[177Lu]Lu-DOTA-TATE plus long-acting octreotide versus high­dose long-acting octreotide for the treatment of newly diagnosed, advanced grade 2-3, well-differentiated, gastroenteropancreatic neuroendocrine tumours (NETTER-2): an open-label, randomised, phase 3 study.

BACKGROUND: There are currently no standard first-line treatment options for patients with higher grade 2-3, well-differentiated, advanced, gastroenteropancreatic neuroendocrine tumours. We aimed to investigate the efficacy and safety of first-line [177Lu]Lu-DOTA-TATE (177Lu-Dotatate) treatment. METHODS: NETTER-2 was an open-label, randomised, parallel-group, superiority, phase 3 trial. We enrolled patients (aged ≥15 years) with newly diagnosed higher grade 2 (Ki67 ≥10% and ≤20%) and grade 3 (Ki67 >20% and ≤55%), somatostatin receptor-positive (in all target lesions), advanced gastroenteropancreatic neuroendocrine tumours from 45 centres across nine countries in North America, Europe, and Asia. We used interactive response technologies to randomly assign (2:1) patients to receive four cycles (cycle interval was 8 weeks ± 1 week) of intravenous 177Lu-Dotatate plus intramuscular octreotide 30 mg long-acting repeatable (LAR) then octreotide 30 mg LAR every 4 weeks (177Lu-Dotatate group) or high-dose octreotide 60 mg LAR every 4 weeks (control group), stratified by neuroendocrine tumour grade (2 vs 3) and origin (pancreas vs other). Tumour assessments were done at baseline, week 16, and week 24, and then every 12 weeks until disease progression or death. The primary endpoint was progression-free survival by blinded, independent, central radiology assessment. We did the primary analysis at 101 progression-free survival events as the final progression-free survival analysis. NETTER-2 is registered with ClinicalTrials.gov, NCT03972488, and is active and not recruiting. FINDINGS: Between Jan 22, 2020, and Oct 13, 2022, we screened 261 patients, 35 (13%) of whom were excluded. We randomly assigned 226 (87%) patients (121 [54%] male and 105 [46%] female) to the 177Lu-Dotatate group (n=151 [67%]) and control group (n=75 [33%]). Median progression-free survival was 8·5 months (95% CI 7·7-13·8) in the control group and 22·8 months (19·4-not estimated) in the 177Lu-Dotatate group (stratified hazard ratio 0·276 [0·182-0·418]; p<0·0001). During the treatment period, adverse events (of any grade) occurred in 136 (93%) of 147 treated patients in the 177Lu-Dotatate group and 69 (95%) of 73 treated patients in the control group. There were no study drug-related deaths during the treatment period. INTERPRETATION: First-line 177Lu-Dotatate plus octreotide LAR significantly extended median progression-free survival (by 14 months) in patients with grade 2 or 3 advanced gastroenteropancreatic neuroendocrine tumours. 177Lu-Dotatate should be considered a new standard of care in first-line therapy in this population. FUNDING: Advanced Accelerator Applications, a Novartis Company.

Utility of molecular markers in predicting local control specific to lung cancer spine metastases treated with stereotactic body radiotherapy.

BACKGROUND AND PURPOSE: We report outcomes following spine stereotactic body radiotherapy (SBRT) in metastatic non-small cell lung cancer (NSCLC) and the significance of programmed death-ligand 1 (PD-L1) status, epidermal growth factor receptor (EGFR) mutation and timing of immune check point inhibitors (ICI) on local failure (LF). MATERIALS AND METHODS: 165 patients and 389 spinal segments were retrospectively reviewed from 2009 to 2021. Baseline patient characteristics, treatment and outcomes were abstracted. Primary endpoint was LF and secondary, overall survival (OS) and vertebral compression fracture (VCF). Multivariable analysis (MVA) evaluated factors predictive of LF and VCF. RESULTS: The median follow-up and OS were: 13.0 months (range, 0.5-95.3 months) and 18.4 months (95% CI 11.4-24.6). 52.1% were male and 76.4% had adenocarcinoma. Of the 389 segments, 30.3% harboured an EGFR mutation and 17.0% were PD-L1 ≥ 50%. The 24 months LF rate in PD-L1 ≥ 50% vs PD-L1 < 50% was 10.7% vs. 38.0%, and in EGFR-positive vs. negative was 18.1% vs. 30.0%. On MVA, PD-L1 status of ≥ 50% (HR 0.32, 95% CI 0.15-0.69, p = 0.004) significantly predicted for lower LF compared to PD-L1 < 50%. Lower LF trend was seen with ICI administration peri and post SBRT (HR 0.41, 95% CI 0.16-1.05, p = 0.062). On MVA, polymetastatic disease (HR 3.28, 95% CI 1.84-5.85, p < 0.0001) and ECOG ≥ 2 (HR 1.87, 95% CI 1.16-3.02, p = 0.011) significantly predicted for worse OS and absence of baseline VCF predicted for lower VCF rate (HR 0.20, 95% CI 0.10-0.39, p < 0.0001). CONCLUSION: We report a significant association of PD-L1 ≥ 50% status on improved LC rates from spine SBRT in NSCLC patients.

