Exploring the Evolving Landscape of Stereotactic Body Radiation Therapy in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) carries significant morbidity and mortality. Management of the HCC requires a multidisciplinary approach. Surgical resection and liver transplantation are the gold standard options for the appropriate settings. Stereotactic body radiation therapy (SBRT) has emerged as a promising treatment modality in managing HCC; its use is more studied and well-established in advanced HCC (aHCC). Current clinical guidelines universally endorse SBRT as a viable alternative to radiofrequency ablation (RFA), transarterial chemoembolisation (TACE), and transarterial radioembolisation (TARE), a recommendation substantiated by literature demonstrating comparable efficacy among these modalities. In early-stage HCC, SBRT primarily manages unresectable tumours unsuitable for ablative procedures such as microwave ablation and RFA. SBRT has been incorporated as a modality to downstage tumours or as a bridge to transplant. In the case of intermediate or advanced HCC, SBRT offers excellent results either as a single modality or adjunct to other locoregional modalities such as TACE/TARE. Recent data from late-stage HCC patients illustrate the effectiveness of SBRT in achieving local tumour control while minimising damage to surrounding healthy liver tissue. It has promising local control of approximately 80-90% in managing HCC. Additional prospective data comparing the efficacy of SBRT with the first-line recommended therapies such as RFA, TACE, and surgery are essential. The standard of care for patients with advanced/metastatic disease is systemic therapy (immunotherapy/tyrosine kinase inhibitors). SBRT, in combination with immune-checkpoint inhibitors, has an immune-modulatory effect that results in a synergistic effect. Recent findings indicate that the combination of immunotherapy and SBRT in HCC is well-tolerated and exhibits synergistic effects. Further exploration of diverse immunotherapy and radiotherapy strategies is essential to identify the appropriate time for combination treatments and to optimise dose and fraction regimens. Prospective, randomised studies are imperative to establish SBRT as the primary treatment for HCC.

Separation surgery for metastatic spine tumors: How less became more.

Metastatic epidural spinal cord compression (MESCC) is an increasingly common clinical entity in cancer patients and is associated with significant morbidity and neurologic sequalae. Management of MESCC has undergone many significant paradigms shifts over the past 50 years and was at times managed exclusively with either surgery or radiation. Historically, aggressive surgical techniques to achieve en bloc or intralesional gross tumor resections were pursued but were associated with significant morbidity and poor tumor control rates when combined with conventional external beam radiation. However, improvements in radiation treatment delivery in the form of stereotactic body radiation therapy have allowed for the safe delivery of high-dose conformal photon beam radiation providing histology-independent ablative responses. This shifted the goals of surgery away from maximal tumor resection toward simple spinal cord decompression with reconstitution of the thecal to create a tumor target volume capable of being irradiated within the constraints of spinal cord tolerance. This new approach of creating space between the thecal sac and the tumor was termed separation surgery and when combined with postoperative SBRT, it is referred to as hybrid therapy. Herein, we will describe the evolution of the management of MESCC, the technique of separation surgery and its outcomes, and finish with an illustrative case example.

Predictors of brain metastases in patients with oligometastatic solid tumours treated with stereotactic body radiation therapy.

PURPOSE: In patients with oligometastatic disease (OMD) treated with stereotactic body radiation therapy (SBRT), those who develop brain metastases (BrM) may have poor outcomes. We aimed to investigate variables associated with BrM development in this population. METHODS: Patients with ≤ 5 extracranial metastases from solid tumors treated with SBRT from 2008 to 2016 at Sunnybrook Odette Cancer Centre were included. We investigated the association between covariates and CIBrM (cumulative incidence of BrM) using Fine-Gray analysis, and progression-free survival (PFS) and overall survival (OS) using Cox regression. We investigated the association between extracranial progression and CIBrM using time-based conditional analysis. RESULTS: Among 404 patients, the most common primary sites were lung, colorectal, prostate, breast and kidney. Median follow-up was 49 months. Median PFS was 25 months. Median OS was 70 months. 58 patients developed BrM, and 5-year CIBrM was 16%. On multivariable analysis, number of extracranial metastases, location of metastases, total planning target volume (PTV), and time from primary diagnosis to OMD were not associated with CIBrM, although several of these variables were associated with extracranial PFS and OS. Primary site was associated with CIBrM, with colorectal and prostate cancer associated with lower CIBrM compared to lung cancer. Widespread extracranial progression (≥ 5 sites) within 24, 36, 48 and 60 months of OMD diagnosis was independently associated with higher CIBrM. CONCLUSION: In patients with OMD treated with SBRT, baseline variables related to extracranial disease burden and distribution were not associated with BrM development, while primary site and widespread extracranial progression were associated with BrM development.

