Outcomes Of Stereotactic Body Radiotherapy Research Articles

Total dose, fraction dose and respiratory motion management impact adrenal SBRT outcome

Purpose/Objective(s)Stereotactic body radiotherapy (SBRT) is an effective treatment for oligometastatic disease in multiple sites. However, the optimal radiation dose for long-term local control of adrenal metastases has yet to be determined. The aim of this study is to evaluate outcomes of adrenal SBRT and to evaluate factors that correlate with local control. Materials/MethodsAfter IRB approval, a retrospective data review of patients treated with SBRT for adrenal metastases at a medical center in Israel between 2015 and 2021 was conducted. A biological effective dose was calculated using an alpha beta ratio of 10. Kaplan Meier and Cox regression were calculated using SPSS software to describe the hazard ratio for local control and survival. Results83 cases of adrenal SBRT were identified. The average age was 67 (range 42–92 years old). Non-small cell lung cancer was the primary site in 44 % of patients. A total of 70 % of the patients had oligometastatic disease (less than five lesions), and the rest were polymetastatic, responding to systemic therapy with oligo progression in the adrenal. The average gross tumor volume (GTV) was 42 ml. Respiratory control was applied in 88 % of cases; 49.3 % used 4-D/ITV, and 38.5 % used breath-hold or continuous positive airway pressure (CPAP) with free breathing. On multivariable analysis, Dose above 75 Gy (biological effective Dose) (HR = 0.41, p = 0.031), Dose above 8 Gy per fraction (HR = 0.53p = 0.038), and breath-holds or CPAP (HR = 0.65, p = 0.047) were significant for local control. From multivariable analysis, we computed a predicted nomogram curve using seven clinical parameters to evaluate local control odds. ConclusionIn this single institution series reported to date, we found unilateral adrenal SBRT safe, yet bilateral treatment harbors a risk of adrenal insufficiency. Biological effective Dose > 75 Gy (BED), motion management with breath-hold or CPAP, and Dose per fraction > 8 Gy were the enhanced local controls. We propose a nomogram to help in decision-making regarding total Dose and Dose per fraction when treating adrenal SBRT.

Abstract PO2-05-11: Patient Perspectives on the Value of Stereotactic Body Radiotherapy (SBRT) in the Management of Breast Cancer: The PERSPECTIVE Study

Abstract Background: Oligometastatic disease describes limited metastases amenable to local therapy such as stereotactic body radiotherapy (SBRT). Within the UK National Health Service (NHS), SBRT is a standard of care for up to 3 metachronous sites of oligometastatic breast cancer (OMBC), offering high local control rates with low toxicity. The SABR-COMET study demonstrated improved progression-free survival (PFS) and overall survival (OS) with SBRT compared to standard of care in a number of oligometastatic cancers, including breast cancer [1]. Conversely, the NRG-002 trial results suggest no PFS or OS improvement with the addition of SBRT to standard systemic therapy in OMBC [2]. The OS data for this study are yet to mature and in the meantime the results of other prospective studies are awaited. As patients’ attitudes and perspectives govern their preferences around treatment decisions, it is vital to understand whether PFS and OS are the most important considerations for patients. This study aims to explore patients’ perspective on the role of SBRT in breast cancer management. Their views will help inform future trial endpoints and support clinicians to support patients with their decision making and expectations. Methods: We conducted an exploratory qualitative study with focus groups and individual interviews, to understand participants knowledge, views and opinions on SBRT in treating breast cancer. All patients were asked to watch an educational video about SBRT in advance of participating in the interviews. An interview guide with open-ended questions was developed. Breast cancer patients were recruited using a purposive sampling matrix based on the patients age, presence of metastatic disease and previous experience with radiotherapy. Each focus group had at least two moderators and all interviews were digitally recorded and then transcribed. The data were managed and coded using NVivo version 12 and analysed using a thematic analysis approach. Results: A total of 18 breast cancer patients participated in this study, with 7 (39%) having primary disease and 11 (61%) with metastatic disease. The study included two focus groups (group one = 5 patients; group two = 9 patients) and four individual interviews conducted between May and June 2023. The participants had a median age of 54 years (range 38-74). The majority of participants (83%) had previous experience with radiotherapy, with 4 (27%) having received SBRT previously for their OMBC. Only 2 (2%) patients who had not previously received SBRT were aware of it before participating in this study. Most of the patients (78%) were Caucasian and 72% had attained at least an undergraduate degree level of education. Throughout the study, three main themes emerged: theme 1 - participants experience with radiotherapy; theme 2 - interests and considerations regarding SBRT (including desired treatment outcomes) and theme 3 - willingness to consider SBRT in absence of a survival benefit. Extending their life was unanimously described as the most important desired outcome of SBRT, followed by quality of life. Other desired treatment outcomes expressed included reduction of tumour size, minimal collateral damage/side effects, relief of symptoms, avoidance of recurrence and increase in time to change of systemic therapy. Conclusion: In our study, while extension of life was a desired treatment outcome of SBRT for OMBC, all participants expressed willingness to consider SBRT for its potential benefits in local control and durable pain control, even in absence of a survival benefit.