Chemical Exchange Saturation Transfer MRI for Differentiating Radiation Necrosis From Tumor Progression in Brain Metastasis-Application in a Clinical Setting.

BACKGROUND: High radiation doses of stereotactic radiosurgery (SRS) for brain metastases (BM) can increase the likelihood of radiation necrosis (RN). Advanced MRI sequences can improve the differentiation between RN and tumor progression (TP). PURPOSE: To use saturation transfer MRI methods including chemical exchange saturation transfer (CEST) and magnetization transfer (MT) to distinguish RN from TP. STUDY TYPE: Prospective cohort study. SUBJECTS: Seventy patients (median age 60; 73% females) with BM (75 lesions) post-SRS. FIELD STRENGTH/SEQUENCE: 3-T, CEST imaging using low/high-power (saturation B1  = 0.52 and 2.0 µT), quantitative MT imaging using B1  = 1.5, 3.0, and 5.0 µT, WAter Saturation Shift Referencing (WASSR), WAter Shift And B1 (WASABI), T1 , and T2 mapping. All used gradient echoes except T2 mapping (gradient and spin echo). ASSESSMENT: Voxel-wise metrics included: magnetization transfer ratio (MTR); apparent exchange-dependent relaxation (AREX); MTR asymmetry; normalized MT exchange rate and pool size product; direct water saturation peak width; and the observed T1 and T2 . Regions of interests (ROIs) were manually contoured on the post-Gd T1 w. The mean (of median ROI values) was compared between groups. Clinical outcomes were determined by clinical and radiologic follow-up or histopathology. STATISTICAL TESTS: t-Test, univariable and multivariable logistic regression, receiver operating characteristic, and area under the curve (AUC) with sensitivity/specificity values with the optimal cut point using the Youden index, Akaike information criterion (AIC), Cohen's d. P < 0.05 with Bonferroni correction was considered significant. RESULTS: Seven metrics showed significant differences between RN and TP. The high-power MTR showed the highest AUC of 0.88, followed by low-power MTR (AUC = 0.87). The combination of low-power CEST scans improved the separation compared to individual parameters (with an AIC of 70.3 for low-power MTR/AREX). Cohen's d effect size showed that the MTR provided the largest effect sizes among all metrics. DATA CONCLUSION: Significant differences between RN and TP were observed based on saturation transfer MRI. EVIDENCE LEVEL: 3 Technical Efficacy: Stage 2.

Patterns of treatment and outcomes of patients with brain-only metastatic breast cancer.

BACKGROUND: We characterized the risk factors and survival of metastatic breast cancer (MBC) patients with brain metastases (BrM) as the first and only site of disease in a large, retrospective cohort. METHODS: MBC patients treated for BrM with radiation at a quaternary institution between 2005 and 2019 were identified. MBC patients with BrM but without concurrent extracranial metastases (ECM) or leptomeningeal disease (LMD) were classified as brain-only. Factors associated with brain-only MBC, brain-specific progression free survival (bsPFS) and overall survival (OS) were investigated. RESULTS: A total of 691 patients with MBC and BrM were analyzed. Among them, 67 patients (9.7%, n = 67/691) presented with brain-only MBC without concurrent ECM/LMD. Within this subgroup, 40 patients (5.8%, n = 40/691) remained free of any ECM or LMD, while 17 patients (2.5%) developed LMD, and 10 patients (1.4%%) developed ECM with a median follow-up of 8 months (IQR 2-35). Patients with brain-only MBC were more likely to have a single BrM [OR 3.41 (1.62-7.19), p = 0.001] and either HER2+ [OR 3.3 (1.13-9.65), p = 0.03] or TNBC [OR 4.09 (1.42-11.74), p = 0.009] subtypes. Patients who presented with brain-only MBC also had significantly longer OS [HR 0.45, (0.22-0.86), p = 0.008] and a trend toward longer bsPFS [HR 0.67 (0.44-1.03), p = 0.05] compared to those with concurrent ECM/LMD. CONCLUSION: Patients with brain-only MBC had a longer bsPFS and OS than those with ECM. Patients with HER2+ and TNBC were more likely to have brain-only disease compared to those with HR+/HER2- MBC.

Stereotactic body radiotherapy for spine metastases: a review of 24 Gy in 2 daily fractions.