Optimization of image reconstruction technique for respiratory-gated lung stereotactic body radiotherapy treatment planning using four-dimensional CT: a phantom study.

Patient respiration is characterized by respiratory parameters, such as cycle, amplitude, and baseline drift. In treatment planning using four-dimensional computed tomography (4DCT) images, the target dose may be affected by variations in image reconstruction techniques and respiratory parameters. This study aimed to optimize 4DCT image reconstruction techniques for the treatment planning of lung stereotactic body radiotherapy (SBRT) based on respiratory parameters using respiratory motion phantom. We quantified respiratory parameters using 30 respiratory motion datasets. The 4DCT images were acquired, and the phase- and amplitude-based reconstruction images (RI) were created. The target dose was calculated based on these reconstructed images. Statistical analysis was performed using Pearson's correlation coefficient (r) to determine the relationship between respiratory parameters and target dose in each reconstructed technique and respiratory region. In the inhalation region of phase-based RI, r of the target dose and baseline drift was -0.52. In particular, the target dose was significantly reduced for respiratory parameters with a baseline drift of 0.8 mm/s and above. No other respiratory parameters or respiratory regions were significantly correlated with target dose in phase-based RI. In amplitude-based RI, there were no significant differences in the correlation between all respiratory parameters and target dose in the exhalation or inhalation regions. These results showed that the target dose of the amplitude-based RI did not depend on changes in respiratory parameters or respiratory regions, compared to the phase-based RI. However, it is possible to guarantee the target dose by considering respiratory parameters during the inhalation region of the phase-based RI.

The Potential and Challenges of Proton FLASH in Head and Neck Cancer Reirradiation.

Ultrahigh-dose-rate therapy, also known as FLASH radiotherapy (RT), is an emerging technique that is garnering significant interest in cancer treatment due to its potential to revolutionize therapy. This method can achieve comparable tumor control to conventional-dose-rate RT while offering the enhanced protection of normal tissue through the FLASH-sparing effect. This innovative technique has demonstrated promising results in preclinical studies involving animals and cell lines. Particularly noteworthy is its potential application in treating head and neck (HN) cancers, especially in patients with challenging recurrent tumors and reirradiation cases, where the toxicity rates with conventional radiotherapy are high. Such applications aim to enhance tumor control while minimizing side effects and preserving patients' quality of life. In comparison to electron or photon FLASH modalities, proton therapy has demonstrated superior dosimetric and delivery characteristics and is a safe and effective FLASH treatment for human malignancies. Compared to the transmission proton FLASH, single-energy Bragg peak FLASH is a novel delivery method that allows highly conformal doses to targets and minimal radiation doses to crucial OARs. Proton Bragg peak FLASH for HN cancer has still not been well studied. This review highlights the significance of proton FLASH in enhancing cancer therapy by examining the advantages and challenges of using it for HN cancer reirradiation.

Racial/ethnic disparities in curative-intent treatment for early-stage non-small cell lung cancer patients among heterogeneous Black populations: US-born Black, Afro-Haitian, West Indian Black, and Hispanic Black.

