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Experimental results show that hosing of a long particle bunch in plasma can be induced by wakefields driven by a short, misaligned preceding bunch. Hosing develops in the plane of misalignment, self-modulation in the perpendicular plane, at frequencies close to the plasma electron frequency, and are reproducible. Development of hosing depends on misalignment direction, its growth on misalignment extent and on proton bunch charge. Results have the main characteristics of a theoretical model, are relevant to other plasma-based accelerators and represent the first characterization of hosing.
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A long, narrow, relativistic charged particle bunch propagating in plasma is subject to the self-modulation (SM) instability. We show that SM of a proton bunch can be seeded by the wakefields driven by a preceding electron bunch. SM timing reproducibility and control are at the level of a small fraction of the modulation period. With this seeding method, we independently control the amplitude of the seed wakefields with the charge of the electron bunch and the growth rate of SM with the charge of the proton bunch. Seeding leads to larger growth of the wakefields than in the instability case.
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PURPOSE: To determine outcomes and toxicities after reirradiation for locally recurrent nasopharyngeal carcinoma (rNPC) and to apply a prognostic index in a non-endemic region. METHODS: We retrospectively reported progression-free survival (PFS), overall survival (OS), and treatment-related toxicities in patients treated with curative intent for locally rNPC. We applied the prognostic model for OS and grade 5 radiotherapy (RT)-related toxicities published by Li et al. and evaluated its prognostic accuracy by receiver operating characteristic (ROC) curve analysis. RESULTS: Between 2005 and 2018, 33 patients were treated for rNPC in our institution. Median follow-up was 60 months. The mean time to local recurrence was 75 months. Six (18%) patients had a persistent grade 3 toxicity from a previous RT course. The median re-RT dose was 66â¯Gy. After re-RT, 13 patients had local failure and 3 patients had metastatic recurrence. Median PFS was 18 months with a 5-year PFS rate of 29%. Median OS was 35 months with a 5-year OS rate of 37%. Grade 3 or higher toxicities rate was 74%. There were 21% grade 5 toxicities. The median time to a grade 5 toxicity was less than 6 months following re-RT. The prognostic nomogram was not predictive for OS or grade 5 toxicities. CONCLUSION: Reirradiation of rNPC is an effective treatment but is associated with a high rate of life-threatening toxicity. Stratification of patients based on their risk of developing severe toxicity is needed to select patients who will most likely benefit from re-RT.
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Carcinoma Nasofaríngeo/radioterapia , Neoplasias Nasofaríngeas/radioterapia , Recurrencia Local de Neoplasia/radioterapia , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Reirradiación/efectos adversos , Reirradiación/métodos , Estudios Retrospectivos , Resultado del Tratamiento , Adulto JovenRESUMEN
We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude [≥(4.1±0.4) MV/m], the phase of the modulation along the bunch is reproducible from event to event, with 3%-7% (of 2π) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated.
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We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies in the modulation power spectrum. Results are consistent with changes in wakefields' phase velocity due to plasma density gradients adding to the slow wakefields' phase velocity during self-modulation growth predicted by linear theory.
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Background: Concomitant chemotherapy (CT)-radiotherapy (RT) is a standard of care in locally advanced nasopharyngeal carcinoma (NPC) and a role for induction CT is not established. Methods: Patients with locally advanced NPC, WHO type 2 or 3, were randomized to induction TPF plus concomitant cisplatin-RT or concomitant cisplatin-RT alone. The TPF regimen consisted of three cycles of Docetaxel 75 mg/m2 day 1; cisplatin 75 mg/m2 day 1; 5FU 750 mg/m2/day days 1-5. RT consisted of 70 Gy in 7 weeks plus concomitant cisplatin 40 mg/m2 weekly. Results: A total of 83 patients were included in the study. Demographics and tumour characteristics were well balanced between both arms. Most of the patients (95%) in the TPF arm received three cycles of induction CT. The rate of grade 3-4 toxicity and the compliance (NCI-CTCAE v3) during cisplatin-RT were not different between both arms. With a median follow-up of 43.1 months, the 3-year PFS rate was 73.9% in the TPF arm versus 57.2% in the reference arm [hazard ratio (HR) = 0.44; 95% confidence interval (CI): 0.20-0.97, P = 0.042]. Similarly the 3 years overall survival rate was 86.3% in the TPF arm versus 68.9% in the reference arm (HR = 0.40; 95% CI: 0.15-1.04, P = 0.05). Conclusion: In conclusion, several important aspects can be emphasized: the compliance to induction TPF was good and TPF did not compromise the tolerance of the concomitant RT-cisplatin phase. The improved PFS and overall survival rates needs to be confirmed by further trials.
