A prediction model for response to immune checkpoint inhibition in advanced melanoma.

Predicting who will benefit from treatment with immune checkpoint inhibition (ICI) in patients with advanced melanoma is challenging. We developed a multivariable prediction model for response to ICI, using routinely available clinical data including primary melanoma characteristics. We used a population-based cohort of 3525 patients with advanced cutaneous melanoma treated with anti-PD-1-based therapy. Our prediction model for predicting response within 6 months after ICI initiation was internally validated with bootstrap resampling. Performance evaluation included calibration, discrimination and internal-external cross-validation. Included patients received anti-PD-1 monotherapy (n = 2366) or ipilimumab plus nivolumab (n = 1159) in any treatment line. The model included serum lactate dehydrogenase, World Health Organization performance score, type and line of ICI, disease stage and time to first distant recurrence-all at start of ICI-, and location and type of primary melanoma, the presence of satellites and/or in-transit metastases at primary diagnosis and sex. The over-optimism adjusted area under the receiver operating characteristic was 0.66 (95% CI: 0.64-0.66). The range of predicted response probabilities was 7%-81%. Based on these probabilities, patients were categorized into quartiles. Compared to the lowest response quartile, patients in the highest quartile had a significantly longer median progression-free survival (20.0 vs 2.8 months; P < .001) and median overall survival (62.0 vs 8.0 months; P < .001). Our prediction model, based on routinely available clinical variables and primary melanoma characteristics, predicts response to ICI in patients with advanced melanoma and discriminates well between treated patients with a very good and very poor prognosis.

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.

From algorithms to action: improving patient care requires causality.

In cancer research there is much interest in building and validating outcome prediction models to support treatment decisions. However, because most outcome prediction models are developed and validated without regard to the causal aspects of treatment decision making, many published outcome prediction models may cause harm when used for decision making, despite being found accurate in validation studies. Guidelines on prediction model validation and the checklist for risk model endorsement by the American Joint Committee on Cancer do not protect against prediction models that are accurate during development and validation but harmful when used for decision making. We explain why this is the case and how to build and validate models that are useful for decision making.

Designing clinical trials based on modern imaging and metastasis-directed treatments in patients with oligometastatic breast cancer: a consensus recommendation from the EORTC Imaging and Breast Cancer Groups.

Breast cancer remains the most common cause of cancer death among women. Despite its considerable histological and molecular heterogeneity, those characteristics are not distinguished in most definitions of oligometastatic disease and clinical trials of oligometastatic breast cancer. After an exhaustive review of the literature covering all aspects of oligometastatic breast cancer, 35 experts from the European Organisation for Research and Treatment of Cancer Imaging and Breast Cancer Groups elaborated a Delphi questionnaire aimed at offering consensus recommendations, including oligometastatic breast cancer definition, optimal diagnostic pathways, and clinical trials required to evaluate the effect of diagnostic imaging strategies and metastasis-directed therapies. The main recommendations are the introduction of modern imaging methods in metastatic screening for an earlier diagnosis of oligometastatic breast cancer and the development of prospective trials also considering the histological and molecular complexity of breast cancer. Strategies for the randomisation of imaging methods and therapeutic approaches in different subsets of patients are also addressed.

Time interval from primary melanoma to first distant recurrence in relation to patient outcomes in advanced melanoma.

Since the introduction of BRAF(/MEK) inhibition and immune checkpoint inhibition (ICI), the prognosis of advanced melanoma has greatly improved. Melanoma is known for its remarkably long time to first distant recurrence (TFDR), which can be decades in some patients and is partly attributed to immune-surveillance. We investigated the relationship between TFDR and patient outcomes after systemic treatment for advanced melanoma. We selected patients undergoing first-line systemic therapy for advanced melanoma from the nationwide Dutch Melanoma Treatment Registry. The association between TFDR and progression-free survival (PFS) and overall survival (OS) was assessed by Cox proportional hazard regression models. The TFDR was modeled categorically, linearly, and flexibly using restricted cubic splines. Patients received anti-PD-1-based treatment (n = 1844) or BRAF(/MEK) inhibition (n = 1618). For ICI-treated patients with a TFDR <2 years, median OS was 25.0 months, compared to 37.3 months for a TFDR >5 years (P = .014). Patients treated with BRAF(/MEK) inhibition with a longer TFDR also had a significantly longer median OS (8.6 months for TFDR <2 years compared to 11.1 months for >5 years, P = .004). The hazard of dying rapidly decreased with increasing TFDR until approximately 5 years (HR 0.87), after which the hazard of dying further decreased with increasing TFDR, but less strongly (HR 0.82 for a TFDR of 10 years and HR 0.79 for a TFDR of 15 years). Results were similar when stratifying for type of treatment. Advanced melanoma patients with longer TFDR have a prolonged PFS and OS, irrespective of being treated with first-line ICI or targeted therapy.

