Delphi consensus on stereotactic ablative radiotherapy for oligometastatic and oligoprogressive renal cell carcinoma-a European Society for Radiotherapy and Oncology study endorsed by the European Association of Urology.

The purpose of this European Society for Radiotherapy and Oncology (ESTRO) project, endorsed by the European Association of Urology, is to explore expert opinion on the management of patients with oligometastatic and oligoprogressive renal cell carcinoma by means of stereotactic ablative radiotherapy (SABR) on extracranial metastases, with the aim of developing consensus recommendations for patient selection, treatment doses, and concurrent systemic therapy. A questionnaire on SABR in oligometastatic renal cell carcinoma was prepared by a core group and reviewed by a panel of ten prominent experts in the field. The Delphi consensus methodology was applied, sending three rounds of questionnaires to clinicians identified as key opinion leaders in the field. At the end of the third round, participants were able to find consensus on eight of the 37 questions. Specifically, panellists agreed to apply no restrictions regarding age (25 [100%) of 25) and primary renal cell carcinoma histology (23 [92%] of 25) for SABR candidates, on the upper threshold of three lesions to offer ablative treatment in patients with oligoprogression, and on the concomitant administration of immune checkpoint inhibitor. SABR was indicated as the treatment modality of choice for renal cell carcinoma bone oligometatasis (20 [80%] of 25) and for adrenal oligometastases 22 (88%). No consensus or major agreement was reached regarding the appropriate schedule, but the majority of the poll (54%-58%) retained the every-other-day schedule as the optimal choice for all the investigated sites. The current ESTRO Delphi consensus might provide useful direction for the application of SABR in oligometastatic renal cell carcinoma and highlight the key areas of ongoing debate, perhaps directing future research efforts to close knowledge gaps.

Stereotactic radiosurgery and radiotherapy for brainstem metastases: An international multicenter analysis.

Brainstem metastases (BSM) present a significant neuro-oncological challenge, resulting in profound neurological deficits and poor survival outcomes. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) offer promising therapeutic avenues for BSM despite their precarious location. This international multicenter study investigates the efficacy and safety of SRS and FSRT in 136 patients with 144 BSM treated at nine institutions from 2005 to 2022. The median radiographic and clinical follow-up periods were 6.8 and 9.4 months, respectively. Predominantly, patients with BSM were managed with SRS (69.4%). The median prescription dose and isodose line for SRS were 18 Gy and 65%, respectively, while for FSRT, the median prescription dose was 21 Gy with a median isodose line of 70%. The 12-, 24-, and 36-month local control (LC) rates were 82.9%, 71.4%, and 61.2%, respectively. Corresponding overall survival rates at these time points were 61.1%, 34.7%, and 19.3%. In the multivariable Cox regression analysis for LC, only the minimum biologically effective dose was significantly associated with LC, favoring higher doses for improved control (in Gy, hazard ratio [HR]: 0.86, p < .01). Regarding overall survival, good performance status (Karnofsky performance status, ≥90%; HR: 0.43, p < .01) and prior whole brain radiotherapy (HR: 2.52, p < .01) emerged as associated factors. In 14 BSM (9.7%), treatment-related adverse events were noted, with a total of five (3.4%) radiation necrosis. SRS and FSRT for BSM exhibit efficacy and safety, making them suitable treatment options for affected patients.

Patient vulnerability in stereotactic arrhythmia radioablation (STAR): a preliminary ethical appraisal from the STOPSTORM.eu consortium.

This preliminary ethical appraisal from the STOPSTORM.eu consortium is meant to raise critical points that clinicians administering stereotactic arrhythmia radioablation should consider to meet the highest standards in medical ethics and thus promote quality of life of patients recruited for radiotherapy treatments at a stage in which they experience a significant degree of vulnerability.

Implementing stereotactic arrhythmia radioablation with STOPSTORM.eu consortium support: intermediate results of a prospective Israeli single-institutional trial.