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Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Quimioterapia de Inducción/métodos , Carcinoma Nasofaríngeo/tratamiento farmacológico , Neoplasias Nasofaríngeas/tratamiento farmacológico , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Quimioradioterapia/métodos , Cisplatino/administración & dosificación , Cisplatino/efectos adversos , Docetaxel/administración & dosificación , Docetaxel/efectos adversos , Femenino , Fluorouracilo/administración & dosificación , Fluorouracilo/efectos adversos , Humanos , Quimioterapia de Inducción/efectos adversos , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Carcinoma Nasofaríngeo/mortalidad , Carcinoma Nasofaríngeo/radioterapia , Neoplasias Nasofaríngeas/mortalidad , Neoplasias Nasofaríngeas/radioterapiaRESUMEN
INTRODUCTION: The introduction of new treatments in metastatic castration resistant prostate cancer (mCRPC) requires a close follow-up to detect a progression and then to adapt the treatment. In that context, a national survey was proposed to a group of experts and the aim was to identify the modalities of surveillance in different clinical situations. METHODS: A questionnaire was sent to 1464 urologists, medical oncologists and radiotherapists, about a clinical case; it was about a patient presenting a prostate cancer, evolving from a biologic progression after radical prostatectomy to a situation of metastasis resistant to the castration. The questionnaire contained ten questions about reasons of changing treatment because of progression, and about modalities of the follow-up. RESULTS: A total of 318 questionnaires were analyzed (response rate of 22%). The results showed comparable practices between the different types of specialists, even if a more frequent rhythm of surveillance was reported by medical oncologists and radiotherapists. At progression after radical prostatectomy, a clinical and biological surveillance was generally realized every 3 or 6 months, and imaging exams were done on demand. Then, as the cancer progresses, the surveillance became systematic and more and more close, with imaging done every 3 months or on demand. While the definition of progression was essentially based on PSA testing at the beginning of the castration resistance, it then combines different clinical, biological and radiological criteria. CONCLUSIONS: There are few recommendations available about follow-up of patients with a mCRPC. In that survey, the oncologists and urologists reported a more intensive rhythm of surveillance as the prostate cancer progresses. LEVEL OF EVIDENCE: 4.
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Neoplasias de la Próstata Resistentes a la Castración/terapia , Anciano , Progresión de la Enfermedad , Francia , Encuestas de Atención de la Salud , Humanos , Masculino , Prostatectomía , Neoplasias de la Próstata/cirugíaRESUMEN
Due to the generally poor prognosis of head and neck squamous cell carcinoma (HNSCC), treatment has been intensified, these last decades, leading to an increase of serious side effects. High-risk human papillomavirus (HR-HPV) infection has been recently etiologically linked to a subset of oropharyngeal squamous cell carcinoma (OPSCC), which is on the increase. These tumors are different, at the clinical and molecular level, when compared to tumors caused by traditional risk factors. Additionally, their prognosis is much more favorable which has led the medical community to consider new treatment strategies. Indeed, it is possible that less intensive treatment regimens could achieve similar efficacy with less toxicity and improved quality of life. Several clinical trials, investigating different ways to de-escalate treatment, are currently ongoing. In this article, we review these main approaches, discuss the rationale behind them and the issues raised by treatment de-escalation in HPV-positive OPSCC.