Managing hepatocellular carcinoma across the stages: efficacy and outcomes of stereotactic body radiotherapy : Aretrospective study.

Hepatocellular carcinoma (HCC) poses aunique challenge due to its predilection for developing on compromised livers, often limiting surgical options. Stereotactic body radiotherapy (SBRT) has emerged as apromising local treatment modality for HCC. This study aims to assess the effectiveness of SBRT in HCC patients not suitable for surgery, focusing on local control, optimal radiation dosing, and prognostic factors. In this retrospective analysis, 52 HCC patients treated with SBRT were examined. The study assessed local control, progression-free survival (PFS), and overall survival (OS) while conducting dosimetric analyses. The relationship between mean liver dose and Child-Pugh score (CPS) progression was also explored. SBRT demonstrated 93.4% freedom from local progression (FFLP) at 12months. Notably, anear minimum dose (D98%) below 61 Gy as an equivalent dose in 2‑Gy fractions with α/β 10 Gy (EQD2α/β10) was associated with reduced FFLP (p-value 0.034). Logistic regression analysis revealed adose-response relationship for FFLP and D98% with 95% and 98% probability of FFLP at adose of 56.9 and 73.1 Gy, respectively. The study observed OS rates of 63.7% at 1year and 34.3% at 3years. Patients with portal vein tumor thrombus (PVTT) and larger tumors (≥ 37 cm3) experienced decreased PFS and OS. Multivariate analysis identified PVTT, larger tumor volume, and performance status as independent predictors of reduced OS. Notably, classical radiation-induced disease (cRILD) was absent, but nonclassical (nc) RILD occurred in 7.7% of patients. Regression analysis linked amean EQD2α/β3-8 dose to the liver (12.8-12.6) with a10% likelihood of ncRILD. SBRT offers acompelling option for achieving high local control and promising survival outcomes in HCC. The study supports aradiation dose range of 61-73.1 Gy, coupled with amean liver dose under 12.6-12.8 Gy as EQD2, to achieve favorable FFLP rates, with acceptable toxicity rates.

Stereotactic body radiation therapy for clinically diagnosed early‐stage non‐small cell lung cancer: Importance of accurate CT interpretation by experts

AbstractIntroductionThis study evaluated the clinical outcomes of stereotactic body radiotherapy (SBRT) for both pathologically diagnosed (PD) and clinically diagnosed (CD) early‐stage non‐small cell lung cancer (NSCLC) and explored the significance of accurate expert computed tomography (CT) interpretation.MethodsWe retrospectively analyzed 95 patients with early‐stage NSCLC who received SBRT at our institution. Patients were classified into CD and PD groups. Two chest radiologists retrospectively interpreted the pre‐SBRT CT images to determine the tumor subtype and probability of malignancy (PM). Clinical findings, CT features, and treatment outcomes were compared between the two groups. The survival rate of the CD group was analyzed separately according to the PM grade.ResultsMedian overall survival for the CD and PD groups was 6.0 and 5.4 years (P = 0.57), respectively. Median cause‐specific survival was 10.2 years in the CD group and not reached in the PD group (P = 0.76). In the CD group, lung cancer mortality was lower in the low PM group (25% [1 of 4]) than in the high PM group (47.4% [9 of 19]).ConclusionIt may be desirable to evaluate the PM of the nodule using expert CT interpretation to decide whether SBRT is indicated in CD early‐stage NSCLC.

Comparison of outcomes following surgical resection, percutaneous ablation or stereotactic body radiation therapy in early-stage, solitary and small (≤3 cm) treatment-naïve hepatocellular carcinoma.

Stereotactic body radiation therapy (SBRT) is associated with high local control rates in hepatocellular carcinoma (HCC). This study reports the outcomes of SBRT compared to surgical resection (SR) and percutaneous ablation (PA) for treatment-naïve, solitary HCCs ≤3 cm. This was a retrospective study of patients with BCLC stage 0/A HCC with a single ≤3 cm lesion, treated with curative intent between 2016 and 2020. SBRT was used for patients considered unsuitable for SR or PA. The co-primary endpoints were progression-free survival (PFS) and overall survival (OS). The secondary endpoints were treatment-related clinical toxicity rates and local control (LC) rates. There were 112 patients included in this study. SBRT was delivered in 36 patients (32.1%), 51 had PA (45.5%) and 25 underwent SR (22.3%). Median follow-up was 23 months (range, 3-60 months) from diagnosis. The 3-year PFS and OS were 67% and 69% following SBRT, 55% and 80% following PA, and 85% and 100% following SR, respectively. Patients in the SR cohort had significantly better 3-year PFS and OS compared to SBRT and PA groups (p = 0.03 and p = 0.04, respectively). There was no significant difference in PFS (p = 0.15) or OS (p = 0.23) between SBRT and PA treated patients. The 3-year LC rate for the entire cohort was 98%. In patients with treatment-naïve, early-stage solitary HCCs ≤3 cm, SBRT was associated with comparable PFS, OS and LC outcomes to PA. SBRT should be considered as a curative intent therapy to avoid treatment stage migration in this favourable prognostic cohort of patients.

