Role Of Stereotactic Body Radiation Therapy Research Articles

Current usage of stereotactic body radiotherapy for oligometastatic prostate cancer in Korea: patterns of care survey (KROG 19-08).

BackgroundGrowing evidence suggests that metastasis-directed therapy and/or prostate-directed therapy may benefit patients with oligometastatic prostate cancer (OMPC). Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastases in various cancers. The purpose of this study was to investigate the current patterns of curative-intent SBRT for OMPC in Korea.MethodsA 20-item questionnaire was sent to 326 radiation oncologists in 93 institutions in Korea. Only 1 physician per institution was required to complete the survey. Subsequently, the second survey consisting of 3 clinical scenarios was sent to 64 physicians with clinical experience in SBRT: case 1, cT4N0M1 (direct invasion to two pelvic bones); case 2, cT2N0M1 (three bone metastases); and case 3, solitary spine metastasis after radical prostatectomy.ResultsSeventy-six physicians from 93 institutions (82%) answered the first survey. The multidisciplinary team approach was practiced in 16 institutions (21%). Most physicians (75%) agreed on the definition of oligometastases as limited lesions and/or organs ≤5: 25% agreed with low-volume disease according to CHAARTED trial. During the last year, 49 physicians (64%) treated OMPC patients with curative intent. Sixty four physicians (84%) had a clinical experience with SBRT: 48 (75%) stated that both dose and fraction number should be considered when defining SBRT, whereas others (25%) stated that only fraction size should be considered. Fifty-five faculties (86%) answered the second survey. Physicians agreed with oligometastases in 89% for case 1, in 80% for case 2, and in 100% for case 3. The rate of SBRT application was the highest in case 3 (70%).ConclusionsThere was diversity in the patterns of SBRT for OMPC in Korea. Additional prospective studies are necessary to strengthen evidence regarding role of SBRT in OMPC.

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

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

Stereotactic radiotherapy in intrahepatic cholangiocarcinoma: A systematic review.

Among biliary tract cancers, intrahepatic cholangiocarcinoma (ICC) has different characteristics compared with those in other sites. Current guidelines suggest several treatment options for ICC, including stereotactic body radiation therapy (SBRT). However, the role of SBRT in locally advanced ICC is unclear. The aim of the present study was to present a systematic review on the efficacy and safety of SBRT in ICC. A systematic review based on the PRISMA methodology was performed. Only papers reporting outcomes in terms of overall survival (OS) after SBRT in inoperable patients with ICC were included. Secondary aims were local control (LC), progression-free survival (PFS) and treatment-related toxicity. Six papers (145 patients) were included in the present analysis. SBRT was frequently used as a salvage treatment, since 28.6-66.7% of patients received previous systemic or local treatments. The median SBRT dose was 45 Gy delivered in 3-5 fractions. The median follow-up was 16 months, and median OS time was 14 months (range, 10-48 months). In one of the included studies, SBRT was significantly superior in terms of OS compared with both chemoradiation and trans-arterial-radio-embolization. The 1-year LC rate was 85% in one study, and 1-year PFS rates were 50 and 68% in two studies, respectively. Toxicity was generally not reported in detail or was reported including other sites of biliary cancers. Overall, limited evidence was available on the efficacy of SBRT in ICC, which should be further investigated in prospective studies with a larger number of patients. However, based on the available data, SBRT seems to produce similar results compared with other ICC treatments, with the advantage of being a very short and non-invasive therapy. Therefore, SBRT should be considered in selected patients with ICC.

OLIGO-AIRO: a national survey on the role of radiation oncologist in the management of OLIGO-metastatic patients on the behalf of AIRO.

In the last years, several evidences demonstrated the role of stereotactic body radiotherapy (SBRT) in the oligometastatic disease and the possibility to increase survival in selected patients. In 2020 the study group "biology and treatment of the oligometastatic disease" of the Italian Association of Radiotherapy and Clinical Oncology (AIRO) conducted a survey evaluating the attitude of physicians in treating the oligometastatic disease and the definition of it. An electronic questionnaire was administered online to the society members. 105 questionnaires were returned. 78% responders considered as oligometastatic a disease with ≤ 5 metastases. The majority of the responders (77%) treated > 50 patients in the last year, and 89% responders agreed in considering every oligometastatic tumor susceptible to local treatments. Regarding the clinical management of the oligometastatic disease, the majority of the responders (66%) suggested an interdisciplinary discussion. When choosing a treatment option for fit patients with a single oligometastatic focus, 52% of the responders agreed in proposing only SBRT. In the case of unfit patients with a single oligometastatic lesion the agreement was in favor of the SBRT alone (89%). In the oligoprogressive setting, 41% responders opted to continue the current systemic treatment and to add SBRT, while in the case of oligoresidual disease, 70% responders was in favor of adding SBRT and continuing the current systemic treatment. In conclusions, the survey illustrated the current agreement and prescribing attitude for oligometastatic patients in Italy. The non-homogenous agreement in some clinical scenarios suggest the need of more robust evidence.

Prevalence of oligoprogression in metastatic hormone-resistant prostate cancer patients on androgen targeted therapies: Could targeted radiotherapy improve patient outcomes?