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Neoplasias Orofaríngeas/etiología , Neoplasias Orofaríngeas/terapia , Infecciones por Papillomavirus/complicaciones , Vacunas contra el Cáncer/uso terapéutico , Ensayos Clínicos como Asunto , Terapia Combinada , Humanos , Resultado del TratamientoRESUMEN
PURPOSE: Squamous cell carcinoma of larynx with subglottic extension (sSCC) is a rare location described to carry a poor prognosis. The aim of this study was to analyze outcomes and feasibility of larynx preservation in sSCC patients. PATIENTS AND METHODS: Between 1996 and 2012, 197 patients with sSCC were treated at our institution and included in the analysis. Stage III-IV tumors accounted for 76%. Patients received surgery (62%), radiotherapy (RT) (18%), or induction chemotherapy (CT) (20%) as front-line therapy. RESULTS: The 5-year actuarial overall survival (OS), locoregional control (LRC), and distant control rate were 59% (95% CI 51-68), 83% (95% CI 77-89), and 88% (95% CI 83-93), respectively, with a median follow-up of 54.4 months. There was no difference in OS and LRC according to front-line treatments or between primary subglottic cancer and glottosupraglottic cancers with subglottic extension. In the multivariate analysis, age > 60 years and positive N stage were the only predictors for OS (HR 2, 95% CI 1.2-3.6; HR1.9, 95% CI 1-3.5, respectively). A lower LRC was observed for T3 patients receiving a larynx preservation protocol as compared with those receiving a front-line surgery (HR 14.1, 95% CI 2.5-136.7; p = 0.02); however, no difference of ultimate LRC was observed according to the first therapy when including T3 patients who underwent salvage laryngectomy (p = 0.6). In patients receiving a larynx preservation protocol, the 5-year larynx-preservation rate was 55% (95% CI 43-68), with 36% in T3 patients. The 5-year larynx preservation rate was 81% (95% CI 65-96) and 35% (95% CI 20-51) for patients who received RT or induction CT as a front-line treatment, respectively. CONCLUSION: Outcomes of sSCC are comparable with other laryngeal cancers when managed with modern therapeutic options. Larynx-preservation protocols could be a suitable option in T1-T2 (RT or chemo-RT) and selected T3 sSCC patients (induction CT).
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Carcinoma de Células Escamosas/radioterapia , Glotis/efectos de la radiación , Neoplasias Laríngeas/radioterapia , Tratamientos Conservadores del Órgano/estadística & datos numéricos , Órganos en Riesgo/efectos de la radiación , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/mortalidad , Femenino , Francia/epidemiología , Humanos , Neoplasias Laríngeas/mortalidad , Masculino , Persona de Mediana Edad , Tratamientos Conservadores del Órgano/métodos , Prevalencia , Estudios Retrospectivos , Tasa de Supervivencia , Resultado del TratamientoRESUMEN
Head and neck carcinomas are initially metastatic in about 15% of cases. Radiotherapy is a cornerstone in the multimodal strategy at the locoregional phase. In patients with head and neck cancer, often heavily pretreated and with comorbidities, who relapse locoregionally or at distant sites, radiotherapy has also become increasingly important at the metastatic phase. Data on the optimal sequence of systemic treatments and metastasis-directed treatments including stereotactic irradiation are still lacking. Several randomized head and neck trials have been initiated that should provide important answers, including one recent GORTEC trial.