Different profiles of neurocognitive functioning in patients with brain metastases prior to brain radiotherapy.

OBJECTIVE: Patients with brain metastases (BrMs) are a heterogeneous population, with almost 50% experiencing cognitive impairment before brain radiotherapy. Defining pre-radiotherapy cognitive profiles will aid in understanding of the cognitive vulnerabilities and offer valuable insight and guidance for tailoring interventions. METHODS: The study population consisted of 58 adult patients with BrMs referred for radiotherapy. A semi-structured interview and comprehensive battery including 10 neuropsychological tests were used to assess subjective and objective cognitive performance prior to radiotherapy. RESULTS: A majority (69%) of patients report decline in cognitive performance compared to their premorbid level (i.e. pre-cancer). Objective testing revealed memory (52%), processing speed (33%) and emotion recognition (29%) deficits were most frequent. 21% of patients had no cognitive deficits while 55% had deficits (-1.5SD) in at least two cognitive domains. Hierarchical cluster analysis based on patient deficit profiles identified four clusters: (I) no or limited cognitive deficits selectively restricted to processing speed or executive function, (II) psychomotor speed deficits, (III) memory deficits and (IV) extensive cognitive deficits including memory. No patient or clinical-related (e.g. age, number of BrMs, previous treatment) differences were found between clusters. CONCLUSIONS: Patterns of cognitive performance in patients with BrMs are heterogeneous, with most experiencing at least some degree of neurocognitive dysfunction. We identified four meaningful cognitive clusters. Stability of these clusters over time and in different samples should be assessed to advance understanding of the cognitive vulnerability of this patient population.

Recurrences of ventricular tachycardia after stereotactic arrhythmia radioablation arise outside the treated volume: analysis of the Swiss cohort.

AIMS: Stereotactic arrhythmia radioablation (STAR) has been recently introduced for the management of therapy-refractory ventricular tachycardia (VT). VT recurrences have been reported after STAR but the mechanisms remain largely unknown. We analysed recurrences in our patients after STAR. METHODS AND RESULTS: From 09.2017 to 01.2020, 20 patients (68 ± 8 y, LVEF 37 ± 15%) suffering from refractory VT were enrolled, 16/20 with a history of at least one electrical storm. Before STAR, an invasive electroanatomical mapping (Carto3) of the VT substrate was performed. A mean dose of 23 ± 2 Gy was delivered to the planning target volume (PTV). The median ablation volume was 26 mL (range 14-115) and involved the interventricular septum in 75% of patients. During the first 6 months after STAR, VT burden decreased by 92% (median value, from 108 to 10 VT/semester). After a median follow-up of 25 months, 12/20 (60%) developed a recurrence and underwent a redo ablation. VT recurrence was located in the proximity of the treated substrate in nine cases, remote from the PTV in three cases and involved a larger substrate over ≥3 LV segments in two cases. No recurrences occurred inside the PTV. Voltage measurements showed a significant decrease in both bipolar and unipolar signal amplitude after STAR. CONCLUSION: STAR is a new tool available for the treatment of VT, allowing for a significant reduction of VT burden. VT recurrences are common during follow-up, but no recurrences were observed inside the PTV. Local efficacy was supported by a significant decrease in both bipolar and unipolar signal amplitude.

Feasibility and first results of the 'Trials-within-Cohorts' (TwiCs) design in patients undergoing radiotherapy for lung cancer.