EP07.05-09 Oncologic Outcomes of Stereotactic Body Radiotherapy in Early-Stage Non-Small Cell Lung Cancer Patients with Interstitial Lung Disease

EP07.05-09 Oncologic Outcomes of Stereotactic Body Radiotherapy in Early-Stage Non-Small Cell Lung Cancer Patients with Interstitial Lung Disease

EP07.01-28 Local Control & Toxicity Results of Stereotactic Body Radiotherapy in Central Lung Tumors

EP07.01-28 Local Control & Toxicity Results of Stereotactic Body Radiotherapy in Central Lung Tumors

Multicenter Retrospective Study of Stereotactic Body Radiotherapy for Patients with Previously Untreated Initial Small Hepatocellular Carcinoma.

The effectiveness of stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) has been shown in many studies and its therapeutic effect is similar to radiofrequency ablation (RFA). However, many of these studies were done in combination with transcatheter chemoembolization (TACE), for recurrent HCC, or on a small scale. To better understand the specific outcomes of SBRT for HCC, we conducted a multicenter retrospective analysis of SBRT for previously untreated initial HCC at Japanese Society of Clinical Oncology (JCOG) member hospitals. Patientswho underwent SBRT for HCC at JCOG member hospitals between July 2013 and December 2017 and met the following eligibility criteria were included: (1) initial HCC; (2) ≤ 3 nodules, ≤ 5 cm in diameter; (3) a Child-Pugh (CP) score of A or B; and (4) unsuitability for or refusal of standard treatment, such as surgery, transplantation, RFA and TACE. We evaluated the overall survival (OS), recurrence-free survival (RFS) which was defined as the first instance of intra-hepatic recurrence after SBRT, disease-specific survival (DSS) using Kaplan-Meier analysis. Using Grey's test, patients who died of other diseases were analyzed as competing risks to estimate the cumulative incidence of local recurrence (CLR). Adverse events directly related to SBRT also analyzed using Common Terminology Criteria for Adverse Events version 5.0 (CTCAE v5.0). Seventy-three patients with 79 lesions from 14 hospitals were analyzed. The median age was 77 years (range; 50-89 years), and the median tumor size was 23 mm (range; 6-50 mm). The median radiation dose was 40 Gy (range; 35-60 Gy) in five fractions (range; 4-8). The median follow-up period was 45 months (range; 0-103 months). There were three cases where follow-up was not possible due to unexpected events unrelated to SBRT, while the remaining 70 patients were successfully followed for at least six months. The 2 and 3year OS, RFS, DSS, and CLR rates were 84.3% (95% CI: 75.8-92.8%) and 69.9% (95% CI: 58.7-81%), 67.5% (95% CI: 56.0-79.0%) and 57.9% (95% CI: 45.2-70.5%), 95.1% (95% CI:89.7-100%)/87.6% (95% CI:78.8-96.3%), and 11.4% (95% CI: 5.3-20.0%) and 20.0% (95% CI: 11.2-30.5%), respectively. Four cases (5.5%) of adverse events of grade 3 or higher were reported: one case of grade 3 laboratory toxicities, one case of grade 3 liver failure, one case of grade 3 portal tumor thrombosis, and one case of grade 4 duodenal ulcer. No grade 5 toxicities were observed. The results of our study demonstrate that SBRT for HCC is highly effective in achieving local control and is safe to administer. In addition, survival outcomes are favorable. SBRT is a promising treatment modality, especially for small HCCs for that is not suitable for standard treatment.

Fraction Size, Total Dose and Respiratory Control Impact Local Control in Adrenal SBRT