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Carcinoma de Células Escamosas , Neoplasias de Cabeza y Cuello , Radiocirugia , Humanos , Recurrencia Local de Neoplasia/radioterapia , Neoplasias de Cabeza y Cuello/radioterapia , Carcinoma de Células Escamosas/radioterapiaRESUMEN
PURPOSE: The increased risk of second cancer after prostate radiotherapy is a debated clinical concern. The objective of the study was to assess the risk of occurrence of second cancers after prostate radiation therapy based on the analysis the literature, and to identify potential factors explaining the discrepancies in results between studies. MATERIALS AND METHODS: A review of the literature was carried out, comparing the occurrence of second cancers in patients all presenting with prostate cancer, treated or not by radiation. RESULTS: This review included 30 studies reporting the occurrence of second cancers in 2,112,000 patients treated or monitored for localized prostate cancer, including 1,111,000 by external radiation therapy and 103,000 by brachytherapy. Regarding external radiation therapy, the average follow-up was 7.3years. The majority of studies (80%) involving external radiation therapy, compared to no external radiation therapy, showed an increased risk of second cancers with a hazard ratio ranging from 1.13 to 4.9, depending on the duration of the follow-up. The median time to the occurrence of these second cancers after external radiotherapy ranged from 4 to 6years. An increased risk of second rectal and bladder cancer was observed in 52% and 85% of the studies, respectively. Considering a censoring period of more than 10 years after irradiation, 57% and 100% of the studies found an increased risk of rectal and bladder cancer, without any impact in overall survival. Studies of brachytherapy did not show an increased risk of second cancer. However, these comparative studies, most often old and retrospective, had many methodological biases. CONCLUSION: Despite numerous methodological biases, prostate external radiation therapy appears associated with a moderate increase in the risk of second pelvic cancer, in particular bladder cancer, without impacting survival. Brachytherapy does not increase the risk of a second cancer.
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Braquiterapia , Neoplasias Inducidas por Radiación , Neoplasias Primarias Secundarias , Neoplasias de la Próstata , Humanos , Masculino , Neoplasias de la Próstata/radioterapia , Neoplasias Primarias Secundarias/etiología , Neoplasias Primarias Secundarias/epidemiología , Neoplasias Inducidas por Radiación/etiología , Neoplasias Inducidas por Radiación/epidemiología , Braquiterapia/efectos adversos , Braquiterapia/métodos , Neoplasias de la Vejiga Urinaria/radioterapia , Neoplasias de la Vejiga Urinaria/etiología , Neoplasias del Recto/radioterapia , Neoplasias del Recto/etiologíaRESUMEN
Purpose: The optimal management of locally recurrent prostate cancer after definitive irradiation is still unclear but local salvage treatments are gaining interest. A retrospective, single-institution analysis of clinical outcomes and treatment-related toxicity after salvage I-125 low-dose-rate (LDR) brachytherapy (BT) for locally-recurrent prostate cancer was conducted in a Comprehensive Cancer Center. Patients and methods: A total of 94 patients treated with salvage LDR-BT between 2006 and 2021 were included. The target volume was either the whole-gland +/- a boost on the GTV, the hemigland, or only the GTV. The prescribed dose ranged from 90 to 145 Gy. Toxicity was graded by Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Results: Median follow-up was 34 months. Initial radiotherapy was external beam radiotherapy in 73 patients (78 %) with a median dose of 76 Gy and I-125 BT in 21 patients (22 %) with a prescribed dose of 145 Gy. Median PSA at salvage was 3.75 ng/ml with a median interval between first and salvage irradiation of 9.4 years. Salvage brachytherapy was associated with androgen deprivation therapy for 32 % of the patients. Only 4 % of the patients were castrate-resistant. Failure free survival was 82 % at 2 years and 66 % at 3 years. The only factors associated with failure-free survival on multivariate analysis were hormonosensitivity at relapse and European Association of Urology (EAU) prognostic group. Late grade 3 urinary and rectal toxicities occurred in 12 % and 1 % of the patients respectively.No significant difference in toxicity or efficacy was observed between the three implant volume groups. Conclusion: The efficacy and toxicity results are consistent with those in the LDR group of the MASTER meta-analysis. Salvage BT confirms to be an effective and safe option for locally recurrent prostate cancer. A focal approach could be interesting to reduce late severe toxicities, especially urinary.
