International Guideline on Dose Prioritization and Acceptance Criteria in Radiation Therapy Planning for Nasopharyngeal Carcinoma

Purpose: The treatment of nasopharyngeal carcinoma requires high radiation doses. The balance of the risks of local recurrence owing to inadequate tumor coverage versus the potential damage to the adjacent organs at risk (OARs) is of critical importance. With advancements in technology, high target conformality is possible. Nonetheless, to achieve the best possible dose distribution, optimal setting of dose targets and dose prioritization for tumor volumes and various OARs is fundamental. Radiation doses should always be guided by the As Low As Reasonably Practicable principle. There are marked variations in practice. This study aimed to develop a guideline to serve as a global practical reference. Methods and Materials: A literature search on dose tolerances and normal-tissue complications after treatment for nasopharyngeal carcinoma was conducted. In addition, published guidelines and protocols on dose prioritization and constraints were reviewed. A text document and preliminary set of variants was circulated to a panel of international experts with publications or extensive experience in the field. An anonymized voting process was conducted to rank the proposed variants. A summary of the initial voting and different opinions expressed by members were then recirculated to the whole panel for review and reconsideration. Based on the comments of the panel, a refined second proposal was recirculated to the same panel. The current guideline was based on majority voting after repeated iteration for final agreement. Results: Variation in opinion among international experts was repeatedly iterated to develop a guideline describing appropriate dose prioritization and constraints. The percentage of final agreement on the recommended parameters and alternative views is shown. The rationale for the recommendations and the limitations of current evidence are discussed. Conclusions: Through this comprehensive review of available evidence and interactive exchange of vast experience by international experts, a guideline was developed to provide a practical reference for setting dose prioritization and acceptance criteria for tumor volumes and OARs. The final decision on the treatment prescription should be based on the individual clinical situation and the patient's acceptance of optimal balance of risk. (C) 2019 Elsevier Inc. All rights reserved

International Recommendations on Reirradiation by Intensity Modulated Radiation Therapy for Locally Recurrent Nasopharyngeal Carcinoma

Purpose: Reirradiation for locally recurrent nasopharyngeal carcinoma (NPC) is challenging because prior radiation dose delivered in the first course is often close to the tolerance limit of surrounding normal structures. A delicate balance between achieving local salvage and minimizing treatment toxicities is needed. However, high-level evidence is lacking because available reports are mostly retrospective studies on small series of patients. Pragmatic consensus guidelines, based on an extensive literature search and the pooling of opinions by leading specialists, will provide a useful reference to assist decision-making for these difficult decisions. Methods and Materials: A thorough review of available literature on recurrent NPC was conducted. A set of questions and preliminary draft guideline was circulated to a panel of international specialists with extensive experience in this field for voting on controversial areas and comments. A refined second proposal, based on a summary of the initial voting and different opinions expressed, was recirculated to the whole panel for review and reconsideration. The current guideline was based on majority voting after repeated iteration for final agreement. Results: The initial round of questions showed variations in clinical practice even among the specialists, reflecting the lack of high-quality supporting data and the difficulties in formulating clinical decisions. Through exchange of comments and iterative revisions, recommendations with high-to-moderate agreement were formulated on general treatment strategies and details of reirradiation (including patient selection, targets contouring, dose prescription, and constraints). Conclusion: This paper provides useful reference on radical salvage treatment strategies for recurrent NPC and optimization of reirradiation through review of published evidence and consensus building. However, the final decision by the attending clinician must include full consideration of an individual patient's condition, understanding of the delicate balance between risk and benefits, and acceptance of risk of complications. (C) 2021 Elsevier Inc. All rights reserved

A multi-centric evaluation of self-learning GAN based pseudo-CT generation software for low field pelvic magnetic resonance imaging

Purpose/objectivesAn artificial intelligence-based pseudo-CT from low-field MR images is proposed and clinically evaluated to unlock the full potential of MRI-guided adaptive radiotherapy for pelvic cancer care.Materials and methodIn collaboration with TheraPanacea (TheraPanacea, Paris, France) a pseudo-CT AI-model was generated using end-to-end ensembled self-supervised GANs endowed with cycle consistency using data from 350 pairs of weakly aligned data of pelvis planning CTs and TrueFisp-(0.35T)MRIs. The image accuracy of the generated pCT were evaluated using a retrospective cohort involving 20 test cases coming from eight different institutions (US: 2, EU: 5, AS: 1) and different CT vendors. Reconstruction performance was assessed using the organs at risk used for treatment. Concerning the dosimetric evaluation, twenty-nine prostate cancer patients treated on the low field MR-Linac (ViewRay) at Montpellier Cancer Institute were selected. Planning CTs were non-rigidly registered to the MRIs for each patient. Treatment plans were optimized on the planning CT with a clinical TPS fulfilling all clinical criteria and recalculated on the warped CT (wCT) and the pCT. Three different algorithms were used: AAA, AcurosXB and MonteCarlo. Dose distributions were compared using the global gamma passing rates and dose metrics.ResultsThe observed average scaled (between maximum and minimum HU values of the CT) difference between the pCT and the planning CT was 33.20 with significant discrepancies across organs. Femoral heads were the most reliably reconstructed (4.51 and 4.77) while anal canal and rectum were the less precise ones (63.08 and 53.13). Mean gamma passing rates for 1%1mm, 2%/2mm, and 3%/3mm tolerance criteria and 10% threshold were greater than 96%, 99% and 99%, respectively, regardless the algorithm used. Dose metrics analysis showed a good agreement between the pCT and the wCT. The mean relative difference were within 1% for the target volumes (CTV and PTV) and 2% for the OARs.ConclusionThis study demonstrated the feasibility of generating clinically acceptable an artificial intelligence-based pseudo CT for low field MR in pelvis with consistent image accuracy and dosimetric results