BACKGROUND: Heterogeneous Black populations encounter significant obstacles in accessing cancer care, yet research on lung cancer treatment disparities remains limited. This study investigates whether the disparity in receiving curative-intent treatment (curative-intent surgery and/or stereotactic body radiation therapy [SBRT]) for early-stage non-small cell lung cancer (NSCLC) between non-Hispanic Whites (NHWs) and total Blacks extends to diverse Black populations, including US-born, Afro-Haitian, West Indian Black, and Hispanic Black individuals. METHODS: This cross-sectional study included all Florida cancer registry early-stage NSCLC cases 2005-2017, linked to individual-level discharge data containing comorbidity and specific treatment details (surgery and/or SBRT). Multivariable logistic regression assessed the association between race/ethnicity and the receipt of curative-intent treatment, while accounting for sociodemographic factors (poverty, age, insurance, and smoking status) and clinical variables. RESULTS: Among 55,655 early-stage NSCLC patients, 71.1% received curative-intent treatment: 72.1% NHW and 59.7% Black (non-Hispanic and Hispanic) individuals. Black patients had 35% lower odds (ORadj, 0.65; 95% CI, 0.59-0.70) of receiving curative-intent treatment compared to NHW patients. ORs varied from 0.57 (95% CI, 0.59-0.70) for Hispanic Black to 0.76 (95% CI, 0.56-1.02) for West Indian Black. Remarkably, Black-White disparities persisted despite the availability of curative treatment options (SBRT) for both high Charlson Comorbidity Index (CCI) observed among US-born Blacks and surgery for low CCI patients among all other Black subgroups. CONCLUSIONS: Pronounced disparities in accessing curative-intent treatments for early-stage NSCLC were evident across all Black subgroups, regardless of treatment availability and comorbidity profile. These findings underscore the need to address Black heterogeneity and prompt further research to rectify treatment disparities in early-stage NSCLC.

Dosimetric comparison of gamma knife and linear accelerator (VMAT and IMRT) plans of SBRT of Lung tumours.

This study evaluates dosimetric differences in Stereotactic Body Radiation Therapy (SBRT) for lung tumors using plans of Gamma Knife, and Volumetric Modulated Arc Therapy (VMAT), Intensity-Modulated Radiation Therapy (IMRT) plans based on Linear Accelerator, aiming to inform the reader of appropriate treatment strategy selection. Ten patients with 23 lung tumor lesions treated with SBRT at Zhongshan Hospital of Dalian University were analyzed. Plans of Gamma Knife, and VMAT, IMRT plans based on Linear Accelerator were created for each lesion, totaling 18 plans per type. Lesions were treated with 30-50 Gy in 5-10 fractions. Dosimetric parameters, including gradient index (GI), heterogeneity index (HI), conformity index (CI), and doses to the plan target volumes (PTVs), the gross tumor volumes (GTVs) and organs at risk (OARs) were compared. Plans of Gamma Knife showed superior HI and GI, higher PTV and GTV doses, and reduced doses to the ipsilateral and contralateral lungs, esophagus, spinal cord, and heart compared to VMAT and IMRT plans (p < 0.05). However, Plans of Gamma Knife required longer delivery times. When comparing VMAT and IMRT plans, VMAT plans had shorter delivery times than IMRT plans, but required more monitor units (MUs). Additionally, IMRT plans delivered a lower mean dose to the ipsilateral lung compared to VMAT plans. Gamma Knife SBRT plans achieves steeper dose falloff and minimizes radiation to normal lung tissue compared to VMAT and IMRT plans, but with longer delivery times. VMAT and IMRT plans displayed similar dose distributions for lung SBRT.

Stereotactic body radiotherapy alone versus stereotactic body radiotherapy after incomplete transarterial therapy for hepatocellular carcinoma.

INTRODUCTION: We investigated the clinical outcomes of stereotactic body radiation therapy (SBRT) alone versus SBRT after incomplete transarterial chemoembolization (TACE) for a single recurrent hepatocellular carcinoma (HCC) smaller than 5 cm. METHODS: We retrospectively reviewed the medical records of patients who underwent SBRT for a single recurrent HCC ≤5 cm, without vascular invasion or extrahepatic metastasis. Patients were divided into the SBRT-alone group and the TACE-SBRT group. The primary outcome was the local control (LC) rate, and secondary outcomes were survivals and treatment-related toxicities. We additionally conducted a propensity score matching (PSM) analysis. RESULTS: A total of 477 patients were available for analysis. Among them, 54 patients received SBRT without prior treatment to the target lesion (SBRT-alone group), whereas 423 patients received SBRT for viable HCC after TACE (TACE-SBRT group). The 3-year LC rates did not differ between the two groups (SBRT-alone group, 88.6% vs. TACE-SBRT group, 89.6%, P = 0.918). The 3-year rates of overall survival, out-of-field intrahepatic recurrence-free survival and recurrence-free survival were also not significantly different (P = 0.479, 0.290 and 0.273, respectively). Even after PSM, LC and survival rates at 3 years were not significantly different. CONCLUSION: SBRT alone demonstrated comparable local control and survival outcomes to SBRT following incomplete TACE. SBRT alone may be considered an alternative treatment option for a single recurrent HCC smaller than 5 cm when curative treatments or TACE are not feasible.