PURPOSE: Stereotactic body radiotherapy (SBRT) has proven to be a highly effective treatment for selected patients with spinal metastases. Randomized evidence shows improvements in complete pain response rates and local control with lower retreatment rates favoring SBRT, compared to conventional external beam radiotherapy (cEBRT). While there are several reported dose-fractionation schemes for spine SBRT, 24 Gy in 2 fractions has emerged with Level 1 evidence providing an excellent balance between minimizing treatment toxicity while respecting patient convenience and financial strain. METHODS: We provide an overview of the 24 Gy in 2 SBRT fraction regimen for spine metastases, which was developed at the University of Toronto and tested in an international Phase 2/3 randomized controlled trial. RESULTS: The literature summarizing global experience with 24 Gy in 2 SBRT fractions suggests 1-year local control rates ranging from 83-93.9%, and 1-year rates of vertebral compression fracture ranging from 5.4-22%. Reirradiation of spine metastases that failed prior cEBRT is also feasible with 24 Gy in 2 fractions, and 1-year local control rates range from 72-86%. Post-operative spine SBRT data are limited but do support the use of 24 Gy in 2 fractions with reported 1-year local control rates ranging from 70-84%. Typically, the rates of plexopathy, radiculopathy and myositis are under 5% in those series reporting mature follow up, with no cases of radiation myelopathy (RM) reported in the de novo setting when the spinal cord avoidance structure is limited to 17 Gy in 2 fractions. However, re-irradiation RM has been observed following 2 fraction SBRT. More recently, 2-fraction dose escalation with 28 Gy, with a higher dose constraint to the critical neural tissues, has been reported suggesting improved rates of local control. This regimen may be important in those patients with radioresistant histologies, high grade epidural disease, and/or paraspinal disease. CONCLUSION: The dose-fractionation of 24 Gy in 2 fractions is well-supported by published literature and is an ideal starting point for centers looking to establish a spine SBRT program.

Re-irradiation for recurrent high-grade glioma: an analysis of prognostic factors for survival and predictors of radiation necrosis.

PURPOSE: Recurrent high-grade glioma (rHGG) is a heterogeneous population, and the ideal patient selection for re-irradiation (re-RT) has yet to be established. This study aims to identify prognostic factors for rHGG patients treated with re-RT. METHODS: We retrospectively reviewed consecutive adults with rHGG who underwent re-RT from 2009 to 2020 from our institutional database. The primary objective was overall survival (OS). Secondary endpoints included prognostic factors for early death (< 6 months after re-RT) and predictors of radiation necrosis (RN). RESULTS: For the 79 patients identified, the median OS after re-RT was 9.9 months (95% CI 8.3-11.6). On multivariate analyses, re-resection at progression (HR 0.56, p = 0.027), interval from primary treatment to first progression ≥ 16.3 months (HR 0.61, p = 0.034), interval from primary treatment to re-RT ≥ 23.9 months (HR 0.35, p < 0.001), and re-RT PTV volume < 112 cc (HR 0.27, p < 0.001) were prognostic for improved OS. Patients who had unmethylated-MGMT tumours (OR 12.4, p = 0.034), ≥ 3 prior systemic treatment lines (OR 29.1, p = 0.022), interval to re-RT < 23.9 months (OR 9.0, p = 0.039), and re-RT PTV volume ≥ 112 cc (OR 17.8, p = 0.003) were more likely to die within 6 months of re-RT. The cumulative incidence of RN was 11.4% (95% CI 4.3-18.5) at 12 months. Concurrent bevacizumab use (HR < 0.001, p < 0.001) and cumulative equivalent dose in 2 Gy fractions (EQD2, α/ß = 2) < 99 Gy2 (HR < 0.001, p < 0.001) were independent protective factors against RN. Re-RT allowed for less corticosteroid dependency. Sixty-six percent of failures after re-RT were in-field. CONCLUSION: We observe favorable OS rates following re-RT and identified prognostic factors, including methylation status, that can assist in patient selection and clinical trial design. Concurrent use of bevacizumab mitigated the risk of RN.

Hypofractionated stereotactic radiosurgery (HSRS) as a salvage treatment for brain metastases failing prior stereotactic radiosurgery (SRS).

INTRODUCTION: Various treatment options exist to salvage stereotactic radiosurgery (SRS) failures for brain metastases, including repeat SRS and hypofractionated SRS (HSRS). Our objective was to report outcomes specific to salvage HSRS for brain metastases that failed prior HSRS/SRS. METHODS: Patients treated with HSRS to salvage local failures (LF) following initial HSRS/SRS, between July 2010 and April 2020, were retrospectively reviewed. The primary outcomes were the rates of LF, radiation necrosis (RN), and symptomatic radiation necrosis (SRN). Univariable (UVA) and multivariable (MVA) analyses using competing risk regression were performed to identify predictive factors for each endpoint. RESULTS: 120 Metastases in 91 patients were identified. The median clinical follow up was 13.4 months (range 1.1-111.1), and the median interval between SRS courses was 13.1 months (range 3.0-56.5). 115 metastases were salvaged with 20-35 Gy in 5 fractions and the remaining five with a total dose ranging from 20 to 24 Gy in 3-fractions. 67 targets (56%) were postoperative cavities. The median re-treatment target volume and biological effective dose (BED10) was 9.5 cc and 37.5 Gy, respectively. The 6- and 12- month LF rates were 18.9% and 27.7%, for RN 13% and 15.6%, and for SRN were 6.1% and 7.0%, respectively. MVA identified larger re-irradiation volume (hazard ratio [HR] 1.02, p = 0.04) and shorter interval between radiosurgery courses (HR 0.93, p < 0.001) as predictors of LF. Treatment of an intact target was associated with a higher risk of RN (HR 2.29, p = 0.04). CONCLUSION: Salvage HSRS results in high local control rates and toxicity rates that compare favorably to those single fraction SRS re-irradiation experiences reported in the literature.