Stereotactic body radiotherapy (SBRT) is an effective treatment for oligometastatic disease in multiple sites, however, the optimal radiation dose for long term local control of adrenal metastases has not yet been determined. The aim of this study is to evaluate outcomes of adrenal SBRT and to evaluate factors that correlate with local control MATERIALS/METHODS: After IRB approval, a retrospective data review of patients treated with SBRT on adrenal metastases was conducted, at a medical center in Israel between 2015 and 2021. Biologic Equivalent Dose (BED) were calculated using an alpha beta ration of 10. Kaplan Meier and Cox regression were calculated to describe the hazard ratio for local control and survival using statistical software. Fifty-eight cases of adrenal SBRT were identified. The average age was 67 years (ranging 42-92). Forty-three percent of primary tumor was non-small cell lung cancer. The lesions were equally distributed between the right and left adrenal gland. Six patients had bilateral radiation treatment. Fifty-eight percent of the cases were in the setting of oligometastatic disease (less than 5 lesions) with the rest having progression in the adrenal. PET-CT scans were available for follow up in 55% of patients and CT in the rest. The average GTV volume was 42 cm2 respiratory control through 4D and breath hold was performed in 86% of cases. The median follow up time, for local control, was 10 months with a range of 1-54 mos. Univariate analysis local control, during the last follow up, was seen in 74% of cases. Total dosage was equal to or above 72 Gy and dosage per fraction was equal to or above 8 Gy. The use of respiratory motion was found significant for local control. Only a fraction size equal to or above 8 Gy and a total dosage equal to and above 72 Gy were found significant for local failure (HR = 0.26, p = 0.024 and HR = 0.28, p = 0.019). With multivariable analysis the dosage per fraction ≥8 Gy continued to be significant after adjusting for total dose, histology, side, and motion management. Two patients had clinical signs of adrenal insufficiency and both received bilateral adrenal radiation. Bowel toxicity was low: 1 patient had >G3 toxicity. In the largest single institution series reported to date, we found unilateral adrenal SBRT to be safe, however, bilateral treatment harbors a risk of adrenal insufficiency. Dose per fraction ≥8 Gy was the most powerful predictor of local control, and a total dose ≥72gy and motion management were also significant. In conclusion, we propose a treatment regimen with a fraction size of at least 8 Gy and a total dosage of at least 72 Gy for evaluation, in a prospective clinical trial.

Treatment Outcomes and Toxicity Profile of MRI-Guided Gated-Real Time Online Adaptive Stereotactic Body Radiotherapy to Patients with Pancreatic Tumors

Stereotactic body radiation therapy (SBRT) to patients with inoperable pancreas cancer has shown promising outcomes. Dose escalation is challenging given the associated risks to nearby organs at risk and requires treatment plan adaptation and motion management. This study reports the treatment related adverse events and treatment outcomes of MRI-guided SBRT utilizing gated-real time online adaptive radiotherapy to patients with pancreatic tumors. This is a single institution retrospective IRB approved study and included patients with pancreatic tumors who were treated with MRI-guided SBRT utilizing gated-real time online adaptive radiotherapy, consecutively between 2019 and 2022. All patients were treated with 0.35T MRI linear accelerator. All patients' charts and radiation plans were reviewed for this study. The study included 25 patients treated consecutively to 125 radiation fractions with MRI-guided SBRT. The study included 15 females and 10 males, 19 white, 2 Asians, 1 Latin American and 2 African Americans. The median age was 74, and all patients had pancreatic adenocarcinoma (92%) except two patients who had biopsy proven renal cell carcinoma metastatic to the pancreas without evidence of disease elsewhere. Most patients (68%) received chemotherapy (FOLFIRINOX or Gemcitabine / Protein-bound paclitaxel) prior to SBRT. The median dose to gross target volume (GTV) was 50 Gy, and to planning target volume (PTV) was 35 Gy. All patients were treated in 5 radiation fractions. Thirteen patients (52%) received elective nodal irradiation (ENI). All patients had at least a single real-time online adaptive replanning (median 3 fractions, range 1-5 fractions). All treatment fractions were gated (100%) with MRI guidance. The 1-, 2-, & 3- year local-regional control (LRC) were 81%, 57%, & 57% respectively (Median 16 months). The 1-, 2-, & 3- year Distant Control (DC) were 81%, 74%, & 56% respectively (Median 14 months). The 1-, 2-, 3-year overall survival (OS) were 77%, 35%, & 24% (Median 21 months). Planning Target Volume (PTV) dose ≥40Gy was significantly associated with improved local-regional control (p = 0.02). Gross Target Volume (GTV) dose <50Gy was significantly associated with lower DC (p = 0.03). ENI showed a trend towards improved local-regional control but was not statistically significant (p = 0.1). None of the patients experienced ≥ grade 3 toxicities. Most common adverse event were grades 1 or 2 fatigue (24%), nausea (16%), and abdominal discomfort (12%). In this cohort, MRI-guided SBRT utilizing gated-real time online adaptive radiotherapy was a safe and effective approach for patients with pancreatic tumors who are not surgical candidates. In this study, dose escalation was significantly associated with improved local-regional (PTV ≥40 Gy) and distant control (GTV ≥50Gy). None of the patients experienced grade ≥3 radiation induced adverse events.