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BACKGROUND: Prostate cancer in younger men is rare but not exceptional. Radiotherapy is a cornerstone of prostate cancer treatment and yet, its impact on fertility is scarcely reported in literature. Given the radiosensitivity of testicular tissue, this study aimed to determine the testicular dose using modern radiotherapy techniques for definitive prostate irradiation. METHODS: One hundred radiotherapy plans were reviewed. Testicles were contoured retrospectively without dosimetric optimization on testicles. RESULTS: The median testicular dose was 0.58 Gy: 0.18 Gy in stereotactic plans, 0.62 Gy in Volumetric Modulated Arc Therapy plans and 1.50 Gy in Tomotherapy plans (p < 0.001). Pelvic nodal irradiation increased the median testicular dose to 1.18 Gy versus 0.26 Gy without nodal irradiation (p < 0.001). Weight and BMI were inversely associated with testicular dose (p < 0.005). 65% of patients reached the theoretical dose threshold for transient azoospermia, and 10% received more than 2 Gy, likely causing definitive azoospermia. CONCLUSION: Despite being probably lower than doses from older techniques, the testicular dose delivered with modern prostate radiotherapy is not negligible and is often underestimated because the contribution of daily repositioning imaging is not taken into account and most Treatment Planning Systems underestimate the out of field dose. Radiation oncologists should consider the impact on fertility and gonadal endocrine function, counseling men on sperm preservation if they wish to maintain fertility. TRIAL REGISTRATION: retrospectively registered.
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Neoplasias de la Próstata , Dosificación Radioterapéutica , Planificación de la Radioterapia Asistida por Computador , Radioterapia de Intensidad Modulada , Testículo , Humanos , Masculino , Neoplasias de la Próstata/radioterapia , Estudios Retrospectivos , Testículo/efectos de la radiación , Persona de Mediana Edad , Radioterapia de Intensidad Modulada/efectos adversos , Radioterapia de Intensidad Modulada/métodos , Planificación de la Radioterapia Asistida por Computador/métodos , Órganos en Riesgo/efectos de la radiación , Anciano , Adulto , Traumatismos por Radiación/etiología , Fertilidad/efectos de la radiaciónRESUMEN
Metastatic bladder and renal cancers account respectively for 2.1% and 1.8% of cancer deaths worldwide. The advent of immune checkpoint inhibitors has revolutionized the management of metastatic disease, by demonstrating considerable improvements in overall survival. However, despite initial sensitivity to immune checkpoint inhibitors for most patients, both bladder and renal cancer are associated with short progression-free survival and overall survival, raising the need for further strategies to improve their efficacy. Combining systemic therapies with local approaches is a longstanding concept in urological oncology, in clinical settings including both oligometastatic and polymetastatic disease. Radiation therapy has been increasingly studied with either cytoreductive, consolidative, ablative or immune boosting purposes, but the long-term impact of this strategy remains unclear. This review intends to address the impact of radiation therapy with either curative or palliative intent, for synchronous de novo metastatic bladder and renal cancers.
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Neoplasias Renales , Vejiga Urinaria , Humanos , Inhibidores de Puntos de Control Inmunológico , Neoplasias Renales/radioterapia , Supervivencia sin ProgresiónRESUMEN
In this article, we propose a consensus delineation of postoperative clinical target volumes for the primary tumour in maxillary sinus and nasal cavity cancers. These guidelines are developed based on radioanatomy and the natural history of those cancers. They require the fusion of the planning CT with preoperative imaging for accurate positioning of the initial GTV and the combined use of the geometric and anatomical concepts for the delineation of clinical target volume for the primary tumour. This article does not discuss the indications of external radiotherapy (nor concurrent systemic treatment) but focuses on target volumes when there is an indication for radiotherapy.