Relationship between apparent diffusion coefficient and survival as a function of distance from gross tumor volume on radiation planning MRI in newly diagnosed glioblastoma.

PURPOSE: To investigate the changes in apparent diffusion coefficient (ADC) within incrementally-increased margins beyond the gross tumor volume (GTV) on post-operative radiation planning MRI and their prognostic utility in glioblastoma. METHODS: Radiation planning MRIs of adult patients with newly diagnosed glioblastoma from 2017 to 2020 were assessed. The ADC values were normalized to contralateral normal white matter (nADC). Using 1 mm isotropic incremental margin increases from the GTV, the nADC values were calculated at each increment. Age, ECOG performance status, extent of resection and MGMT promoter methylation status were obtained from medical records. Using univariate and multivariable Cox regression analysis, association of nADC to progression-free and overall survival (PFS, OS) was assessed at each increment. RESULTS: Seventy consecutive patients with mean age of 53.6 ± 10.3 years, were evaluated. The MGMT promoter was methylated in 31 (44.3%), unmethylated in 36 (51.6%) and unknown in 3 (4.3%) patients. 11 (16%) underwent biopsy, 41 (44%) subtotal resection and 18 (26%) gross total resection. For each 1 mm increase in distance from GTV, the nADC decreased by 0.16% (p < 0.0001). At 1-5 mm increment, the nADC was associated with OS (p < 0.01). From 6 to 11 mm increment the nADC was associated with OS with the p-value gradually increasing from 0.018 to 0.046. nADC was not associated with PFS. CONCLUSION: The nADC values at 1-11 mm increments from the GTV margin were associated with OS. Future prospective multicenter studies are needed to validate the findings and to pave the way for the utilization of ADC for margin reduction in radiation planning.

Upfront Small Bowel Resection for Small Bowel Neuroendocrine Tumors With Synchronous Metastases: A Propensity-score Matched Comparative Population-based Analysis.

OBJECTIVE: We examined the impact of upfront small bowel resection (USBR) for metastatic small bowel neuroendocrine (SB-NET) compared to nonoperative management (NOM) on long-term healthcare utilization and survival outcomes. SUMMARY OF BACKGROUND DATA: The role of early resection of the primary tumor in metastatic SB-NET remains controversial. Conflicting data exist regarding its clinical and survival benefits. METHODS: This is a population-based retrospective matched comparative cohort study of adults diagnosed with synchronous metastatic SB-NET between 2001 and 2017 in Ontario. USBR was defined as resection within 6 months of diagnosis. Primary outcomes were subsequent unplanned acute care admissions and small bowel-related surgery. Secondary outcome was overall survival. USBR and NOM patients were matched 2:1 using a propensity-score. We used time-to-event analyses with cumulative incidencefunctions and univariate Andersen-Gill regression for primary outcomes. E value methods assessed the potential for residual confounding. RESULTS: Of 1000 patients identified, 785 had USBR. The matched cohort included 348 patients with USBR and 174 with NOM. Patients with USBR had lower 3-year risk of subsequent admissions (72.6% vs 86.4%, P < 0.001) than those with NOM, with hazard ratio 0.72 (95% confidence interval 0.570.91). USBR was associated with lower risk of subsequent small bowel-related surgery (15.4% vs 40.3%, P < 0.001), with hazard ratio 0.44 (95% confidence interval 0.29-0.67). E -values indicated it was unlikely that the observed risk estimates could be explained by an unmeasured confounder. Sensitivity analysis excluding emergent resections to define USBR did not alter the results. CONCLUSIONS: USBR for SB-NETs in the presence of metastatic disease was associated with better patient-oriented outcomes of decreased subsequent admissions and interventions, compared to NOM. USBR should be considered for metastatic SB-NETs.

Stereotactic Ablative Radiotherapy for the Management of Liver Metastases from Neuroendocrine Neoplasms: A Preliminary Study.