BACKGROUND: Ventricular tachycardia (VT) is a life-threatening arrhythmia originating from the heart's ventricles. Traditional treatments include antiarrhythmic medications, implantable cardioverter-defibrillators (ICDs), and catheter ablation. Stereotactic body radiation therapy (SBRT) targeting the arrhythmogenic focus in the left ventricle-stereotactic arrhythmia radioablation (STAR)-is an emerging treatment and may offer a potential solution for patients with refractory VT. OBJECTIVE: We designed an interventional prospective clinical trial in Israel aligned with the STOPSTORM.eu consortium's benchmarks, recommendations, and directives to assess the safety and efficacy of STAR in patients with refractory VT. METHODS: Our phase I/II single-institutional trial was approved by the Ministry of Health of Israel for 10 patients, initially assessing safety in the first 3 patients. We included patients with ICDs experiencing symptomatic monomorphic VT after an inadequate response to previous therapies. The primary endpoints were treatment-related serious adverse events and a reduction in VT burden as assessed by ICD interrogation. Secondary outcomes included a reduction in antiarrhythmic medications and changes in quality of life. RESULTS: From August 2023 to August 2024, 3 patients underwent STAR treatment. The prescription dose was a single fraction of 25 Gy. Planning target volumes were 47.8, 49.7, and 91.8 cc, and treatment was successfully delivered with no grade 3 or higher adverse events reported. Over a follow-up period of 12 months for the first patient and 8 months for the second one, no VT events were recorded after treatment. The third patient died from progressive heart failure 3 months after treatment. Left ventricular ejection fraction remained stable, and no significant radiation-induced inflammatory changes were noted. CONCLUSION: The initial results of this trial suggest that STAR can reduce VT episodes in patients with refractory VT without severe adverse effects. The study highlights the importance of international collaboration and standardization in pioneering new treatments. Further follow-up and additional patient data will be necessary to confirm these findings and evaluate long-term outcomes, including potential adjustments to antiarrhythmic medication regimens.

Quality requirements for MRI simulation in cranial stereotactic radiotherapy: a guideline from the German Taskforce "Imaging in Stereotactic Radiotherapy".

Accurate Magnetic Resonance Imaging (MRI) simulation is fundamental for high-precision stereotactic radiosurgery and fractionated stereotactic radiotherapy, collectively referred to as stereotactic radiotherapy (SRT), to deliver doses of high biological effectiveness to well-defined cranial targets. Multiple MRI hardware related factors as well as scanner configuration and sequence protocol parameters can affect the imaging accuracy and need to be optimized for the special purpose of radiotherapy treatment planning. MRI simulation for SRT is possible for different organizational environments including patient referral for imaging as well as dedicated MRI simulation in the radiotherapy department but require radiotherapy-optimized MRI protocols and defined quality standards to ensure geometrically accurate images that form an impeccable foundation for treatment planning. For this guideline, an interdisciplinary panel including experts from the working group for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO), the working group for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP), the German Society of Neurosurgery (DGNC), the German Society of Neuroradiology (DGNR) and the German Chapter of the International Society for Magnetic Resonance in Medicine (DS-ISMRM) have defined minimum MRI quality requirements as well as advanced MRI simulation options for cranial SRT.

Dose prescription for stereotactic body radiotherapy: general and organ-specific consensus statement from the DEGRO/DGMP Working Group Stereotactic Radiotherapy and Radiosurgery.

PURPOSE AND OBJECTIVE: To develop expert consensus statements on multiparametric dose prescriptions for stereotactic body radiotherapy (SBRT) aligning with ICRU report 91. These statements serve as a foundational step towards harmonizing current SBRT practices and refining dose prescription and documentation requirements for clinical trial designs. MATERIALS AND METHODS: Based on the results of a literature review by the working group, a two-tier Delphi consensus process was conducted among 24 physicians and physics experts from three European countries. The degree of consensus was predefined for overarching (OA) and organ-specific (OS) statements (≥ 80%, 60-79%, < 60% for high, intermediate, and poor consensus, respectively). Post-first round statements were refined in a live discussion for the second round of the Delphi process. RESULTS: Experts consented on a total of 14 OA and 17 OS statements regarding SBRT of primary and secondary lung, liver, pancreatic, adrenal, and kidney tumors regarding dose prescription, target coverage, and organ at risk dose limitations. Degree of consent was ≥ 80% in 79% and 41% of OA and OS statements, respectively, with higher consensus for lung compared to the upper abdomen. In round 2, the degree of consent was ≥ 80 to 100% for OA and 88% in OS statements. No consensus was reached for dose escalation to liver metastases after chemotherapy (47%) or single-fraction SBRT for kidney primaries (13%). In round 2, no statement had 60-79% consensus. CONCLUSION: In 29 of 31 statements a high consensus was achieved after a two-tier Delphi process and one statement (kidney) was clearly refused. The Delphi process was able to achieve a high degree of consensus for SBRT dose prescription. In summary, clear recommendations for both OA and OS could be defined. This contributes significantly to harmonization of SBRT practice and facilitates dose prescription and reporting in clinical trials investigating SBRT.

Electroanatomical mapping after cardiac radioablation for treatment of incessant electrical storm: a case report from the RAVENTA trial.