Functional Outcomes and Toxicities Associated with SBRT to Bone Metastases Involving the Joint Space

Metastatic spread to bone is a common occurrence in advanced malignancies. Stereotactic Body Radiation Therapy (SBRT) is increasingly used for management of bone metastases in both the palliative and oligometastatic settings, especially for radioresistant histologies. Historically, therapeutic radiation to joints has been avoided whenever possible to minimize toxicities such as joint fibrosis and stiffness. Very little data exists to guide the treatment of bone metastases involving or adjacent to the joint space using SBRT. The purpose of this study is to report functional outcomes and toxicities associated with SBRT to metastatic bone lesions involving the joint space. Patients with solid tumor bone metastases involving the joints of long bones who were treated with SBRT (≥500 cGy/fraction; BED10 ≥37.5) who had ≥30 days follow up were identified from our institutional electronic health record using an IRB approved protocol. Pre-treatment and post-treatment pain assessments and toxicities were collected and scored retrospectively. Toxicities were categorized as acute (≤30 days post treatment) or late (>30 days post-treatment). Weidentified 40 evaluable patients with 54 lesions treated with SBRT. Lesions treated included those involving the hip (29/54, 54%), shoulder (11/54, 20%), elbow (8/54, 14%), and knee (6/54, 11%). The most common patient histology treated was renal cell carcinoma (13/40, 33%), followed by prostate adenocarcinoma (7/40, 18%), non-small cell lung cancer (4/40, 10%), and breast cancer (4/40, 10%). The remainder (12/40) had other histologies. Median follow up time was 7.7 months (range = 1.3-55.0). Median prescribed dose was 650 cGy/fraction (range = 500-1300 cGy) and most lesions received 4000 cGy in 5 fractions (18/54, 33%). At >30 days, of the 42 sites where pain was reported pre-treatment, 30/42 (71%) had complete or partial pain relief, while 10/42 (24%) experienced no pain relief during available follow up. Patients reported worsening pain after SBRT in 2/54 (3.7%) of treated lesions. Seven of 54 (14.0%) treated lesions led to complaints of joint stiffness requiring physical therapy. A minority of patients developed insufficiency fractures or treatment failures after SBRT requiring surgery (4/54, 7.4%). Three of 54 patients (5.6%) developed symptomatic radiation myositis confirmed on imaging. Toour knowledge, this is the first study to report functional and toxicity outcomes of SBRT to lesions involving the joints of long bones. While SBRT appears to have acceptable toxicities at the doses reported in this analysis, further study is warranted to identify pre-treatment factors predictive of toxicity. Limitations of the study include its small sample size, retrospective nature, and single institution design. Future studies will focus on dosimetric and clinical factors associated with toxicities which may allow for more personalized treatments and assist with informed consent.

A Pilot Study of Stereotactic Body Radiotherapy and 177Lu-PSMA-617 for Oligometastatic Hormone Sensitive Prostate Cancer

Stereotactic body radiotherapy (SBRT) is increasingly used for oligorecurrent prostate cancer (OPC). Despite excellent local control, distant metastasis free survival rates are more modest. We hypothesized SBRT outcomes could be optimized with improved staging imaging and integration of a well-tolerated targeted radiopharmaceutical therapy (RLT) for microscopic disease. We report initial results of a prospective, single-institution pilot (NCT05079698) of a novel, PSMA-based theranostic strategy for OPC. Men with castrate sensitive OPC and 1-3 sites of PSMA PET avid disease ("index lesions") and no PSMA non-avid sites were eligible. No androgen deprivation therapy was permitted. Subjects first received 2 cycles of 177Lu-PSMA-617 RLT (7.47±0.14 GBq) spaced 6 weeks apart. In vivo dosimetry was performed during cycle 1. Four weeks post-cycle 2, patients were restaged with 68Ga-PSMA PET for an interim (post-RLT) response assessment. Index lesions were then consolidated with SBRT (9 Gy x 3) irrespective of post-RLT PET response. The primary outcome was feasibility defined as successful completion of protocol-mandated therapy without intercurrent distant failure on post-RLT PET. Six men were treated with nine total index lesions (5 nodal, 3 osseous, 1 visceral). The study met its primary endpoint; all completed required interventions and no distant progression was seen on interim PSMA PET. Treatment was well tolerated; no grade 3+ toxicities, 2/6 had grade 2 toxicities (transient anemia and hyperbilirubinemia) and 5/6 had grade 1 toxicities. Median baseline lesion-level PSMA SUVmax was 16.8±8.7. Median interim SUVmax was 6.2±2.5 and declined for all but one lesion post-RLT (median -65%). Median SUVmax at 3-mos post-SBRT was 3.3±2.5 and decreased for all evaluable lesions (median -80%). Median baseline PSA was 2.01 ng/mL (range: 0.72-4.56) which declined in 5/6 post-RLT. The 6th patient experienced biochemical rise with interim PET showing only greater avidity in the known index lesion and SBRT was completed per protocol. All 4 evaluable patients with at least one post-SBRT follow-up have improved PSA at last visit (range 5.5-12 mos from cycle 1), and 2/4 have undetectable PSA. Composite dosimetry, correlatives and quality of life studies are forthcoming. Our pilot study demonstrates the feasibility of a novel PSMA anchored theranostic strategy combining SBRT with targeted RLT for OPC. Preliminary data suggests promising outcomes, including the possibility of achieving an undetectable biochemical disease state without hormone therapy.

