Otago, Wellington, New Zealand.,Bowen Icon Cancer Centre, Wellington, New Zealand
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Morgan HE, Sher DJ. Adaptive radiotherapy for head and neck cancer. CANCERS OF THE HEAD & NECK 2020; 5:1. [PMID: 31938572 PMCID: PMC6953291 DOI: 10.1186/s41199-019-0046-z] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/11/2019] [Indexed: 12/14/2022]
Abstract
Background Although there have been dramatic improvements in radiotherapy for head and neck squamous cell carcinoma (HNSCC), including robust intensity modulation and daily image guidance, these advances are not able to account for inherent structural and spatial changes that may occur during treatment. Many sources have reported volume reductions in the primary target, nodal volumes, and parotid glands over treatment, which may result in unintended dosimetric changes affecting the side effect profile and even efficacy of the treatment. Adaptive radiotherapy (ART) is an exciting treatment paradigm that has been developed to directly adjust for these changes. Main body Adaptive radiotherapy may be divided into two categories: anatomy-adapted (A-ART) and response-adapted ART (R-ART). Anatomy-adapted ART is the process of re-planning patients based on structural and spatial changes occurring over treatment, with the intent of reducing overdosage of sensitive structures such as the parotids, improving dose homogeneity, and preserving coverage of the target. In contrast, response-adapted ART is the process of re-planning patients based on response to treatment, such that the target and/or dose changes as a function of interim imaging during treatment, with the intent of dose escalating persistent disease and/or de-escalating surrounding normal tissue. The impact of R-ART on local control and toxicity outcomes is actively being investigated in several currently accruing trials. Conclusions Anatomy-adapted ART is a promising modality to improve rates of xerostomia and coverage in individuals who experience significant volumetric changes during radiation, while R-ART is currently being studied to assess its utility in either dose escalation of radioresistant disease, or de-intensification of surrounding normal tissue following treatment response. In this paper, we will review the existing literature and recent advances regarding A-ART and R-ART.
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Affiliation(s)
- Howard E Morgan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2280 Inwood Rd, Dallas, TX 75390 USA
| | - David J Sher
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2280 Inwood Rd, Dallas, TX 75390 USA
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