BACKGROUND: Electroanatomical mapping (EAM)-guided stereotactic arrhythmia radioablation (STAR) is a novel noninvasive therapy option for patients with monomorphic ventricular tachycardia (VT) refractory to antiarrhythmic drugs and/or urgent catheter ablation (CA). Data on success rates in an emergency situation such as electrical storm (ES) are rare. We present a case of a patient with an initially very poor life expectancy after extensive myocardial infarction with therapy-resistant ES, not amendable for further antiarrhythmic drug therapy, implantable cardioverter-defibrillator implantation, or repeated CA who was introduced to the radiation oncology department for emergency STAR as a bail-out therapy. METHODS: Target volume definition and transfer from EAM to CT were validated and quality assured with a semi-automatic, dedicated visualization tool (CARDIO-RT). Emergency STAR was performed with 25 Gy in the framework of the RAVENTA study. The VT burden gradually decreased after STAR; however, a second VT morphology occurred, which was successfully treated with EAM-guided CA 12 days after STAR. RESULTS: The second EAM-guided CA showed areas of low voltage in the irradiated segments, indicating a precise targeting and early functional response to STAR. The patient remained free of any VT recurrence or any radiation-related toxicities and in good general condition during the recent follow-up of 18 months. CONCLUSION: The case highlights the possible approach, caveats, difficulties, and prognosis of a patient severely affected by therapy-resistant VT in whom CA could not lead to VT suppression. Further studies of putative mechanisms of STAR in the acute and chronic phase of this novel therapy are warranted.

Robotic stereotactic body radiotherapy for localized prostate cancer: final analysis of the German HYPOSTAT trial.

PURPOSE: We report results of the first German prospective multicenter single-arm phase II trial (ARO 2013-06; NCT02635256) of hypofractionated robotic stereotactic body radiotherapy (SBRT) for patients with localized prostate cancer (HYPOSTAT). METHODS: Patients eligible for the HYPOSTAT study had localized prostate cancer (cT1­3 cN0 cM0), Gleason score ≤ 7, prostate-specific antigen (PSA) ≤ 15 ng/ml, prostate volume ≤ 80 cm3, and an International Prostate Symptom Score (IPSS) ≤ 12. Initially, inclusion was limited to patients ≥ 75 years or patients 70-74 years with additional risk factors. The trial protocol was later amended to allow for enrolment of patients aged ≥ 60 years. The treatment consisted of 35 Gy delivered in 5 fractions to the prostate and for intermediate- or high-risk patients, also to the proximal seminal vesicles using the CyberKnife system (Accuray Inc., Sunnyvale, CA, USA). Primary endpoint was the rate of treatment-related gastrointestinal or genitourinary grade ≥ 2 toxicity based on the RTOG scale 12-15 months after treatment. Secondary endpoints were acute toxicity, late toxicity, urinary function, quality of life, and PSA response. RESULTS: From July 2016 through December 2018, 85 eligible patients were enrolled and received treatment, of whom 83 could be evaluated regarding the primary endpoint. Patients mostly had intermediate-risk disease with a median PSA value of 7.97 ng/ml and Gleason score of 7a and 7b in 43.5% and 25.9% of patients, respectively. At the final follow-up 12-15 months after treatment, no patient suffered from treatment-related gastrointestinal or genitourinary grade ≥ 2 toxicity. Acute toxicity was mostly mild, with three grade 3 events, and the cumulative rate of grade ≥ 2 genitourinary toxicity was 8.4% (95% CI 4.1-16.4%). There were no major changes in urinary function or quality of life. The median PSA value dropped to 1.18 ng/ml 12-15 months after treatment. There was one patient who developed distant metastases. CONCLUSION: Robotic SBRT with 35 Gy in 5 fractions was associated with a favorable short-term toxicity profile. Recruitment for the HYPOSTAT­2 trial (ARO-2018­4; NCT03795337), which further analyses the late toxicity of this regimen with a planned sample size of 500 patients, is ongoing.

Radiosurgery for ventricular tachycardia (RAVENTA): interim analysis of a multicenter multiplatform feasibility trial.