Background: 'Trials-within-Cohorts' (TwiCs), previously known as 'cohort multiple randomized controlled trials' is a pragmatic trial design, supporting an efficient and representative recruitment of patients for (future) trials. To our knowledge, the 'COhort for Lung cancer Outcome Reporting and trial inclusion' (COLOR) is the first TwiCs in lung cancer patients. In this study we aimed to assess the feasibility and first year results of COLOR.Material and Methods: All patients diagnosed with lung cancer referred to the Radiotherapy department were eligible to participate in the ongoing prospective COLOR study. At inclusion, written informed consent was requested for use of patient data, participation in patient-reported outcomes (PROs), and willingness to participate in (future) trials. Feasibility was studied by assessing participation and comparing baseline PROs to EORTC reference values. First-year results of PROs at baseline and 3 months after inclusion were evaluated separately for stereotactic body radiotherapy (SBRT) and conventional radiotherapy patients.Results: Of the 338 eligible patients between July 2020 and July 2021, 169 (50%) participated. Among these, 127 (75%) gave informed consent to PROs participation and 110 (65%) were willing to participate in (future) trials. The inclusion percentage dropped from 77% to 33% when the information procedure was switched from in-person to by phone (due to COVID-19 pandemic measures). Baseline PROs for physical and cognitive functioning were comparable in COLOR patients compared to the EORTC reference values. No significant changes in PROs were observed 3 months after inclusion, except for a slight increase in pain scores in the SBRT group (n = 97).Conclusions: The TwiCs-design appears feasible in lung cancer patients with fair participation rates (although negatively impacted by the COVID-19 pandemic). With a planned expansion to other centers, the COLOR-study is expected to enable multiple (randomized) evaluations of experimental interventions with important advantages for recruitment, generalizability, and long-term outcome data collection.

Non-Small-Cell Lung Cancer Patients with a High Predicted Risk of Irradical Resection: Can Chemoradiotherapy Offer Similar Survival?

PURPOSE: Irradical resection of non-small-cell lung cancer (NSCLC) is a detrimental prognostic factor. Recently, Rasing et al. presented an internationally validated risk score for pre-treatment prediction of irradical resection. We hypothesized that chemoradiation therapy (CRT) could serve as an alternative approach in patients with a high risk score and compared overall survival (OS) outcomes between surgery and CRT. METHODS: Patients from a population-based cohort with stage IIB-III NSCLC between 2015 and 2018 in The Netherlands were selected. Patients with a 'Rasing score' > 4 who underwent surgery were matched with patients who underwent CRT using 1:1 nearest-neighbor propensity score matching. The primary endpoint of OS was compared using a Kaplan-Meier analysis. RESULTS: In total, 2582 CRT and 638 surgery patients were eligible. After matching, 523 well-balanced pairs remained. Median OS in the CRT group was 27.5 months, compared with 45.6 months in the surgery group (HR 1.44, 95% CI 1.23-1.70, p < 0.001). The 114 surgical patients who underwent an R1-2 resection (21.8%) had a worse median OS than the CRT group (20.2 versus 27.5 months, HR 0.77, 95% CI 0.61-0.99, p = 0.039). CONCLUSION: In NSCLC patients at high predicted risk of irradical resection, CRT appears to yield inferior survival compared with surgery. Therefore, choosing CRT instead of surgery cannot solely be based on the Rasing score. Since patients receiving an R1-2 resection do have detrimental outcomes compared with primary CRT, the treatment decision should be based on additional information, such as imaging features, comorbidities, patient preference, and the surgeon's confidence in achieving an R0 resection.

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.

Ultra-central lung tumors: safety and efficacy of protracted stereotactic body radiotherapy.