Real-World Results of Stereotactic Body Radiotherapy for 399 Medically Operable Patients with Stage I Histology-Proven Non-Small Cell Lung Cancer.

Surgery is the standard treatment for stage I non-small cell lung cancer (NSCLC); however, no clear randomized trial demonstrates its superiority to stereotactic body radiotherapy (SBRT) regarding survival. We aimed to retrospectively evaluate the treatment outcomes of SBRT in operable patients with stage I NSCLC using a large Japanese multi-institutional database to show real-world outcome. Exactly 399 patients (median age 75 years; 262 males and 137 females) with stage I (IA 292, IB 107) histologically proven NSCLC (adenocarcinoma 267, squamous cell carcinoma 96, others 36) treated at 20 institutions were reviewed. SBRT was prescribed at a total dose of 48-70 Gy in 4-10 fractions. The median follow-up period was 38 months. Local progression-free survival rates were 84.2% in all patients and 86.1% in the T1, 78.6% in T2, 89.2% in adenocarcinoma, and 70.5% in squamous cell subgroups. Overall 3-year survival rates were 77.0% in all patients: 90.7% in females, 69.6% in males, and 41.2% in patients with pulmonary interstitial changes. Fatal radiation pneumonitis was observed in two patients, all of whom had pulmonary interstitial changes. This real-world evidence will be useful in shared decision-making for optimal treatment, including SBRT for operable stage I NSCLC, particularly in older patients.

Ten-Year Outcomes of Stereotactic Body Radiotherapy for Oligometastatic Breast Cancer: Does Synchronous Oligometastatic Breast Cancer Benefit?

AimsThe benefit of stereotactic body radiotherapy (SBRT) in metachronous oligometastatic breast cancer (OMBC) has previously been described and its use in current clinical practice is established. The role of SBRT in the management of synchronous OMBC remains uncertain. The aim of this study was to compare outcomes of SBRT-treated synchronous OMBC with those of SBRT-treated metachronous OMBC. Materials and methodsThis was a retrospective analysis of consecutive extracranial OMBC patients treated with SBRT at a single institution between 2011 and 2022. Kaplan–Meier methods were used to calculate progression-free survival (PFS), overall survival, local control and distant control. Log-rank tests were used to test any differences. Cox regression was used for univariate and multivariate analyses to identify predictive factors. Toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE) version 5. ResultsIn total, 74 OMBC patients with 113 lesions were analysed. The median follow-up was 20 months (range 0–98). Seventy per cent of patients presented metachronously and 30% synchronously. 30 Gy in three fractions was most commonly prescribed, resulting in a median biologically effective dose (BED at α/β = 10) of 60 Gy (range 35.7–112.5 Gy). Forty-nine per cent of patients switched systemic therapy post-SBRT (median time to switch: 14 months, range 0–79). Two patients (2%) experienced grade 3 acute toxicities with no grade ≥4 toxicities. At 2 years overall survival was 92.4% and PFS 39.0%, local control 85.9% and distant control 37.0%. For metachronous and synchronous disease, respectively, 2-year local control rates were 86.5% and 85.8% and PFS rates were 35.3% and 48.3%. The median PFS of metachronous and synchronous disease were 18 months and 17 months, respectively (P = 0.86). Predictive factors on multivariate analysis were treated site for overall survival, change in systemic therapy post-SBRT for PFS and BED for local control. ConclusionOur data confirm SBRT as a well-tolerated treatment for OMBC with excellent local control rates regardless of metachronous or synchronous presentation. There is no suggestion that survival outcomes are inferior for synchronous disease. Further prospective studies are required to validate this finding.

Therapeutic Outcome of Stereotactic Body Radiotherapy for Small Hepatocellular Carcinoma Lesions – A Systematic Review and Network Meta-analysis

Surgical resection, stereotactic body radiotherapy (SBRT) and radiofrequency ablation (RFA) have seldom been compared for small hepatocellular carcinoma (HCC). We explored the treatment outcomes of SBRT for small HCC by conducting a network meta-analysis (NMA). We compared the efficacy and safety of surgical resection, RFA and SBRT for liver-confined small HCC (three or fewer lesions with a diameter ≤5 cm). The study endpoint included the odds ratios of the 1-, 3- and 5-year progression/recurrence/disease-free survival (disease progression-free survival; DPFS) and overall survival rates, as well as severe complications. Forty-five studies included 21 468 patients. In the NMA with comparable data, SBRT had comparable 1-, 3- and 5-year DPFS but significantly worse pooled long-term overall survival (3- and 5-year overall survival) than surgical resection (odds ratio 1.39, 95% confidential interval 1.3–1.89; odds ratio 1.33, 95% confidence interval 1.06–1.69, respectively). SBRT was associated with significantly better pooled 1-year DPFS compared with RFA (odds ratio 0.39, 95% confidence interval 0.15–0.97), with the remaining outcomes being comparable. SBRT had significantly less incidence of severe complications compared with surgical resection (odds ratio 0.62, 95% confidence interval 0.42–0.88) and RFA (odds ratio 0.2, 95% confidence interval 0.03–0.94). In conclusion, for small HCCs (≤5 cm) with one to three nodules, SBRT may be favourable to reduce the risks of severe complications. In terms of DPFS, SBRT may be recommended as an alternative first-line therapy for RFA and surgical resection. The results regarding overall survival should be interpreted with caution, considering the potentially uneliminated bias. There is a clear need for well-designed randomised trials to conclusively identify real differences in efficacy between these treatments, especially SBRT and surgical resection.