Confronting Complexity: Stereotactic Body Radiation Therapy for Localized Lung Cancer with a Pacemaker.

Introduction: Lung cancer management in patients with pacemakers presents unique challenges. This report examines the utilization of stereotactic body radiation therapy (SBRT) in such a patient population. Case Presentation: A 75-year-old former smoker with a dual-chamber pacemaker presented with inoperable lung adenocarcinoma. SBRT (48 Gy in 4 fractions) was chosen following multidisciplinary consultation and thorough pretreatment evaluation by a rhythmologist to assess pacemaker integrity. Continuous cardiac monitoring during SBRT detected no arrhythmias. Adjuvant therapy consisted of radiotherapy alone due to the patient's health status and limited evidence supporting chemotherapy in this context. At the 18-month follow-up, no cancer recurrence was observed, and regular device checks confirmed pacemaker integrity. Conclusion: This case demonstrates the successful management of inoperable lung adenocarcinoma with SBRT in a patient with a pacemaker. It underscores the significance of interdisciplinary cooperation and careful patient assessment to optimize treatment outcomes in this challenging clinical scenario.

Integrating IL-12 mRNA nanotechnology with SBRT eliminates T cell exhaustion in preclinical models of pancreatic cancer.

Pronounced T cell exhaustion characterizes immunosuppressive tumors, with the tumor microenvironment (TME) employing multiple mechanisms to elicit this suppression. Traditional immunotherapies, such as immune checkpoint blockade, often fail due to their focus primarily on T cells. To overcome this, we utilized a proinflammatory cytokine, interleukin (IL)-12, that re-wires the immunosuppressive TME by inducing T cell effector function while also repolarizing immunosuppressive myeloid cells. Due to toxicities observed with systemic administration of this cytokine, we utilized lipid nanoparticles encapsulating mRNA encoding IL-12 for intratumoral injection. This strategy has been proven safe and tolerable in early clinical trials for solid malignancies. We report an unprecedented loss of exhausted T cells and the emergence of an activated phenotype in murine pancreatic ductal adenocarcinoma (PDAC) treated with stereotactic body radiation therapy (SBRT) and IL-12mRNA. Our mechanistic findings reveal that each treatment modality contributes to the T cell response differently, with SBRT expanding the T cell receptor repertoire and IL-12mRNA promoting robust T cell proliferation and effector status. This distinctive T cell signature mediated marked growth reductions and long-term survival in local and metastatic PDAC models. This is the first study of its kind combining SBRT with IL-12mRNA and provides a promising new approach for treating this aggressive malignancy.

Sharing Mono-Institutional Experience of Treating Pancreatic Cancer with Stereotactic Body Radiation Therapy (SBRT).

BACKGROUND: Stereotactic body radiotherapy (SBRT) is an evolving treatment for the local management of pancreatic cancer (PC). The main purpose of this study is to report our initial experience in terms of local control (LC) and toxicity for PC patients treated with SBRT. METHODS: We conducted a retrospective review of patients treated with SBRT using abdominal compression (AC) or an end-expiratory breath-holding (EEBH) technique. The median prescribed dose was 35 Gy, delivered in five fractions. Toxicities were recorded using Common Terminology Criteria for Adverse Events (CTCAE) v5.0, and survival was estimated using the Kaplan-Meier method. RESULTS: From 2017 to 2023, 17 PC patients were offered SBRT. Their median age was 69 years. The median follow-up from the date of diagnosis was 22.37 months. The overall survival (OS) was 94% at 1 year and 60.9% at 2 years. The progression-free survival (PFS) was 63.1% at 6 months and 56.1% at 9 months. The median OS was 26.3 months, and the median PFS was 20.6 months. The 6-month and 1-year LC rates were 71% and 50.8%, respectively. CONCLUSION: We are successful in implementing the SBRT program at our centre. SBRT appears to be a promising treatment option for achieving LC with limited acute toxicities.