INTRODUCTION: Liver metastases are common in patients with neuroendocrine neoplasms. The role of stereotactic ablative radiotherapy (SABR) is not well understood in this population. OBJECTIVE: The objective of this study was to evaluate the safety and efficacy of SABR in treating well-differentiated neuroendocrine liver metastases (WD-NELM). METHODS: A retrospective review of patients with WD-NELM treated with SABR was conducted between January 2015 and July 2019. Demographic, treatment, and clinical/radiographic follow-up data were abstracted. RECIST 1.1 criteria were applied to each individual target to evaluate the response to treatment. Local control (LC) and progression-free survival (PFS) were determined using the Kaplan-Meier methodology. Toxicity was reported according to the CTCAE v5.0. RESULTS: Twenty-five patients with a total of 53 liver metastases treated with SABR were identified. Most patients (68%) had midgut tumors, were grade 2 (80%), and had high-volume intrahepatic and/or extrahepatic disease (76%). The median number of liver metastases treated was 2, with a median size of 2.5 cm. The median radiation dose delivered was 50 Gy/5 fractions. The median follow-up was 14 months; 24 of the 25 patients were alive at the time of analysis. The objective response rate was 32%, with improvement or stability in 96% of lesions treated. The median time to best response was 9 months. The 1-year LC and PFS were 92 and 44%, respectively. No grade 3/4 acute or late toxicity was identified. CONCLUSIONS: Liver SABR is a safe and promising means of providing LC for WD-NELM. This treatment modality should be evaluated in selected patients in concert with strategies to manage systemic disease.

Trastuzumab emtansine increases the risk of stereotactic radiosurgery-induced radionecrosis in HER2 + breast cancer.

INTRODUCTION: In this study, we investigate factors associated with radionecrosis (RN) in HER2 + (human epidermal growth factor receptor 2) patients with brain metastases (BrM) treated with stereotactic radiosurgery (SRS). METHODS: Patients with HER2 + breast cancer BrM treated with SRS (2010-2020) were identified from an institutional database. The incidence of RN was determined per treated BrM according to serial imaging and/or histology. Factors associated with RN such as age, RT dose, BrM volume, and initiation of Trastuzumab Emtansine (T-DM1) were investigated with univariate and multivariable analyses (MVA). RESULTS: 67 HER2 + patients with 223 BrM were identified. 21 patients (31.3%) were treated with T-DM1 post-SRS, including 14 patients (20.9%) who received T-DM1 within 12 months of SRS. The median follow-up was 15.6 (interquartile range (IQR) 5.4-35.3) months. The overall probability of RN post-SRS was 21.6% (95% confidence interval (CI) 2.7-10.7), and the 1 and 2 year risk was 6.7% (95% CI 2.7-10.7) and 15.2% (95% CI 9.2-21.3). MVA identified T-DM1 treatment post-SRS (hazard ratio (HR) 2.5, 95% CI 1.2-5.3, p = 0.02) and equivalent dose in 2 Gy fractions (EQD2) > 90 Gy2 (HR 2.4, 95% CI 1.1-5.1, p = 0.02) as predictors of RN. Patients treated with T-DM1 and SRS had a 29.9% (95% CI 15.3-44.6%) probability of RN, with a 25.2% (95% CI 12.8-37.6%) risk at 1- and 2 years post-T-DM1. The majority of RN were symptomatic (71%), with a median time to RN of 4.8 months. CONCLUSION: T-DM1 exposure post-SRS was associated with a higher risk of RN among patients with HER2 + BrM.

Radiation myelopathy following stereotactic body radiation therapy for spine metastases.

PURPOSE: Stereotactic body radiation therapy (SBRT) is now considered a standard of care treatment option in the management of spine metastases. One of the most feared complications of spine SBRT is radiation myelopathy (RM). METHODS: We provided a narrative review of RM following spine SBRT based on review of the published literature, including data on spinal cord dose constraints associated with the risk of RM, strategies to mitigate the risk, and management options for RM. RESULTS: There are limited published data of cases of RM following spine SBRT with detailed spinal cord dosimetry. The HyTEC report provided recommendations for the point maximal dose (Dmax) for the spinal cord that is associated with a < 5% risk of RM for 1-5 fractions spine SBRT. In the setting of spine SBRT reirradiation after previous conventional external beam radiation therapy (cEBRT), factors associated with RM are: SBRT spinal cord Dmax, cumulative spinal cord Dmax, and the time interval between previous RT and SBRT reirradiation. There are various strategies to mitigate the risk of RM, including accurate delineation of the spinal cord (or thecal sac), strict adherence to the recommended spinal cord dose constraints, and robust treatment immobilisation set-up and delivery. Limited effective treatment options are available for patients who develop RM, and these include corticosteroids, hyperbaric oxygen, and bevacizumab; however, none have been supported by high quality evidence. CONCLUSION: RM is a rare but devastating complication following SBRT for spine metastases. There are strategies to minimise the risk of RM to ensure safe delivery of spine SBRT.

Inter-fraction dynamics during post-operative 5 fraction cavity hypofractionated stereotactic radiotherapy with a MR LINAC: a prospective serial imaging study.