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Neoplasias de la Boca , Neoplasias de los Senos Paranasales , Humanos , Seno Maxilar/diagnóstico por imagen , Seno Maxilar/cirugía , Seno Maxilar/patología , Cavidad Nasal/diagnóstico por imagen , Planificación de la Radioterapia Asistida por Computador/métodos , Neoplasias de la Boca/patologíaRESUMEN
We show in experiments that a long, underdense, relativistic proton bunch propagating in plasma undergoes the oblique instability, which we observe as filamentation. We determine a threshold value for the ratio between the bunch transverse size and plasma skin depth for the instability to occur. At the threshold, the outcome of the experiment alternates between filamentation and self-modulation instability (evidenced by longitudinal modulation into microbunches). Time-resolved images of the bunch density distribution reveal that filamentation grows to an observable level late along the bunch, confirming the spatiotemporal nature of the instability. We provide a rough estimate of the amplitude of the magnetic field generated in the plasma by the instability and show that the associated magnetic energy increases with plasma density.
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Advancements in genotyping are rapidly decreasing marker costs and increasing marker density. This opens new possibilities for mapping quantitative trait loci (QTL), in particular by combining linkage disequilibrium information and linkage analysis (LDLA). In this study, we compared different approaches to detect QTL for four traits of agronomical importance in two large multi-parental datasets of maize (Zea mays L.) of 895 and 928 testcross progenies composed of 7 and 21 biparental families, respectively, and genotyped with 491 markers. We compared to traditional linkage-based methods two LDLA models relying on the dense genotyping of parental lines with 17,728 SNP: one based on a clustering approach of parental line segments into ancestral alleles and one based on single marker information. The two LDLA models generally identified more QTL (60 and 52 QTL in total) than classical linkage models (49 and 44 QTL in total). However, they performed inconsistently over datasets and traits suggesting that a compromise must be found between the reduction of allele number for increasing statistical power and the adequacy of the model to potentially complex allelic variation. For some QTL, the model exclusively based on linkage analysis, which assumed that each parental line carried a different QTL allele, was able to capture remaining variation not explained by LDLA models. These complementarities between models clearly suggest that the different QTL mapping approaches must be considered to capture the different levels of allelic variation at QTL involved in complex traits.
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Mapeo Cromosómico , Haplotipos/genética , Desequilibrio de Ligamiento/genética , Modelos Genéticos , Polimorfismo Genético , Sitios de Carácter Cuantitativo/genética , Zea mays/genética , Alelos , Análisis por Conglomerados , Cruzamientos Genéticos , Sitios Genéticos/genética , Genoma de Planta/genética , Patrón de Herencia/genéticaRESUMEN
Stereotactic Body Radiation Therapy (SBRT) is a standard of care for many localizations but the question of the optimal fractionation remains a matter of concern. If single fraction sessions are routinely used for intracranial targets, their utilization for mobile extracranial lesions is a source of debate and apprehension. Single session treatments improve patient comfort, provide a medico-economic benefit, and have proven useful in the context of the SARS-CoV 2 pandemic. However, both technical and radiobiological uncertainties remain. Experience from intracranial radiosurgery has shown that the size of the target, its proximity to organs at risk, tumor histology, and the volume of normal tissue irradiated are all determining factors in the choice of fractionation. The literature on the use of single fraction for extracranial sites is still scarce. Only primary and secondary pulmonary tumors have been evaluated in prospective randomized trials, allowing the integration of these fractionation schemes in daily practice, for highly selected cases and in trained teams. The level of evidence for the other organs is mainly based on dose escalation or retrospective trials and calls for caution, with further studies being needed before routine use in clinical practice.
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The incidence of primary renal cancer is increasing, particularly in elderly patients who may have comorbidities and/or a surgical contraindications. Stereotactic body radiotherapy has primarily been evaluated retrospectively to date. The most commonly used dose schedules are 40Gy in five fractions, 42Gy in three fractions, and 26Gy in one fraction. The results in terms of local control and toxicity are very encouraging. The advantages of stereotactic body radiotherapy compared to thermal ablative treatments are its non-invasive nature, absence of general anesthesia, ability to treat larger lesions, and those close to the renal hilum. Prospective evaluations are still necessary.