Stereotactic body radiotherapy is an alternative to radiofrequency ablation for single HCC ≤5.0 cm.

Background & Aims: Radiation therapy has been refined with increasing evidence of the benefits of stereotactic body radiation therapy (SBRT) in treating hepatocellular carcinoma (HCC). In this study, we aimed to evaluate whether SBRT could serve as an alternative to radiofrequency ablation (RFA) for small HCC with a single lesion ≤5.0 cm. Methods: Patients with a single HCC lesion ≤5.0 cm who received RFA or SBRT were included. Cumulative local/distant recurrence rate, progression-free survival, overall survival, adverse events and subsequent treatments after recurrence were analyzed. Results: A total of 288 patients receiving RFA (n = 166) or SBRT (n = 122) were enrolled. The baseline characteristics between the two groups were comparable. The cumulative local recurrence rate in the SBRT group was significantly lower than that in the RFA group (hazard ratio [HR] 0.30, 95% CI 0.16-0.57, p <0.001), especially for patients with tumours >2.0 cm (HR 0.20, 95% CI 0.08-0.50, p <0.001) or adjacent to major vessels (HR 0.29, 95% CI 0.13-0.66, p <0.001). Cumulative distant recurrence rate, progression-free survival and overall survival were not significantly different between the two groups (all p >0.050). Adverse events were mild and easily reversible. However, more patients in the SBRT group suffered from Child-Pugh score and total bilirubin increases. More treatment options after recurrence or progression might be available for patients in the RFA group compared to those in the SBRT group (p <0.001). Conclusions: Both RFA and SBRT were effective and safe for HCC with a single lesion ≤5.0 cm. SBRT could be an alternative treatment to RFA, especially for tumours >2.0 cm or adjacent to major vessels. Impact and implications: Stereotactic body radiation therapy (SBRT) may be used as an alternative treatment to thermal ablation for patients with BCLC stage A hepatocellular carcinoma (HCC) who are not candidates for surgical resection, including those with tumours >3 cm and those with 1 to 3 tumours. This study focused on HCC patients with a specific tumour burden, namely a single lesion ≤5.0 cm, demonstrating that SBRT could be an effective and safe alternative to radiofrequency ablation (RFA), especially for those with tumours >2.0 cm or adjacent to major vessels. The findings of this study provided robust empirical evidence supporting the utilization of SBRT in treating small HCC, while also establishing a solid foundation for future prospective clinical investigations.

Development and validation of a prognostic nomogram in patients aged ≥65 years with stage I-II non-small cell lung cancer treated with stereotactic body radiotherapy.

INTRODUCTION: This study aims to discern the efficacy and toxicity of stereotactic body radiotherapy (SBRT) in older adults with stage I-II non-small cell lung cancer (NSCLC) and establish a prognostic nomogram for these patients. MATERIALS AND METHODS: One hundred forty-two patients (aged ≥65 years) with clinically-confirmed stage I-II NSCLC treated with SBRT from 2009 to 2020 were enrolled in the study. Primary end points included overall survival (OS), progression free survival (PFS), cumulative incidences of local failure (LF), regional failure (RF), distant failure (DF), and toxicity. A nomogram for OS was developed and validated internally using one thousand bootstrap resamplings. RESULTS: The median times to LF, RF, and DF were 22.1 months, 26.9 months and 24.1 months, respectively. The 1-, 3-, and 5-year PFS rates from the start of SBRT were 79.4 %, 53.1 %, and 38.9 %, respectively. Performance status, pre-SBRT platelet to lymphocyte ratio (PLR), and planning tumor volume (PTV) were predictive of PFS. The 1-, 3-, and 5-year OS rates from the start of SBRT were 90.8 %, 67.9 % and 47.6 %, respectively. In multivariate analysis, good performance status, a low level of pre-SBRT PLR, and small tumor size were associated with better prognosis, all of which were included in the nomogram. The model showed optimal discrimination, with a C-index of 0.651 and good calibration. The most common adverse reactions were grade 1-2, such as anemia, cough, and fatigue. DISCUSSION: SBRT is a reasonable treatment modality for early-stage NSCLC in older adults. It achieved good survival outcomes and low toxicity. The proposed nomogram may be able to estimate individual outcomes for these patients.