PO-04-233 MULTIDISCIPLINARY APPROACHES TO TREAT VENTRICULAR ARRHYTHMIAS WITH RADIOABLATION AND CARDIAC SYMPATHECTOMY (MAVERICS)

Ventricular arrhythmias (VAs) are the most lethal arrhythmias. Established therapies to prevent occurrence of VAs include anti-arrhythmic drugs (AADs) and catheter ablation (CA). For patients with recurrent VAs despite AADs and CA, there exist novel treatment modalities such as cardiac sympathetic denervation (CSD) via percutaneous and surgical approach and stereotactic body radiation therapy (SBRT). The current study reports the outcomes of CSD and SBRT from a tertiary care academic center. To report outcomes of CSD and SBRT for treatment of VAs refractory to conventional treatment with AADs and CA. Study comprises all patients undergoing CSD or SBRT at our center from 10/2018 to 10/2021. Patients with less than 2 months of available follow-up data were excluded. Retrospective chart review was performed to collate data for demographics, clinical characteristics, arrhythmia burden before and after novel therapies (maximum 12 months), and complications during study period. Burden of VAs in the form of episodes of anti-tachycardia pacing (ATP) and defibrillator shocks per month were assessed as primary efficacy outcome. Complications during CSD and SBRT were assessed as primary safety outcome. Overall, 25 patients underwent novel therapies for VAs. Thirteen were excluded due to insufficient follow up data. Of 12 included patients, a total of 4, 5, and 3 patients underwent SBRT, CSD, and both CSD/SBRT, respectively. Median age of the study population was 66 years (55-72). The majority of the patients (10/12) were male. Median left ventricular ejection fraction was 30% (25%-34%). Eight patients had non-ischemic cardiomyopathy. Median number of AADs and CA prior to novel therapies was 3 (2-5) and 1 (0-2), respectively. Follow up was available for a median of 12 (12-12) months before and 12 (9-12) months after intervention. Overall, 11 of 12 patients demonstrated a reduction in VA burden. Mean number of ATP and shock episodes was significantly lower after novel therapies (39±43 vs 3±6; p= 0.008). No procedure-related complications were observed during the study period. Incorporation of novel VA treatment modalities is associated with a reduced arrhythmia burden in this single center study. Further studies are warranted to validate these findings.

Efficacy, toxicities, and prognostic factors of stereotactic body radiotherapy for unresectable liver metastases

This study aims to determine the outcomes of stereotactic body radiotherapy (SBRT) for liver metastases in patients not eligible for surgery. This study included 31 consecutive patients with unresectable liver metastases who received SBRT between January 2012 and December 2017; 22 patients had primary colorectal cancer and nine patients had primary non-colorectal cancer. Treatments ranged from 24 Gy to 48 Gy in 3 to 6 fractions over 1 to 2 weeks. Survival, response rates, toxicities, clinical characteristics, and dosimetric parameters were evaluated. Multivariate analysis was performed to identify significant prognostic factors for survival. Among these 31 patients, 65% had received at least one prior regimen of systemic therapy for metastatic disease, whereas 29% had received chemotherapy for disease progression or immediately after SBRT. The median follow-up interval was 18.9 months; actuarial in-field local control rates at 1, 2, and 3 years after SBRT were 94%, 55%, and 42%, respectively. The median survival duration was 32.9 months; 1-year, 2-year, and 3-year actuarial survival rates were 89.6%, 57.1%, and 46.2%, respectively. The median time to progression was 10.9 months. Stereotactic body radiotherapy was well-tolerated, with grade 1 toxicities of fatigue (19%) and nausea (10%). Patients who received post-SBRT chemotherapy had significant longer overall survival (P=0.039 for all patients and P=0.001 for patients with primary colorectal cancer). Stereotactic body radiotherapy can be safely administered to patients with unresectable liver metastases, and it may delay the need for chemotherapy. This treatment should be considered for selected patients with unresectable liver metastases.

Clinical Outcome of Stereotactic Body Radiotherapy in Patients with Early-Stage Lung Cancer with Ground-Glass Opacity Predominant Lesions: A Single Institution Experience.