PURPOSE/OBJECTIVE(S): This study examined changes in the clinical target volume (CTV) and associated clinical implications on a magnetic resonance imaging linear accelerator (MR LINAC) during hypofractionated stereotactic radiotherapy (HSRT) to resected brain metastases. In addition, the suitability of using T2/FLAIR (T2f) sequence to define CTV was explored by assessing contouring variability between gadolinium-enhanced T1 (T1c) and T2f sequences. MATERIALS/METHODS: Fifteen patients treated to either 27.5 or 30 Gy with five fraction HSRT were imaged with T1c and T2f sequences during treatment; T1c was acquired at planning (FxSim), and fraction 3 (Fx3), and T2f was acquired at FxSim and all five fractions. The CTV were contoured on all acquired images. Inter-fraction cavity dynamics and CTV contouring variability were quantified using absolute volume, Dice similarity coefficient (DSC), and Hausdorff distance (HD) metrics. RESULTS: The median CTV on T1c and T2f sequences at FxSim were 12.0cm3 (range, 1.2-30.1) and 10.2cm3 (range, 2.9-27.9), respectively. At Fx3, the median CTV decreased in both sequences to 9.3cm3 (range, 3.7-25.9) and 8.6cm3 (range, 3.3-22.5), translating to a median % relative reduction of - 11.4% on T1c (p = 0.009) and - 8.4% on T2f (p = 0.032). We observed a median % relative reduction in CTV between T1c and T2f at FxSim of - 6.0% (p = 0.040). The mean DSC was 0.85 ± 0.10, and the mean HD was 5.3 ± 2.7 mm when comparing CTV on T1c and T2f at FxSim. CONCLUSION: Statistically significant reductions in cavity CTV was observed during HSRT, supporting the use of MR image guided radiation therapy and treatment adaptation to mitigate toxicity. Significant CTV contouring variability was seen between T1c and T2f sequences. Trial registration NCT04075305 - August 30, 2019.

Predicting survival in patients with glioblastoma using MRI radiomic features extracted from radiation planning volumes.

BACKGROUND: Quantitative image analysis using pre-operative magnetic resonance imaging (MRI) has been able to predict survival in patients with glioblastoma (GBM). The study explored the role of postoperative radiation (RT) planning MRI-based radiomics to predict the outcomes, with features extracted from the gross tumor volume (GTV) and clinical target volume (CTV). METHODS: Patients with IDH-wildtype GBM treated with adjuvant RT having MRI as a part of RT planning process were included in the study. 546 features were extracted from each GTV and CTV. A LASSO Cox model was applied, and internal validation was performed using leave-one-out cross-validation with overall survival as endpoint. Cross-validated time-dependent area under curve (AUC) was constructed to test the efficacy of the radiomics model, and clinical features were used to generate a combined model. Analysis was done for the entire group and in individual surgical groups-gross total excision (GTR), subtotal resection (STR), and biopsy. RESULTS: 235 patients were included in the study with 57, 118, and 60 in the GTR, STR, and biopsy subgroup, respectively. Using the radiomics model, binary risk groups were feasible in the entire cohort (p < 0.01) and biopsy group (p = 0.04), but not in the other two surgical groups individually. The integrated AUC (iAUC) was 0.613 for radiomics-based classification in the biopsy subgroup, which improved to 0.632 with the inclusion of clinical features. CONCLUSION: Imaging features extracted from the GTV and CTV regions can lead to risk-stratification of GBM undergoing biopsy, while the utility in other individual subgroups needs to be further explored.

Gamma knife icon based hypofractionated stereotactic radiosurgery (GKI-HSRS) for brain metastases: impact of dose and volume.

OBJECTIVE: Gamma Knife Icon-based hypofractionated stereotactic radiosurgery (GKI-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the GKI stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control and adverse radiation effect (ARE) outcomes following 5 fraction GKI-HSRS for intact brain metastases. METHODS: Patients with intact brain metastases treated with 5-fraction GKI-HSRS were retrospectively reviewed. Survival, local control, and adverse radiation effect rates were determined. Univariable and multivariable regression (MVA) were performed on potential predictive factors. RESULTS: Two hundred and ninety-nine metastases in 146 patients were identified. The median clinical follow-up was 10.7 months (range 0.5-47.6). The median total dose and prescription isodose was 27.5 Gy (range, 20-27.5) in 5 daily fractions and 52% (range, 45-93), respectively. The median overall survival (OS) was 12.7 months, and the 1-year local failure rate was 15.2%. MVA identified a total dose of 27.5 Gy vs. ≤ 25 Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥ 4.5 cc (HR 7.29, p < 0.001) as a significant predictor of symptomatic ARE. CONCLUSION: Moderate total doses in 5 daily fractions of GKI-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE.

Proposing a quantitative MRI-based linear measurement framework for response assessment following stereotactic body radiation therapy in patients with spinal metastasis.