BACKGROUND: For patients with early stage or medically inoperable lung cancer, stereotactic body radiotherapy (SBRT) is a general accepted and effective treatment option. The role of SBRT in ultra-central tumors remains controversial. The aim of this single-center retrospective analysis was to evaluate the safety and efficacy of protracted SBRT with 60 Gy in 12 fractions (with a biological effective dose (BED10) of 90-150 Gy) for patients with ultra-central lung tumors. MATERIALS AND METHODS: Patients with ultra-central lung tumors treated in our institution with 60 Gy in 12 fractions from January 2012 until April 2020 were included. Ultra-central tumors were defined as planning target volume (PTV) abutting or overlapping the main bronchi and/or trachea and/or esophagus. Data regarding patient-, tumor-, and treatment-related characteristics were evaluated. RESULTS: A total of 72 patients met the criteria for ultra-central tumor location. The PTV abutted the main bronchus, trachea or esophagus in 79%, 22% and 28% of cases, respectively. At a median follow-up of 19 months, 1- and 2-year local control rates were 98% and 85%, respectively. Overall survival rates at 1 and 2 years were 77% and 52%, respectively. Grade 3 or higher toxicity was observed in 21%, of which 10 patients (14% of total) died of bronchopulmonary hemorrhage. A significant difference between patients with or without grade ≥3 toxicity was found for the mean dose (Dmean) to the main bronchus (p = 0.003), where a Dmean BED3 of ≥91 Gy increased the risk of grade ≥3 toxicity significantly. DISCUSSION: A protracted SBRT regimen of 60 Gy in 12 fractions for ultra-central lung tumors leads to high local control rates with toxicity rates similar to previous series, but with substantial risk of fatal bronchopulmonary hemorrhage. Therefore, possible risk factors of bronchopulmonary hemorrhage such as dose to the main bronchus should be taken into account.

Untangling the diffusion signal using the phasor transform.

Separating the decay signal from diffusion-weighted scans into two or more components can be challenging. The phasor technique is well established in the field of optical microscopy for visualization and separation of fluorescent dyes with different lifetimes. The use of the phasor technique for separation of diffusion-weighted decay signals was recently proposed. In this study, we investigate the added value of this technique for fitting decay models and visualization of decay rates. Phasor visualization was performed in five glioblastoma patients. Using simulations, the influence of incorrect diffusivity values and of the number of b-values on fitting a three-component model with fixed diffusivities (dubbed "unmixing") was investigated for both a phasor-based fit and a linear least squares (LLS) fit. Phasor-based intravoxel incoherent motion (IVIM) fitting was compared with nonlinear least squares (NLLS) and segmented fitting (SF) methods in terms of accuracy and precision. The distributions of the parameter estimates of simulated data were compared with those obtained in a healthy volunteer. In the phasor visualizations of two glioblastoma patients, a cluster of points was observed that was not seen in healthy volunteers. The identified cluster roughly corresponded to the enhanced edge region of the tumor of two glioblastoma patients visible on fluid-attenuated inversion recovery (FLAIR) images. For fitting decay models the usefulness of the phasor transform is less pronounced, but the additional knowledge gained from the geometrical configuration of phasor space can aid fitting routines. This has led to slightly improved fitting results for the IVIM model: phasor-based fitting yielded parameter maps with higher precision than the NLLS and SF methods for parameters f and D (interquartile range [IQR] for f: NLLS 27, SF 12, phasor 5.7%; IQR for D: NLLS 0.28, SF 0.18, phasor 0.10 µm2 /s). For unmixing, LLS fitting slightly but consistently outperformed phasor-based fitting in all of the tested scenarios.

Glioma consensus contouring recommendations from a MR-Linac International Consortium Research Group and evaluation of a CT-MRI and MRI-only workflow.

INTRODUCTION: This study proposes contouring recommendations for radiation treatment planning target volumes and organs-at-risk (OARs) for both low grade and high grade gliomas. METHODS: Ten cases consisting of 5 glioblastomas and 5 grade II or III gliomas, including their respective gross tumor volume (GTV), clinical target volume (CTV), and OARs were each contoured by 6 experienced neuro-radiation oncologists from 5 international institutions. Each case was first contoured using only MRI sequences (MRI-only), and then re-contoured with the addition of a fused planning CT (CT-MRI). The level of agreement among all contours was assessed using simultaneous truth and performance level estimation (STAPLE) with the kappa statistic and Dice similarity coefficient. RESULTS: A high level of agreement was observed between the GTV and CTV contours in the MRI-only workflow with a mean kappa of 0.88 and 0.89, respectively, with no statistically significant differences compared to the CT-MRI workflow (p = 0.88 and p = 0.82 for GTV and CTV, respectively). Agreement in cochlea contours improved from a mean kappa of 0.39 to 0.41, to 0.69 to 0.71 with the addition of CT information (p < 0.0001 for both cochleae). Substantial to near perfect level of agreement was observed in all other contoured OARs with a mean kappa range of 0.60 to 0.90 in both MRI-only and CT-MRI workflows. CONCLUSIONS: Consensus contouring recommendations for low grade and high grade gliomas were established using the results from the consensus STAPLE contours, which will serve as a basis for further study and clinical trials by the MR-Linac Consortium.