Adrenal Insufficiency following Stereotactic Ablative Radiotherapy (SAbR) of Adrenal Gland Metastases.

BACKGROUND: Adrenal metastases are often treated with stereotactic ablative radiation (SAbR). We aimed to assess the incidence, timing, and factors associated with the development of primary adrenal insufficiency (PAI) following SAbR. METHODS: A retrospective cohort study comprised 66 consecutive patients (73% men, median age 61 years) who underwent SAbR for adrenal metastasis. RESULTS: The series encompassed metastases from renal cell carcinoma (41%), lung tumors (38%), colorectal adenocarcinoma (9%), melanoma (5%), and others (7%). Median follow-up was 17 months from SAbR. Nine (14%) patients developed PAI at a median of 4.3 months (range, 0.7-20.2). The incidence of PAI was 44% in patients with prior adrenalectomy receiving unilateral SAbR, 44% with bilateral SAbR, 2% with unaffected contralateral gland, and 0% with bilateral metastases treated with unilateral SAbR. PAI was associated with prior adrenalectomy (odds ratio [OR] 32) and bilateral SAbR (OR 8.2), but not age, sex, metastasis size, or biological effective dose. Post-SAbR 6-month and 1-year local control rates were 82% and 75%, respectively. CONCLUSIONS: Patients undergoing SAbR for adrenal metastasis are at high risk of developing PAI. PAI is associated with bilateral SAbR and contralateral adrenalectomy. PAI is unlikely with a remaining unaffected adrenal gland or in the setting of bilateral adrenal metastases with unilateral SAbR.

Oligometastatic Urothelial Cancer and Stereotactic Body Radiotherapy: A Systematic Review and an Updated Insight of Current Evidence and Future Directions.

BACKGROUND: Stereotactic body radiation therapy (SBRT) is the most commonly used metastasis-directed therapy (MDT) for oligometastatic urothelial carcinoma (omUC). Despite efforts in defining this disease entity, open questions remain concerning the role of MDT and the use of biomarkers, imaging, and its combination with systemic therapies. The aim of the present systematic review is to provide an updated overview of the current clinical evidence on SBRT for omUC in terms of survival and local control benefits. We also aim to provide updates on controversial areas and future directions in this emerging field. METHODS: With a systematic approach, following PRISMA recommendations, we searched two databases to identify and select articles published up until March 2024 reporting the use of SBRT for omUC with or without concomitant systemic therapies. Prospective randomized or non-randomized studies as well as retrospective studies were included. RESULTS: Eight studies were selected for data extraction and 293 omUC patients treated with SBRT were collectively analyzed. In metachronous omUC patients, SBRT delivered with ablative doses (BED10 ≥ 78 Gy) was associated with a 2-year overall survival (OS) rate of 50.7% (95% CI 35.1-64.4%). The use of sub-ablative SBRT doses (BED10 = 43.2 Gy) in combination with immunotherapy did not demonstrate significant clinical outcome improvement in two prospective studies. The overall tolerance was good, with only one study reporting toxicity of grade 3 in up to 18% of the patients treated with SBRT in combination with immunotherapy. CONCLUSIONS: SBRT is an effective and widely available MDT option in omUC, although this is based on a limited number of studies. Despite the attempt to use SBRT as an immune response trigger in combination with immunotherapy, no significant improvement in survival outcomes has been observed. The integration of new systemic agents with MDT will likely define a new scenario for the treatment of omUC. The review protocol was registered in PROSPERO, ID: CRD42024522381.

Brachial plexopathy following stereotactic body radiation therapy in apical lung malignancies: A dosimetric pooled analysis of individual patient data.