PURPOSE: To provide evidence towards a quantitative response assessment framework incorporating MRI-based linear measurements for spinal metastasis that predicts outcome following stereotactic body radiation therapy (SBRT). METHODS: Adult patients with de novo spinal metastases treated with SBRT between 2008 and 2018 were retrospectively assessed. The metastatic lesions involving the pedicles, articular processes, lamina, transverse process, spinous process and vertebral body at leach level were measured separately using linear measurements on pre- and all post-SBRT MRIs. The outcome was segment-specific progression (SSP) using SPINO guidelines which was dated to the first clinical documentation of progression, or the date of the associated MRI if imaging was the reason for progression. Random forest analysis for variable selection and recursive partitioning analysis for SSP probability prediction were used. RESULTS: Five Hundred Ninety-three spinal levels (323 patients) from 4081 MRIs were evaluated. The appearance of new T1 hypointensity and increase in Bilsky grade had an odds ratio (OR) of 33.5 and 15.5 for SSP, respectively. Compared to baseline, an increase of > 3 mm in any lesion dimension, combined with a 1.67-fold increase in area, had an OR of 4.6 for SSP. The sensitivity, specificity, positive predictive value, negative predictive value, balanced accuracy and area under the curve of the training model were 96.7%, 89.6%, 28.6%, 99.8%, 93.2% and 0.905 and of the test model were 91.3%, 89.3%, 27.1% 99.6%, 90.3% and 0.933, respectively. CONCLUSION: With further refinement and validation in prospective multicentre studies, MRI-based linear measurements can help predict response assessment in SBRT-treated spinal metastases.

Incidence of psychiatric illness in patients with neuroendocrine tumors: a comparative population-based analysis.

PURPOSE: Diversion of tryptophan to tumoral hormonal production has been suggested to result in psychiatric illnesses in neuroendocrine tumors (NET). We measured the occurrence of psychiatric illness after NET diagnosis and compare it to colon cancer (CC). METHODS: We conducted a population-based retrospective cohort study. Adults with NET were matched 1:1 to CC (2000-2019). Psychiatric illness was defined by mental health diagnoses and mental health care use after a cancer diagnosis, categorized as severe, other, and none. Cumulative incidence functions accounted for death as a competing risk. RESULTS: A total of 11,223 NETs were matched to CC controls. Five-year cumulative incidences of severe psychiatric illness for NETs vs. CC was 7.7% (95%CI 7.2-8.2%) vs 7.6% (95%CI 7.2-8.2%) (p = 0.50), and that of other psychiatric illness was 32.9% (95%CI 32.0-33.9%) vs 31.6% (95%CI 30.8-32.6%) (p = 0.005). In small bowel and lung NETs, 5-year cumulative incidences of severe (8.1% [95%CI 7.3-8.9%] vs. 7.0% [95%CI 6.3-7.8%]; p = 0.01) and other psychiatric illness (34.7% [95%CI 33.3-36.1%] vs. 31.1% [95%CI 29.7-32.5%]; p < 0.01) were higher than for matched CC. The same was observed for serotonin-producing NETs for both severe (7.9% [95%CI 6.5-9.4%] vs. 6.8% [95%CI 5.5-8.2%]; p = 0.02) and other psychiatric illness (35.4% [95%CI 32.8-38.1%] vs. 31.9% [95%CI 29.3-34.4%]; p = 0.02). CONCLUSIONS: In all NETs, there was no difference observed in the incidence of psychiatric illness compared to CC. For sub-groups of small bowel and lung NETs and of serotonin-producing NETs, the incidence of psychiatric illness was higher than for CC. These data suggest a signal towards a relationship between those sub-groups of NETs and psychiatric illness.

Stereotactic body radiotherapy versus conventional external beam radiotherapy in patients with painful spinal metastases: an open-label, multicentre, randomised, controlled, phase 2/3 trial.

BACKGROUND: Conventional external beam radiotherapy is the standard palliative treatment for spinal metastases; however, complete response rates for pain are as low as 10-20%. Stereotactic body radiotherapy delivers high-dose, ablative radiotherapy. We aimed to compare complete response rates for pain after stereotactic body radiotherapy or conventional external beam radiotherapy in patients with painful spinal metastasis. METHODS: This open-label, multicentre, randomised, controlled, phase 2/3 trial was done at 13 hospitals in Canada and five hospitals in Australia. Patients were eligible if they were aged 18 years and older, and had painful (defined as ≥2 points with the Brief Pain Inventory) MRI-confirmed spinal metastasis, no more than three consecutive vertebral segments to be included in the treatment volume, an Eastern Cooperative Oncology Group performance status of 0-2, a Spinal Instability Neoplasia Score of less than 12, and no neurologically symptomatic spinal cord or cauda equina compression. Patients were randomly assigned (1:1) with a web-based, computer-generated allocation sequence to receive either stereotactic body radiotherapy at a dose of 24 Gy in two daily fractions or conventional external beam radiotherapy at a dose of 20 Gy in five daily fractions using standard techniques. Treatment assignment was done centrally by use of a minimisation method to achieve balance for the stratification factors of radiosensitivity, the presence or absence of mass-type tumour (extraosseous or epidural disease extension, or both) on imaging, and centre. The primary endpoint was the proportion of patients with a complete response for pain at 3 months after radiotherapy. The primary endpoint was analysed in the intention-to-treat population and all safety and quality assurance analyses were done in the as-treated population (ie, all patients who received at least one fraction of radiotherapy). The trial is registered with ClinicalTrials.gov, NCT02512965. FINDINGS: Between Jan 4, 2016, and Sept 27, 2019, 229 patients were enrolled and randomly assigned to receive conventional external beam radiotherapy (n=115) or stereotactic body radiotherapy (n=114). All 229 patients were included in the intention-to-treat analysis. The median follow-up was 6·7 months (IQR 6·3-6·9). At 3 months, 40 (35%) of 114 patients in the stereotactic body radiotherapy group, and 16 (14%) of 115 patients in the conventional external beam radiotherapy group had a complete response for pain (risk ratio 1·33, 95% CI 1·14-1·55; p=0·0002). This significant difference was maintained in multivariable-adjusted analyses (odds ratio 3·47, 95% CI 1·77-6·80; p=0·0003). The most common grade 3-4 adverse event was grade 3 pain (five [4%] of 115 patients in the conventional external beam radiotherapy group vs five (5%) of 110 patients in the stereotactic body radiotherapy group). No treatment-related deaths were observed. INTERPRETATION: Stereotactic body radiotherapy at a dose of 24 Gy in two daily fractions was superior to conventional external beam radiotherapy at a dose of 20 Gy in five daily fractions in improving the complete response rate for pain. These results suggest that use of conformal, image-guided, stereotactically dose-escalated radiotherapy is appropriate in the palliative setting for symptom control for selected patients with painful spinal metastases, and an increased awareness of the need for specialised and multidisciplinary involvement in the delivery of end-of-life care is needed. FUNDING: Canadian Cancer Society and the Australian National Health and Medical Research Council.