Survival after whole brain radiotherapy for brain metastases from lung cancer and breast cancer is poor in 6325 Dutch patients treated between 2000 and 2014.

BACKGROUND: Whole brain radiotherapy (WBRT) is considered standard of care for patients with multiple brain metastases or unfit for radical treatment modalities. Recent studies raised discussion about the expected survival after WBRT. Therefore, we analysed survival after WBRT for brain metastases 'in daily practice' in a large nationwide multicentre retrospective cohort. METHODS: Between 2000 and 2014, 6325 patients had WBRT (20 Gy in 4 Gy fractions) for brain metastases from non-small cell lung cancer (NSCLC; 4363 patients) or breast cancer (BC; 1962 patients); patients were treated in 15 out of 21 Dutch radiotherapy centres. Survival was calculated by the Kaplan-Meier method from the first day of WBRT until death as recorded in local hospital data registration or the Dutch Municipal Personal Records Database. FINDINGS: The median survival was 2.7 months for NSCLC and 3.7 months for BC patients (p < .001). For NSCLC patients aged <50, 50-60, 60-70 and >70 years, survival was 4.0, 3.0, 2.8 and 2.1 months, respectively (p < .001). For BC patients, survival was 4.5, 3.8, 3.2 and 2.9 months, respectively (p = .047). In multivariable analyses, higher age was related to poorer survival with hazard ratios (HR) for patients aged 50-60, 60-70 and >70 years being 1.05, 1.19 and 1.34, respectively. Primary BC (HR: 0.83) and female sex (HR: 0.85) were related to better survival (p < .001). INTERPRETATION: The survival of patients after WBRT for brain metastases from NSCLC treated in Dutch 'common radiotherapy practice' is poor, in breast cancer and younger patients it is disappointingly little better. These results are in line with the results presented in the QUARTZ trial and we advocate a much more restrictive use of WBRT. In patients with a more favourable prognosis the optimal treatment strategy remains to be determined. Prospective randomized trials and individualized prognostic models are needed to identify these patients and to tailor treatment.

Bevacizumab in combination with radiotherapy and temozolomide for patients with newly diagnosed glioblastoma multiforme.

BACKGROUND: Patients with a newly diagnosed glioblastoma multiforme (GBM) have a high risk of recurrent disease with a dismal outcome despite intensive treatment of sequential surgery and chemoradiotherapy with temozolomide (TMZ), followed by TMZ as a single agent. Bevacizumab (BV) may increase response rates to chemotherapy in the recurrent treatment setting of GBM. We hypothesized that a neoadjuvant treatment strategy for patients with newly diagnosed GBM using chemoradiotherapy plus BV would improve resectability and thus survival. We performed a phase II trial of the treatment strategy of BV plus chemoradiation to determine the safety of this combination in patients who had already undergone primary surgery for their GBM. METHODS: After a biopsy (6 patients) or a resection (13 patients) of a newly diagnosed GBM, 19 patients received radiotherapy (30 fractions of 2 Gy) in combination with daily TMZ 75 mg/m(2) and BV 10 mg/kg on days 1, 14, and 28, followed by 6 monthly cycles of TMZ 150-200 mg/m(2) on days 1-5. RESULTS: The overall response rate was 26%. Three patients had a complete response after resection, and in two patients, a complete response after resection followed by chemoradiation plus BV was seen. No grade 3-4 toxicities were observed during combination treatment. The median progression-free survival was 9.6 months (95% confidence interval [CI]: 4.3-14.4 months). The median overall survival was 16 months (95% CI: 8.1-26.3 months), similar to a matched control group that received standard chemoradiotherapy from our institution. CONCLUSION: Combination of bevacizumab with radiotherapy and TMZ is safe and feasible in patients with newly diagnosed GBM, but because of low response rates, this treatment strategy does not favor a neoadjuvant approach.