T4N0M0 nasopharyngeal carcinoma patients: do they have a distinct tumor biology?

Objectives: To investigate the clinical manifestations and treatment outcomes of non-metastatic T4N0 nasopharyngeal cancer patients, and to compare them with other stage IVA subgroups of patients. Patients and Methods: A retrospective analysis of 775 non-metastatic nasopharyngeal cancer patients, treated in four radiotherapy centers between 1990 and 2005, was undertaken. Among 197 stage IVA patients, 90 (11.6%) patients were staged as T4N0, 32 (4.1%) as T4N1, and 75 (9.7%) as T4N2. T4N0 patients constituted 40.8% of all T4 cases (median age 53 years; range 15 to 76 years). Cranial nerve involvement was detected in 59 (65.5%) of these cases. Results: The median follow-up period was 38 months. There were only nine (10%) patients younger than 30 years of age with T4N0 tumors, for patients with diseases other than T4N0, 27.1% of the patients were under 30. Survival rates for five-year loco-regional progression free survival, distant failure free survival, and disease specific survival were 65.9%, 94%, and 71.4%, respectively. Distant failure free survival of T4N0 patients was more probable than for stage T4N1 (p=0.06) and T4N2 (p=0.008) patients. Conclusion: Non-metastatic T4N0 tumors have some distinct features, including a unimodal age distribution and a better distant failure free survival than the other subgroups of stage IVA. Therefore, it may be better to include T4N0 patients in stage III instead of stage IVA.Amaç: Tümörleri T4N0 olarak evrelenen metastatik olmayan nazofarenks kanserli hastaların tedavi ve klinik özellikleri incelendi; elde edilen sonuçlar evre IVA’nın diğer alt gruplarında yer alan hastaların sonuçları ile karşılaştırıldı. Hastalar ve Yöntemler: Dört radyoterapi merkezinde 1990 ve 2005 yılları arasında tedavi edilmiş metastatik olmayan toplam 775 nazofarenks kanseri tanılı hasta geriye dönük incelendi. Bu hastalardan evre IVA olan 197’sinin dağılımı; 90’ı (%11.6) T4N0, 32’si (%4.1) T4N1 ve 75’i (%9.7) T4N2 şeklindeydi. T4N0 hastalar tüm T4 hastalarının %40.8’ini (ortanca yaş 53 yıl; dağılım 15-76 yıl) oluşturmaktaydı. Kraniyal sinir tutulumu bu hastalardan 59’unda (%65.5) izlendi. Bulgular: Ortanca takip süresi 38 ay idi. T4N0 hastalardan sadece dokuzu (%10) 30 yaş altı iken diğer T4N0 alt gruplarındaki hastaların ise %27.1’i 30 yaş altında idi. Beş yıllık lokal bölgesel progresyonsuz sağkalım, uzak metastazsız sağkalım ve hastalıksız sağkalım oranları sırasıyla %65.9, %94 ve %71.4 idi. Uzak metastazsız sağkalım evre T4N0 hastalarda diğer T4N1 (p=0.06) ve T4N2 (p=0.008) evre hastalarından daha iyi idi. Sonuç: Metastatik olmayan T4N0 tümörler, unimodal yaş dağılımları ve daha iyi uzak metastazsız sağkalım sonuçları açısından, diğer evre IVA alt gruplarından farklı özellikler göstermektedir. Bu nedenle bu hastaların evre IVA yerine evre III olarak değerlendirilmesi uygun olabilir

In regards to Sze et al.: Primary tumor volume of nasopharyngeal carcinoma: Prognostic significance for local control (Int J Radiat Oncol Biol Phys 2004;59:21-27) [1] (multiple letters)

Link_to_subscribed_fulltex

Undifferentiated nasopharyngeal carcinoma with isolated central nervous system metastasis

Central nervous system (CNS) metastasis from nasopharyngeal carcinoma is an extremely rare event. Here, we report a case of nasopharyngeal carcinoma with isolated CNS metastases 45 months after the successful treatment of primary tumor