BACKGROUND: Single-session cardiac stereotactic radiation therapy (SBRT) has demonstrated promising results for patients with refractory ventricular tachycardia (VT). However, the full safety profile of this novel treatment remains unknown and very limited data from prospective clinical multicenter trials are available. METHODS: The prospective multicenter multiplatform RAVENTA (radiosurgery for ventricular tachycardia) study assesses high-precision image-guided cardiac SBRT with 25 Gy delivered to the VT substrate determined by high-definition endocardial and/or epicardial electrophysiological mapping in patients with refractory VT ineligible for catheter ablation and an implanted cardioverter defibrillator (ICD). Primary endpoint is the feasibility of full-dose application and procedural safety (defined as an incidence of serious [grade ≥ 3] treatment-related complications ≤ 5% within 30 days after therapy). Secondary endpoints comprise VT burden, ICD interventions, treatment-related toxicity, and quality of life. We present the results of a protocol-defined interim analysis. RESULTS: Between 10/2019 and 12/2021, a total of five patients were included at three university medical centers. In all cases, the treatment was carried out without complications. There were no serious potentially treatment-related adverse events and no deterioration of left ventricular ejection fraction upon echocardiography. Three patients had a decrease in VT episodes during follow-up. One patient underwent subsequent catheter ablation for a new VT with different morphology. One patient with local VT recurrence died 6 weeks after treatment in cardiogenic shock. CONCLUSION: The interim analysis of the RAVENTA trial demonstrates early initial feasibility of this new treatment without serious complications within 30 days after treatment in five patients. Recruitment will continue as planned and the study has been expanded to further university medical centers. TRIAL REGISTRATION NUMBER: NCT03867747 (clinicaltrials.gov). Registered March 8, 2019. Study start: October 1, 2019.

Long-term characterization of MRI-morphologic alterations after active motion-compensated liver SBRT: a multi-institutional pooled analysis.

BACKGROUND: Stereotactic body radiotherapy (SBRT) is an effective therapeutic approach in patients with liver metastases. However, long-term changes in hepatic normal tissue have to be taken into account in multimodal treatment regimes. Magnetic-resonance-imaging (MRI) based morphologic liver alterations (MMA) after liver SBRT have been analyzed longitudinally. MATERIAL AND METHODS: 57 patients treated with gantry-based or robotic-based SBRT of 69 treatment volumes of liver metastases, who had long-term follow-up (FU) ≥6 months were included in this retrospective analysis. Post-SBRT MMAs were contoured on each contrast-enhanced-T1-weighted (T1w) MRI-sequence. Morphologic/volumetric data of the liver and MMAs were evaluated longitudinally, including the dependency on treatment-related factors of the planning target volume (PTV) and liver. RESULTS: The median FU time was 1 year [6-48 months]. 66 of 69 treatment volumes developed MMAs (mean 143.8 ± 135.1 ccm at first appearance). 31.8% of MMAs resolved completely during FU. Of the persisting MMAs 82.2%/13.3% decreased/increased in size until last available FU. Morphological characterization of the MMAs at first appearance included 75% hypointense and 25% hyperintense T1w-MRI-based appearances. Hypointense as compared to hyperintense appearance was significantly associated with a higher mean liver dose EQD2α/ß=3 Gy (p = 0.0212) and non-significantly greater MMA size. Variance analysis demonstrated a significant reduction of MMA and total liver volume after SBRT (p < 0.0001). The volume reduction decelerated longitudinally for both MMA (p < 0.0001) and liver size (p = 0.0033). Radiation doses (PTV-BEDα/ß=3 Gy and 10 Gy) were not significantly associated with MMA volume reduction. SBRT of liver metastases with mean liver dose EQD2α/ß=3 Gy > 18 Gy were characterized by greater MMA volumes (p = 0.0826) and steeper MMA reduction gradients during FU than those with EQD2α/ß=3 Gy ≤ 18 Gy (p < 0.0001). CONCLUSION: Radiogenic MMAs either completely resolve or usually decrease in volume with pronounced reduction during short-term FU. This course was independent of the MMA's morphological appearance. Further, increased mean liver dose was associated with greater MMA size and a greater gradient of MMA size reduction during FU.

A retrospective multi-center feasibility study of a new PTV margin estimation approach for moving targets using CyberKnife log files.