BACKGROUND AND OBJECTIVES: The aim of this study is to establish dosimetric constraints for the brachial plexus at risk of developing grade ≥ 2 brachial plexopathy in the context of stereotactic body radiation therapy (SBRT). PATIENTS AND METHODS: Individual patient data from 349 patients with 356 apical lung malignancies who underwent SBRT were extracted from 5 articles. The anatomical brachial plexus was delineated following the guidelines provided in the atlases developed by Hall, et al. and Kong, et al.. Patient characteristics, pertinent SBRT dosimetric parameters, and brachial plexopathy grades (according to CTCAE 4.0 or 5.0) were obtained. Normal tissue complication probability (NTCP) models were used to estimate the risk of developing grade ≥ 2 brachial plexopathy through maximum likelihood parameter fitting. RESULTS: The prescription dose/fractionation schedules for SBRT ranged from 27 to 60 Gy in 1 to 8 fractions. During a follow-up period spanning from 6 to 113 months, 22 patients (6.3 %) developed grade ≥2 brachial plexopathy (4.3 % grade 2, 2.0 % grade 3); the median time to symptoms onset after SBRT was 8 months (ranged, 3-54 months). NTCP models estimated a 10 % risk of grade ≥2 brachial plexopathy with an anatomic brachial plexus maximum dose (Dmax) of 20.7 Gy, 34.2 Gy, and 42.7 Gy in one, three, and five fractions, respectively. Similarly, the NTCP model estimates the risks of grade ≥2 brachial plexopathy as 10 % for BED Dmax at 192.3 Gy and EQD2 Dmax at 115.4 Gy with an α/ß ratio of 3, respectively. Symptom persisted after treatment in nearly half of patients diagnosed with grade ≥2 brachial plexopathy (11/22, 50 %). CONCLUSIONS: This study establishes dosimetric constraints ranging from 20.7 to 42.7 Gy across 1-5 fractions, aimed at mitigating the risk of developing grade ≥2 brachial plexopathy following SBRT. These findings provide valuable guidance for future ablative SBRT in apical lung malignancies.

Effects of electron density force to 1.0 and fill to 1.0 on VMAT treatment plans for lung SBRT.

PURPOSE: The aim of this study is to determine the effect of forcing and filling the electron density (ED) to 1.0 of the planning target volume (PTV) overdose distribution in lung SBRT treatment leading to shortening patient treatment time and increasing patient comfort by reducing MU/fraction due to ED manipulation effect. METHODS: In this study, 36 lung SBRT plans of 12 suitable patients who prescribed a total dose of 50 Gy in five fractions were generated with Monaco v.5.10 TPS using the Monte Carlo (MC) algorithm and volumetric modulated arc therapy (VMAT) technique by PTV ED values forcing as well as filling to 1.0 and comparatively assessed. The first group of plans was created by using the patient's original ED, second and third groups of plans were reoptimized by forcing and filling the ED of PTV to 1.0, respectively, therefore acquiring a new dose distribution which lead to comparatively assessment the effects of changes in ED on PTV and OAR doses. RESULTS: Assessment of treatment plans revealed that mean MU/fx numbers were decreased by 76% and 75.25% between Groups 1 and 2, Groups 1 and 3, respectively. The number of segments was also reduced in Group 1 by up to 15% compared with Groups 2 and 3. Maximum HI and CI differences for PTV between Groups 1 and 2 were less than 1% and Groups 1 and 3 were 1.5% which indicates all 3 group plans were comparable in terms of dose distribution within PTV. CONCLUSIONS: Forcing and filling the ED of PTV to 1.0 strategy has provided reduced a number of segments and MU/fx without a significant change in PTV mean and maximum doses, thereby decreasing treatment time and patient discomfort during treatment. This process should be considered in line of a potential number of patients as well as prescribed dose and MU/fx numbers.

Comparison between Trans-Arterial Chemoembolization Followed by Stereotactic Body Radiation Therapy and Trans-Arterial Chemoembolization Alone in BCLC Stage B Hepatocellular Carcinoma: A Pilot Study.

OBJECTIVE: Both Stereotactic Body Radiation Therapy (SBRT) and Trans-arterial Chemoembolization (TACE) are now being widely used to treat advanced hepatocellular carcinoma (HCC) and can improve tumor local control rates. We aimed at evaluating the efficacy and toxicity of combining SBRT and TACE in comparison to TACE alone in unresectable HCC. METHODS: 42 unresectable Barcelona Clinic Liver Cancer (BCLC) stage B HCC Child Pugh (CP) A patients were randomized to receive either: TACE alone (Arm A) or TACE followed by SBRT (Arm B). Dose prescribed was 40Gy in 5consecutive daily fractions over 1 week . We compared the local control (LC), Progression free survival (PFS), overall survival (OS) and toxicity between the two arms. RESULTS: 22 patients were in arm A versus 20 patients in arm B with median follow up 20 months starting recruitment from April 2021 till January 2023. Both LC, PFS were significantly better in Arm B. Complete remission (CR) rate was 54.5% and 75% in Arm A and B, respectively. Median PFS was 16 months in Arm B compared to 11 months in Arm A (p =0.003). Median OS was not reached in both arms. Both arms had comparable toxicities. CONCLUSION: Adding SBRT to TACE in advanced HCC, is safe and feasible with better efficacy in terms of LC and PFS with comparable side effects, in comparison to TACE alone.