Stereotactic Body and Conventional Radiotherapy for Painful Bone Metastases: A Systematic Review and Meta-Analysis.

Importance: Conventional external beam radiotherapy (cEBRT) and stereotactic body radiotherapy (SBRT) are commonly used treatment options for relieving metastatic bone pain. The effectiveness of SBRT compared with cEBRT in pain relief has been a subject of debate, and conflicting results have been reported. Objective: To compare the effectiveness associated with SBRT vs cEBRT for relieving metastatic bone pain. Data Sources: A structured search was performed in the PubMed, Embase, and Cochrane databases on June 5, 2023. Additionally, results were added from a new randomized clinical trial (RCT) and additional unpublished data from an already published RCT. Study Selection: Comparative studies reporting pain response after SBRT vs cEBRT in patients with painful bone metastases. Data Extraction and Synthesis: Two independent reviewers extracted data from eligible studies. Data were extracted for the intention-to-treat (ITT) and per-protocol (PP) populations. The study is reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Main Outcomes and Measures: Overall and complete pain response at 1, 3, and 6 months after radiotherapy, according to the study's definition. Relative risk ratios (RRs) with 95% CIs were calculated for each study. A random-effects model using a restricted maximum likelihood estimator was applied for meta-analysis. Results: There were 18 studies with 1685 patients included in the systematic review and 8 RCTs with 1090 patients were included in the meta-analysis. In 7 RCTs, overall pain response was defined according to the International Consensus on Palliative Radiotherapy Endpoints in clinical trials (ICPRE). The complete pain response was reported in 6 RCTs, all defined according to the ICPRE. The ITT meta-analyses showed that the overall pain response rates did not differ between cEBRT and SBRT at 1 (RR, 1.14; 95% CI, 0.99-1.30), 3 (RR, 1.19; 95% CI, 0.96-1.47), or 6 (RR, 1.22; 95% CI, 0.96-1.54) months. However, SBRT was associated with a higher complete pain response at 1 (RR, 1.43; 95% CI, 1.02-2.01), 3 (RR, 1.80; 95% CI, 1.16-2.78), and 6 (RR, 2.47; 95% CI, 1.24-4.91) months after radiotherapy. The PP meta-analyses showed comparable results. Conclusions and Relevance: In this systematic review and meta-analysis, patients with painful bone metastases experienced similar overall pain response after SBRT compared with cEBRT. More patients had complete pain alleviation after SBRT, suggesting that selected subgroups will benefit from SBRT.

A Framework for Assessing the Effect of Cardiac and Respiratory Motion for Stereotactic Arrhythmia Radioablation Using a Digital Phantom With a 17-Segment Model: A STOPSTORM.eu Consortium Study.

PURPOSE: The optimal motion management strategy for patients receiving stereotactic arrhythmia radioablation (STAR) for the treatment of ventricular tachycardia (VT) is not fully known. We developed a framework using a digital phantom to simulate cardiorespiratory motion in combination with different motion management strategies to gain insight into the effect of cardiorespiratory motion on STAR. METHODS AND MATERIALS: The 4-dimensional (4D) extended cardiac-torso (XCAT) phantom was expanded with the 17-segment left ventricular (LV) model, which allowed placement of STAR targets in standardized ventricular regions. Cardiac- and respiratory-binned 4D computed tomography (CT) scans were simulated for free-breathing, reduced free-breathing, respiratory-gating, and breath-hold scenarios. Respiratory motion of the heart was set to population-averaged values of patients with VT: 6, 2, and 1 mm in the superior-inferior, posterior-anterior, and left-right direction, respectively. Cardiac contraction was adjusted by reducing LV ejection fraction to 35%. Target displacement was evaluated for all segments using envelopes encompassing the cardiorespiratory motion. Envelopes incorporating only the diastole plus respiratory motion were created to simulate the scenario where cardiac motion is not fully captured on 4D respiratory CT scans used for radiation therapy planning. RESULTS: The average volume of the 17 segments was 6 cm3 (1-9 cm3). Cardiac contraction-relaxation resulted in maximum segment (centroid) motion of 4, 6, and 3.5 mm in the superior-inferior, posterior-anterior, and left-right direction, respectively. Cardiac contraction-relaxation resulted in a motion envelope increase of 49% (24%-79%) compared with individual segment volumes, whereas envelopes increased by 126% (79%-167%) if respiratory motion also was considered. Envelopes incorporating only the diastole and respiration motion covered on average 68% to 75% of the motion envelope. CONCLUSIONS: The developed LV-segmental XCAT framework showed that free-wall regions display the most cardiorespiratory displacement. Our framework supports the optimization of STAR by evaluating the effect of (cardio)respiratory motion and motion management strategies for patients with VT.