PURPOSE: This study investigates a new approach for estimating the planning target volume (PTV) margin for moving tumors treated with robotic stereotactic body radiotherapy (SBRT). METHODS: In this new approach, the covariance of modeling and prediction errors was estimated using error propagation and implemented in the Van Herk formula to form a Modified Van Herk formula (MVHF). To perform a retrospective multi-center analysis, the MVHF was studied using 163 patients treated with different system versions of robotic SBRT (G3 version 6.2.3, VSI version 8.5, and VSI version 9.5) and compared with two established PTV margins estimation methods: The original Van Herk Formula (VHF) and the Uncertainty Estimation Method (UEM). RESULTS: Overall, the PTV margins provided by the three formalisms are similar with 4-5 mm in the lung region and 4 mm in abdomen region to the PTV margins used in clinical. Furthermore, when analyzing individual patients, a difference of up to 1 mm was found between the PTV margin estimations using MVHF and VHF. The corresponding average discrepancies for the superior-inferior (SI) direction ranged between -0.19 mm to 0.38 mm in CK G3 version 6.2.3, -0.36 mm to 0.33 mm in CK VSI version 8.5, and -0.34 mm to 0.40 mm in CK VSI version 9.5. CONCLUSIONS: It was found that for the lower left lung, upper left lung, lower right lung, upper right lung, central liver, and upper liver, the effect of covariance between model and prediction errors in SI direction was around 20%, 30%, 25%, 25%, 25%, and 30%, respectively. Notable covariance effects between model and prediction errors can be considered in PTV margin estimation using a modified VHF, which allowed for more precise target localization in robotic SBRT for moving tumors. Overall, in each of the three directions, the difference between MVHF and utilized clinical margins is 0.65 mm in the lung and abdominal region. Therefore, to improve the clinical PTV margins with the new approach, it is suggested to use the adaptive PTV margins in the next fractions.

Stereotactic body radiotherapy of adrenal metastases-A dose-finding study.

Optimal doses for the treatment of adrenal metastases with stereotactic radiotherapy (SBRT) are unknown. We aimed to identify dose-volume cut-points associated with decreased local recurrence rates (LRR). A multicenter database of patients with adrenal metastases of any histology treated with SBRT (biologically effective dose, BED10 ≥50 Gy, ≤12 fractions) was analyzed. Details on dose-volume parameters were required (planning target volume: PTV-D98%, PTV-D50%, PTV-D2%; gross tumor volume: GTV-D50%, GTV-mean). Cut-points for LRR were optimized using the R maxstat package. One hundred and ninety-six patients with 218 lesions were included, the largest histopathological subgroup was adenocarcinoma (n = 101). Cut-point optimization resulted in significant cut-points for PTV-D50% (BED10: 73.2 Gy; P = .003), GTV-D50% (BED10: 74.2 Gy; P = .006), GTV-mean (BED10: 73.0 Gy; P = .007), and PTV-D2% (BED10: 78.0 Gy; P = .02) but not for the PTV-D98% (P = .06). Differences in LRR were clinically relevant (LRR ≥ doubled for cut-points that were not achieved). Further dose-escalation was not associated with further improved LRR. PTV-D50%, GTV-D50%, and GTV-mean cut-points were also associated with significantly improved LRR in the adenocarcinoma subgroup. Separate dose optimizations indicated a lower cut-point for the PTV-D50% (BED10: 69.1 Gy) in adenocarcinoma lesions, other values were similar (<2% difference). Associations of cut-points with overall survival (OS) and progression-free survival were not significant but durable freedom from local recurrence was associated with OS in a landmark model (P < .001). To achieve a significant improvement of LRR for adrenal SBRT, a moderate escalation of PTV-D50% BED10 >73.2 Gy (adenocarcinoma: 69.1 Gy) should be considered.

Stereotactic or conformal radiotherapy for adrenal metastases: Patient characteristics and outcomes in a multicenter analysis.

To report outcome (freedom from local progression [FFLP], overall survival [OS] and toxicity) after stereotactic, palliative or highly conformal fractionated (>12) radiotherapy (SBRT, Pall-RT, 3DCRT/IMRT) for adrenal metastases in a retrospective multicenter cohort within the framework of the German Society for Radiation Oncology (DEGRO). Adrenal metastases treated with SBRT (≤12 fractions, biologically effective dose [BED10] ≥ 50 Gy), 3DCRT/IMRT (>12 fractions, BED10 ≥ 50 Gy) or Pall-RT (BED10 < 50 Gy) were eligible for this analysis. In addition to unadjusted FFLP (Kaplan-Meier/log-rank), we calculated the competing-risk-adjusted local recurrence rate (CRA-LRR). Three hundred twenty-six patients with 366 metastases were included by 21 centers (median follow-up: 11.7 months). Treatment was SBRT, 3DCRT/IMRT and Pall-RT in 260, 27 and 79 cases, respectively. Most frequent primary tumors were non-small-cell lung cancer (NSCLC; 52.5%), SCLC (16.3%) and melanoma (6.7%). Unadjusted FFLP was higher after SBRT vs Pall-RT (P = .026) while numerical differences in CRA-LRR between groups did not reach statistical significance (1-year CRA-LRR: 13.8%, 17.4% and 27.7%). OS was longer after SBRT vs other groups (P < .05) and increased in patients with locally controlled metastases in a landmark analysis (P < .0001). Toxicity was mostly mild; notably, four cases of adrenal insufficiency occurred, two of which were likely caused by immunotherapy or tumor progression. Radiotherapy for adrenal metastases was associated with a mild toxicity profile in all groups and a favorable 1-year CRA-LRR after SBRT or 3DCRT/IMRT. One-year FFLP was associated with longer OS. Dose-response analyses for the dataset are underway.