The detection rate of early-stage lung cancer with ground-glass opacity (GGO) has increased, and stereotactic body radiotherapy (SBRT) has been suggested as an alternative to surgery in inoperable patients. However, reports on treatment results are limited. Therefore, we performed a retrospective study to investigate the clinical outcome after SBRT in patients with early-stage lung cancer with GGO-predominant tumor lesions at a single institution. This study included 89 patients with 99 lesions who were treated with SBRT for lung cancer with GGO-predominant lesions that had a consolidation-to-tumor ratio of ≤0.5 at Asan Medical Center between July 2016 and July 2021. A median total dose of 56.0 Gy (range, 48.0-60.0) was delivered using 10.0-15.0 Gy per fraction. The overall follow-up period for the study was median 33.0 months (range, 9.9 to 65.9 months). There was 100% local control with no recurrences in any of the 99 treated lesions. Three patients had regional recurrences outside of the radiation field, and three had distant metastasis. The 1-year, 3-year, and 5-year overall survival rates were 100.0%, 91.6%, and 82.8%, respectively. Univariate analysis revealed that advanced age and a low level of diffusing capacity of the lungs for carbon monoxide were significantly associated with overall survival. There were no patients with grade ≥3 toxicity. SBRT is a safe and effective treatment for patients with GGO-predominant lung cancer lesions and is likely to be considered as an alternative to surgery.

Stereotactic Body Radiation Therapy for Sarcoma Pulmonary Metastases.

Lung metastases are the most common form of distant failure for patients diagnosed with sarcoma with metastasectomy considered for some patients with limited metastatic disease and good performance status. Alternatives to surgery such as stereotactic body radiation therapy (SBRT) can be considered, though data are limited. We present outcomes after SBRT for sarcoma lung metastases. Fifty sarcoma patients with 109 lung metastases were treated with SBRT between 2005 and 2021. Outcomes evaluated included local control (LC), overall survival (OS), and toxicity including lung pneumonitis/fibrosis, chest wall toxicity, dermatitis, brachial plexus, and esophageal toxicity. Systemic therapy receipt before and after SBRT was recorded. SBRT schedules were divided into 3 cohorts: 30 to 34Gy/1fx (n=10 [20%]), 48 to 50Gy/4 to 5fx (n=24[48%]), and 60Gy/5fx (n=16[32%]). With a median follow-up of 19.5 months, 1/3-year LC rates were 96%/88% and 1/3-year OS 77%/50%, respectively. There was no differences between the 3 regimens in terms of LC, OS, or toxicity. Size >4cm was a predictor of worse LC ( P =0.031) and worse OS ( P = 0.039) on univariate analysis. The primary pattern of failure was new metastases (64%) of which the majority were in the contralateral lung (52%). One-year chemotherapy-free survival was 85%. Overall, 76% of patients did not require chemotherapy initiation or change of chemotherapy regimen after lung SBRT. Toxicity was reported in 16% of patients overall, including 25%, 20%, and 14% in the 30 to 34Gy/1fx, 48 to 50Gy/4 to 5fx, and 60Gy/5fx cohorts, respectively. SBRT outcomes for lung metastases from sarcoma demonstrate high rates of LC and are similar with different dose/fractionation regimens. Lung SBRT is associated with prolonged chemotherapy-free survival. Prospective validation of these results is warranted.

Comparison of long-term outcomes of stereotactic body radiotherapy (SBRT) via Helical tomotherapy for early-stage lung cancer with or without pathological proof

BackgroundStereotactic body radio therapy (SBRT) has emerged as a standard treatment option for nonsurgical candidates with early-stage non-small cell lung cancer (NSCLC). Pathological proof is sometimes difficult to obtain in patients with solitary pulmonary nodules (SPNs). We aimed to compare the clinical outcomes of stereotactic body radiotherapy via helical tomotherapy (HT-SBRT) for early-stage lung cancer patients with or without a pathological diagnosis.MethodsBetween June 2011 and December 2016, we treated 119 lung cancer patients with HT-SBRT, including 55 with a clinical diagnosis and 64 with a pathological diagnosis. Survival outcomes, including local control (LC), progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS), were compared between two cohorts with and without a pathological diagnosis.ResultsThe median follow-up for the whole group was 69 months. Patients with a clinical diagnosis were significantly older (p = 0.002). No significant differences were observed between the clinical and pathological diagnosis cohorts in terms of the long-term outcome, with 5-year LC, PFS, CSS, and OS of 87% versus 83% (p = 0.58), 48% versus 45% (p = 0.82), 87% versus 84% (p = 0.65), and 60% versus 63% (p = 0.79), respectively. Recurrence patterns and toxicity were also similar.ConclusionsEmpiric SBRT appears to be a safe and effective treatment option in a multidisciplinary setting when patients with SPNs highly suggestive of malignancy are unable/refuse to obtain a definitive pathological diagnosis.