Risk of Cancer-Specific Death for Patients Diagnosed With Neuroendocrine Tumors: A Population-Based Analysis.

BACKGROUND: Although patients with neuroendocrine tumors (NETs) are known to have prolonged overall survival, the contribution of cancer-specific and noncancer deaths is undefined. This study examined cancer-specific and noncancer death after NET diagnosis. METHODS: We conducted a population-based retrospective cohort study of adult patients with NETs from 2001 through 2015. Using competing risks methods, we estimated the cumulative incidence of cancer-specific and noncancer death and stratified by primary NET site and metastatic status. Subdistribution hazard models examined prognostic factors. RESULTS: Among 8,607 included patients, median follow-up was 42 months (interquartile range, 17-82). Risk of cancer-specific death was higher than that of noncancer death, at 27.3% (95% CI, 26.3%-28.4%) and 5.6% (95% CI, 5.1%-6.1%), respectively, at 5 years. Cancer-specific deaths largely exceeded noncancer deaths in synchronous and metachronous metastatic NETs. Patterns varied by primary tumor site, with highest risks of cancer-specific death in bronchopulmonary and pancreatic NETs. For nonmetastatic gastric, small intestine, colonic, and rectal NETs, the risk of noncancer death exceeded that of cancer-specific deaths. Advancing age, higher material deprivation, and metastases were independently associated with higher hazards, and female sex and high comorbidity burden with lower hazards of cancer-specific death. CONCLUSIONS: Among all NETs, the risk of dying of cancer was higher than that of dying of other causes. Heterogeneity exists by primary NET site. Some patients with nonmetastatic NETs are more likely to die of noncancer causes than of cancer causes. This information is important for counseling, decision-making, and design of future trials. Cancer-specific mortality should be included in outcomes when assessing treatment strategies.

MRI radiomics to differentiate between low grade glioma and glioblastoma peritumoral region.

BACKGROUND: The peritumoral region (PTR) of glioblastoma (GBM) appears as a T2W-hyperintensity and is composed of microscopic tumor and edema. Infiltrative low grade glioma (LGG) comprises tumor cells that seem similar to GBM PTR on MRI. The work here explored if a radiomics-based approach can distinguish between the two groups (tumor and edema versus tumor alone). METHODS: Patients with GBM and LGG imaged using a 1.5 T MRI were included in the study. Image data from cases of GBM PTR, and LGG were manually segmented guided by T2W hyperintensity. A set of 91 first-order and texture features were determined from each of T1W-contrast, and T2W-FLAIR, diffusion-weighted imaging sequences. Applying filtration techniques, a total of 3822 features were obtained. Different feature reduction techniques were employed, and a subsequent model was constructed using four machine learning classifiers. Leave-one-out cross-validation was used to assess classifier performance. RESULTS: The analysis included 42 GBM and 36 LGG. The best performance was obtained using AdaBoost classifier using all the features with a sensitivity, specificity, accuracy, and area of curve (AUC) of 91%, 86%, 89%, and 0.96, respectively. Amongst the feature selection techniques, the recursive feature elimination technique had the best results, with an AUC ranging from 0.87 to 0.92. Evaluation with the F-test resulted in the most consistent feature selection with 3 T1W-contrast texture features chosen in over 90% of instances. CONCLUSIONS: Quantitative analysis of conventional MRI sequences can effectively demarcate GBM PTR from LGG, which is otherwise indistinguishable on visual estimation.