DARES: A Phase II Trial of Durvalumab and Ablative Radiation in Extensive-Stage Small Cell Lung Cancer.

BACKGROUND: Immunotherapy in combination with chemotherapy is first-line treatment for patients with extensive-stage small-cell lung cancer (ES-SCLC). Growing evidence suggests that radiation, specifically stereotactic body radiation therapy (SBRT), may enhance the immunogenic response as well as cytoreduce tumor burden. The primary objective of the study is to determine the progression free survival for patients with newly diagnosed ES-SCLC treated with combination multisite SBRT and chemo-immunotherapy (carboplatin, etoposide, and durvalumab). METHODS: This is a multicenter, single arm, phase 2 study. Patients with treatment-naïve, ES-SCLC will be eligible for this study. Patients will receive durvalumab 1500mg IV q3w, carboplatin AUC 5 to 6 mg/mL q3w, and etoposide 80 to 100 mg/m2 on days 1 to 3 q3w for four cycles, followed by durvalumab 1500mg IV q4w until disease progression or unacceptable toxicity. Ablative radiation will be delivered 1 to 4 extracranial sites in 3 or 5 fractions, determined by location, during cycle 2. The primary endpoint is progression-free survival, measured from day 1 of chemoimmunotherapy. Secondary endpoints include grade ≥3 toxicity by CTCAE v5.0 within three months of RT, overall survival, response rate, time to second line systemic therapy, and time to new distant progression. CONCLUSIONS: Now that immunotherapy is an established part of ES-SCLC management, it is important to further optimize its use and effect. This study will investigate the progression-free survival of combined SBRT and chemo-immunotherapy in patients with ES-SCLC. In addition, the data from this study may further inform the immunogenic role of SBRT with chemo-immunotherapy, as well as identify clinical, biological, or radiomic prognostic features.

Prognostic value of circulating tumor cells in oligorecurrent hormone-sensitive prostate cancer patients undergoing stereotactic body radiation therapy.

BACKGROUND: Stereotactic body radiation therapy (SBRT) is an effective metastasis-directed therapy for managing oligometastatic prostate cancer patients. However, it lacks reliable biomarkers for risk stratification. Circulating Tumor Cells (CTC) show promise as minimally invasive prognostic indicators. This study evaluates the prognostic value of CTC in oligorecurrent hormone-sensitive prostate cancer (orHSPC). METHODS: orHSPC patients with 1-3 nodal and/or bone metastases undergoing SBRT were enrolled (N = 35), with a median follow-up time of 42.1 months. CTC levels were measured at baseline (T0), 1 month (T1), and 3 months (T2) post-SBRT using a novel metabolism-based assay. These levels were correlated with clinical outcomes through Cox-regression and Kaplan-Meier analyses. RESULTS: Median CTC counts were 5 at T0, 8 at T1, and 5 at T2 with no significant variation over time. Multivariate analysis identified high (≥5/7.5 mL) T0 CTC counts (HR 2.9, 95% CI 1.3-6.5, p = 0.01, median DPFS 29.7 vs. 14.0 months) and having more than one metastasis (HR 3.9, 95% CI 1.8-8.6, p < 0.005, median DPFS 34.1 vs. 10.7 months) as independent predictors of distant progression-free survival (DPFS). CTC assessment successfully stratified patients with a single metastasis (HR 3.4, 95% CI 1.1-10.2, p = 0.03, median DPFS 42.1 vs. 16.7 months), but not those with more than one metastasis. Additionally, a combined score based on CTC levels and the number of metastases effectively stratified patients. CONCLUSION: The study demonstrates that hypermetabolic CTC could enhance risk stratification in orHSPC patients undergoing SBRT, particularly in patients with limited metastatic burden, potentially identifying patients with indolent disease who are suitable for tailored SBRT interventions.