Tumor-dose-rate variations during robotic radiosurgery of oligo and multiple brain metastases.

PURPOSE: For step-and-shoot robotic stereotactic radiosurgery (SRS) the dose delivered over time, called local tumor-dose-rate (TDR), may strongly vary during treatment of multiple lesions. The authors sought to evaluate technical parameters influencing TDR and correlate TDR to clinical outcome. MATERIAL AND METHODS: A total of 23 patients with 162 oligo (1-3) and multiple (>3) brain metastases (OBM/MBM) treated in 33 SRS sessions were retrospectively analyzed. Median PTV were 0.11 cc (0.01-6.36 cc) and 0.50 cc (0.12-3.68 cc) for OBM and MBM, respectively. Prescription dose ranged from 16 to 20 Gy prescribed to the median 70% isodose line. The maximum dose-rate for planning target volume (PTV) percentage p in time span s during treatment (TDRs,p) was calculated for various p and s based on treatment log files and in-house software. RESULTS: TDR60min,98% was 0.30 Gy/min (0.23-0.87 Gy/min) for OBM and 0.22 Gy/min (0.12-0.63 Gy/min) for MBM, respectively, and increased by 0.03 Gy/min per prescribed Gy. TDR60min,98% strongly correlated with treatment time (ρ = -0.717, p < 0.001), monitor units (MU) (ρ = -0.767, p < 0.001), number of beams (ρ = -0.755, p < 0.001) and beam directions (ρ = -0.685, p < 0.001) as well as lesions treated per collimator (ρ = -0.708, P < 0.001). Median overall survival (OS) was 20 months and 1­ and 2­year local control (LC) was 98.8% and 90.3%, respectively. LC did not correlate with any TDR, but tumor response (partial response [PR] or complete response [CR]) correlated with all TDR in univariate analysis (e.g., TDR60min,98%: hazard ration [HR] = 0.974, confidence interval [CI] = 0.952-0.996, p = 0.019). In multivariate analysis only concomitant targeted therapy or immunotherapy and breast cancer tumor histology remained a significant factor for tumor response. Local grade ≥2 radiation-induced tissue reactions were noted in 26.3% (OBM) and 5.2% (MBM), respectively, mainly influenced by tumor volume (p < 0.001). CONCLUSIONS: Large TDR variations are noted during MBM-SRS which mainly arise from prolonged treatment times. Clinically, low TDR corresponded with decreased local tumor responses, although the main influencing factor was concomitant medication.

Innovative radiation oncology Together - Precise, Personalized, Human : Vision 2030 for radiotherapy & radiation oncology in Germany.

PURPOSE: Scientific and clinical achievements in radiation, medical, and surgical oncology are changing the landscape of interdisciplinary oncology. The German Society for Radiation Oncology (DEGRO) working group of young clinicians and scientists (yDEGRO) and the DEGRO representation of associate and full professors (AKRO) are aware of the essential role of radiation oncology in multidisciplinary treatment approaches. Together, yDEGRO and AKRO endorsed developing a German radiotherapy & radiation oncology vision 2030 to address future challenges in patient care, research, and education. The vision 2030 aims to identify priorities and goals for the next decade in the field of radiation oncology. METHODS: The vision development comprised three phases. During the first phase, areas of interest, objectives, and the process of vision development were defined jointly by the yDEGRO, AKRO, and the DEGRO board. In the second phase, a one-day strategy retreat was held to develop AKRO and yDEGRO representatives' final vision from medicine, biology, and physics. The third phase was dedicated to vision interpretation and program development by yDEGRO representatives. RESULTS: The strategy retreat's development process resulted in conception of the final vision "Innovative radiation oncology Together - Precise, Personalized, Human." The first term "Innovative radiation oncology" comprises the promotion of preclinical research and clinical trials and highlights the development of a national committee for strategic development in radiation oncology research. The term "together" underpins collaborations within radiation oncology departments as well as with other partners in the clinical and scientific setting. "Precise" mainly covers technological precision in radiotherapy as well as targeted oncologic therapeutics. "Personalized" emphasizes biology-directed individualization of radiation treatment. Finally, "Human" underlines the patient-centered approach and points towards the need for individual longer-term career curricula for clinicians and researchers in the field. CONCLUSION: The vision 2030 balances the ambition of physical, technological, and biological innovation as well as a comprehensive, patient-centered, and collaborative approach towards radiotherapy & radiation oncology in Germany.