Exploring contrast generalisation in deep learning-based brain MRI-to-CT synthesis.

BACKGROUND: Synthetic computed tomography (sCT) has been proposed and increasingly clinically adopted to enable magnetic resonance imaging (MRI)-based radiotherapy. Deep learning (DL) has recently demonstrated the ability to generate accurate sCT from fixed MRI acquisitions. However, MRI protocols may change over time or differ between centres resulting in low-quality sCT due to poor model generalisation. PURPOSE: investigating domain randomisation (DR) to increase the generalisation of a DL model for brain sCT generation. METHODS: CT and corresponding T1-weighted MRI with/without contrast, T2-weighted, and FLAIR MRI from 95 patients undergoing RT were collected, considering FLAIR the unseen sequence where to investigate generalisation. A "Baseline" generative adversarial network was trained with/without the FLAIR sequence to test how a model performs without DR. Image similarity and accuracy of sCT-based dose plans were assessed against CT to select the best-performing DR approach against the Baseline. RESULTS: The Baseline model had the poorest performance on FLAIR, with mean absolute error (MAE) = 106 ± 20.7 HU (mean ±σ). Performance on FLAIR significantly improved for the DR model with MAE = 99.0 ± 14.9 HU, but still inferior to the performance of the Baseline+FLAIR model (MAE = 72.6 ± 10.1 HU). Similarly, an improvement in γ-pass rate was obtained for DR vs Baseline. CONCLUSION: DR improved image similarity and dose accuracy on the unseen sequence compared to training only on acquired MRI. DR makes the model more robust, reducing the need for re-training when applying a model on sequences unseen and unavailable for retraining.

Accelerated respiratory-resolved 4D-MRI with separable spatio-temporal neural networks.

BACKGROUND: Respiratory-resolved four-dimensional magnetic resonance imaging (4D-MRI) provides essential motion information for accurate radiation treatments of mobile tumors. However, obtaining high-quality 4D-MRI suffers from long acquisition and reconstruction times. PURPOSE: To develop a deep learning architecture to quickly acquire and reconstruct high-quality 4D-MRI, enabling accurate motion quantification for MRI-guided radiotherapy (MRIgRT). METHODS: A small convolutional neural network called MODEST is proposed to reconstruct 4D-MRI by performing a spatial and temporal decomposition, omitting the need for 4D convolutions to use all the spatio-temporal information present in 4D-MRI. This network is trained on undersampled 4D-MRI after respiratory binning to reconstruct high-quality 4D-MRI obtained by compressed sensing reconstruction. The network is trained, validated, and tested on 4D-MRI of 28 lung cancer patients acquired with a T1-weighted golden-angle radial stack-of-stars (GA-SOS) sequence. The 4D-MRI of 18, 5, and 5 patients were used for training, validation, and testing. Network performances are evaluated on image quality measured by the structural similarity index (SSIM) and motion consistency by comparing the position of the lung-liver interface on undersampled 4D-MRI before and after respiratory binning. The network is compared to conventional architectures such as a U-Net, which has 30 times more trainable parameters. RESULTS: MODEST can reconstruct high-quality 4D-MRI with higher image quality than a U-Net, despite a thirty-fold reduction in trainable parameters. High-quality 4D-MRI can be obtained using MODEST in approximately 2.5 min, including acquisition, processing, and reconstruction. CONCLUSION: High-quality accelerated 4D-MRI can be obtained using MODEST, which is particularly interesting for MRIgRT.