Stereotactic radiotherapy combined with immunotherapy or targeted therapy for metastatic renal cell carcinoma.

OBJECTIVES: To evaluate the safety and efficacy of stereotactic radiotherapy (SRT) in patients with metastatic renal cell carcinoma (mRCC) concurrently receiving targeted therapy (TT) or immunotherapy. PATIENTS AND METHODS: Data on patients with mRCC were extracted from a retrospective international multicentre register study (TOaSTT), investigating SRT concurrent (≤30 days) with TT/immune checkpoint inhibitor (ICI) therapy. Overall survival (OS), progression-free survival (PFS), local metastasis control (LC) and time to systemic therapy switch were analysed using Kaplan-Meier curves and log-rank testing. Clinical and treatment factors influencing survival were analysed using multivariate Cox regression. Acute and late SRT-induced toxicity were defined according to the Common Terminology Criteria for Adverse Events v.4.03. RESULTS: Fifty-three patients who underwent 128 sessions of SRT were included, of whom 58% presented with oligometastatic disease (OMD). ICIs and TT were received by 32% and 68% of patients, respectively. Twenty patients (37%) paused TT for a median (range) of 14 (2-21) days. ICI therapy was not paused in any patient. A median (range) of 1 (1-5) metastatic tumour was treated per patient, with a median (range) SRT dose of 65 (40-129.4) Gy (biologically effective dose). The OS, LC and PFS rates at 1 year were 71%, 75% and 25%, respectively. The median OS and PFS were not significantly different among patients receiving TT vs those receiving ICIs (P = 0.329). New lesions were treated with a repeat radiotherapy course in 46% of patients. After 1 year, 62% of patients remained on the same systemic therapy as at the time of SRT; this was more frequent for ICI therapy compared to TT (83% vs 36%; P = 0.035). OMD was an independent prognostic factor for OS (P = 0.004, 95% confidence interval [CI] 0.035-0.528) and PFS (P = 0.004; 95% CI 0.165-0.717) in multivariate analysis. Eastern Cooperative Oncology Group performance status (ECOG-PS) was the other independent prognostic factor for OS (P = 0.001, 95% CI 0.001-0.351). Acute grade 3 toxicity was observed in two patients, and late grade 3 toxicity in one patient. No grade 4 or 5 toxicity was observed. CONCLUSION: Combined treatment with TT or immunotherapy and concurrent SRT was safe, without signals of increased severe toxicity. As we observed no signal of excess toxicity, full-dose SRT should be considered to achieve optimal metastasis control in patients receiving TT or immunotherapy. Favourable PFS and OS were observed for patients with oligometastatic RCC with a good ECOG-PS, which should form the basis for prospective testing of this treatment strategy in properly designed clinical trials.

MRI characteristics in treatment for cerebral melanoma metastasis using stereotactic radiosurgery and concomitant checkpoint inhibitors or targeted therapeutics.

INTRODUCTION: Combination therapy for melanoma brain metastases (MM) using stereotactic radiosurgery (SRS) and immune checkpoint-inhibition (ICI) or targeted therapy (TT) is currently of high interest. In this collective, time evolution and incidence of imaging findings indicative of pseudoprogression is sparsely researched. We therefore investigated time-course of MRI characteristics in these patients. METHODS: Data were obtained retrospectively from 27 patients (12 female, 15 male; mean 61 years, total of 169 MMs). Single lesion volumes, total MM burden and edema volumes were analyzed at baseline and follow-up MRIs in 2 months intervals after SRS up to 24 months. The occurrence of intralesional hemorrhages was recorded. RESULTS: 17 patients (80 MM) received ICI, 8 (62 MM) TT and 2 (27 MM) ICI + TT concomitantly to SRS. MM-localization was frontal (n = 89), temporal (n = 23), parietal (n = 20), occipital (n = 10), basal ganglia/thalamus/insula (n = 10) and cerebellar (n = 10). A volumetric progression of MM 2-4 months after SRS was observed in combined treatment with ICI (p = 0.028) and ICI + TT (p = 0.043), whereas MMs treated with TT showed an early volumetric regression (p = 0.004). Edema volumes moderately correlated with total MM volumes (r = 0.57; p < 0.0001). Volumetric behavior did not differ significantly over time regarding lesions' initial sizes or localizations. No significant differences between groups were observed regarding rates of post-SRS intralesional hemorrhages. CONCLUSION: Reversible volumetric increases in terms of pseudoprogression are observed 2-4 months after SRS in patients with MM concomitantly treated with ICI and ICI + TT, rarely after TT. Edema volumes mirror total MM volumes. Medical treatment type does not significantly affect rates of intralesional hemorrhage.

Stereotactic body radiotherapy for ventricular tachycardia (cardiac radiosurgery) : First-in-patient treatment in Germany.

PURPOSE: Single-session cardiac stereotactic body radiotherapy, called cardiac radiosurgery (CRS) or radioablation (RA), may offer a potential treatment option for patients with refractory ventricular tachycardia (VT) and electrical storm who are otherwise ineligible for catheter ablation. However, there is only limited clinical experience. We now present the first-in-patient treatment using (CRS/RA) for VT in Germany. METHODS: A 78-year-old male patient with dilated cardiomyopathy and significantly reduced ejection fraction (15%) presented with monomorphic VT refractory to poly-anti-arrhythmic medication and causing multiple implantable cardioverter-defibrillator (ICD) interventions over the course of several weeks, necessitating prolonged treatment on an intensive care unit. Ultra-high-resolution electroanatomical voltage mapping (EVM) revealed a re-entry circuit in the cardiac septum inaccessible for catheter ablation. Based on the EVM, CRS/RA with a single session dose of 25 Gy (83% isodose) was delivered to the VT substrate (8.1 cc) using a c-arm-based high-precision linear accelerator on November 30, 2018. RESULTS: CRS/RA was performed without incident and dysfunction of the ICD was not observed. Following the procedure, a significant reduction in monomorphic VT from 5.0 to 1.6 episodes per week and of ICD shock interventions by 81.2% was observed. Besides periprocedural nausea with a single episode of vomiting, no treatment-associated side effects were noted. Unfortunately, the patient died 57 days after CRS/RA due to sepsis-associated cardiac circulatory failure after Clostridium difficile-associated colitis developed during rehabilitation. Histopathologic examination of the heart as part of a clinical autopsy revealed diffuse fibrosis on most sections of the heart without apparent differences between the target area and the posterior cardiac wall serving as a control. CONCLUSION: CRS/RA appears to be a possible treatment option for otherwise untreatable patients suffering from refractory VT and electrical storm. A relevant reduction in VT incidence and ICD interventions was observed, although long-term outcome and consequences of CRS/RA remain unclear. Clinical trials are strongly warranted and have been initiated.

Definition and quality requirements for stereotactic radiotherapy: consensus statement from the DEGRO/DGMP Working Group Stereotactic Radiotherapy and Radiosurgery.

Stereotactic radiotherapy with its forms of intracranial stereotactic radiosurgery (SRS), intracranial fractionated stereotactic radiotherapy (FSRT) and stereotactic body radiotherapy (SBRT) is today a guideline-recommended treatment for malignant or benign tumors as well as neurological or vascular functional disorders. The working groups for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO) and for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP) have established a consensus statement about the definition and minimal quality requirements for stereotactic radiotherapy to achieve best clinical outcome and treatment quality in the implementation into routine clinical practice.

Technological quality requirements for stereotactic radiotherapy : Expert review group consensus from the DGMP Working Group for Physics and Technology in Stereotactic Radiotherapy.

This review details and discusses the technological quality requirements to ensure the desired quality for stereotactic radiotherapy using photon external beam radiotherapy as defined by the DEGRO Working Group Radiosurgery and Stereotactic Radiotherapy and the DGMP Working Group for Physics and Technology in Stereotactic Radiotherapy. The covered aspects of this review are 1) imaging for target volume definition, 2) patient positioning and target volume localization, 3) motion management, 4) collimation of the irradiation and beam directions, 5) dose calculation, 6) treatment unit accuracy, and 7) dedicated quality assurance measures. For each part, an expert review for current state-of-the-art techniques and their particular technological quality requirement to reach the necessary accuracy for stereotactic radiotherapy divided into intracranial stereotactic radiosurgery in one single fraction (SRS), intracranial fractionated stereotactic radiotherapy (FSRT), and extracranial stereotactic body radiotherapy (SBRT) is presented. All recommendations and suggestions for all mentioned aspects of stereotactic radiotherapy are formulated and related uncertainties and potential sources of error discussed. Additionally, further research and development needs in terms of insufficient data and unsolved problems for stereotactic radiotherapy are identified, which will serve as a basis for the future assignments of the DGMP Working Group for Physics and Technology in Stereotactic Radiotherapy. The review was group peer-reviewed, and consensus was obtained through multiple working group meetings.