110 Background: Androgen receptor-targeted therapies (ART) such as Abiraterone and Enzalutamide have shifted the management paradigm of metastatic castrate-resistant prostate cancer (mCRPC). These treatments are well-tolerated with less toxicities compared to chemotherapy, therefore methods to delay chemotherapy are beneficial to patients. Patients eventually become resistant to ARTs, and some patients will progress in a limited number of sites. This study investigated the prevalence of oligoprogressive disease (OPD) amenable to Stereotactic-body radiotherapy (SBRT). OPD is defined as ≤3 metastatic lesions which are progressing or new whilst all other sites of disease are well-controlled by ART. Methods: Retrospective analysis of electronic patient records and imaging studies of 95 patients treated with ART for mCRPC between April 2015 – 2017 from a single centre was undertaken. Data was analysed at the time of first tumour progression on ART. Results: The median (IQR) age of patients was 78.8 (74.4-83.6) years. OPD was found in 27 (28%) patients, 18 (19%) had lesions suitable for SBRT (Table). Seventeen (63%) patients were treated with abiraterone, 10 (27%) patients with enzalutamide. Median (IQR) time from starting ART to OPD was 16.4 (8.6-19.9) months. Five (19%) patients had 3 sites of OPD, 8 (29%) patients had 2 sites of OPD and 14 (52%) patients had 1 site of OPD. Nineteen patients continued ART beyond OPD for ≥3months. OPD was diagnosed using CT scan (56%), whole body diffusion-weighted MRI (22%), choline PET/CT (19%) and bone scan (3%). Six (22%) patients were treated with radiotherapy for OPD, 3 as participants of the TRAP trial (NCT03644303). Median time to subsequent progression after OPD for the 3 patients treated off trial with radiotherapy was 20.5 months. The OPD lesions treated with radiotherapy included the prostate (2 patients, 30 Gy in 5 and 24 Gy in 4 fractions) and para-aortic lymph node (1 patient, 30 Gy in 5 fractions). Median time to subsequent progression after OPD for those who did not receive radiotherapy was 6.4 months. There was no significant difference between median overall survival between patients with OPD and those who progressed with > 3 lesions (7 vs 9.2 years, P= 0.54). Ten (66%) patients who progressed after initial OPD on continuation of ART progressed with further OPD (≤3 lesions including original OPD lesion). Conclusions: OPD is prevalent in patients on ART for mCRPC. The most frequent site of OPD was in bone and majority of patients had only 1 site of OPD at presentation. These results identify a cohort of patients who may benefit from SBRT to maximise ART treatment. Fourteen (14%) patients met entry criteria for TRAP trial which is currently testing the role of SBRT to sites of OPD in mCRPC. [Table: see text]

Stereotactic Body Radiotherapy for High-Risk Prostate Cancer: A Systematic Review.

Simple SummaryStereotactic body radiotherapy, i.e., high-precision radiotherapy delivering high doses within a few treatment sessions, is a very convenient treatment option, which has been shown to be effective and well tolerated in prostate cancer patients with low- or intermediate-risk profiles. This review summarizes the available data and analyzes, whether this modern treatment may routinely be offered to prostate cancer patients with a high-risk profile.Background: Radiotherapy (RT) is an established, potentially curative treatment option for all risk constellations of localized prostate cancer (PCA). Androgen deprivation therapy (ADT) and dose-escalated RT can further improve outcome in high-risk (HR) PCA. In recent years, shorter RT schedules based on hypofractionated RT have shown equal outcome. Stereotactic body radiotherapy (SBRT) is a highly conformal RT technique enabling ultra-hypofractionation which has been shown to be safe and efficient in patients with low- and intermediate-risk PCA. There is a paucity of data on the role of SBRT in HR PCA. In particular, the need for pelvic elective nodal irradiation (ENI) needs to be addressed. Therefore, we conducted a systematic review to analyze the available data on observed toxicities, ADT prescription practice, and oncological outcome to shed more light on the value of SBRT in HR PCA. Methods: We searched the PubMed and Embase electronic databases for the terms “prostate cancer” AND “stereotactic” AND “radiotherapy” in June 2020. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Results: After a rigorous selection process, we identified 18 individual studies meeting all selection criteria for further analyses. Five additional studies were included because their content was judged as relevant. Three trials have reported on prostate SBRT including pelvic nodes; 2 with ENI and 1 with positive pelvic nodes only. The remaining studies investigated SBRT of the prostate only. Grade 2+ acute genitourinary (GU) toxicity was between 12% and 46.7% in the studies investigating pelvic nodes irradiation and ranged from 0% to 89% in the prostate only studies. Grade 2+ chronic GU toxicity was between 7% and 60% vs. 2% and 56.7%. Acute gastrointestinal (GI) grade 2+ toxicity was between 0% to 4% and 0% to 18% for studies with and without pelvic nodes irradiation, respectively. Chronic GI grade 2+ toxicity rates were between 4% and 50.1% vs. 0% and 40%. SBRT of prostate and positive pelvic nodes only showed similar toxicity rates as SBRT for the prostate only. Among the trials that reported on ADT use, the majority of HR PCA patients underwent ADT for at least 2 months; mostly neoadjuvant and concurrent. Biochemical control rates ranged from 82% to 100% after 2 years and 56% to 100% after 3 years. Only a few studies reported longer follow-up data. Conclusion: At this point, SBRT with or without pelvic ENI cannot be considered the standard of care in HR PCA, due to missing level 1 evidence. Treatment may be offered to selected patients at specialized centers with access to high-precision RT. While concomitant ADT is the current standard of care, the necessary duration of ADT in combination with SBRT remains unclear. Ideally, all eligible patients should be enrolled in clinical trials.

Radiation Therapy for Small-Cell Lung Cancer: ASCO Guideline Endorsement of an ASTRO Guideline.

The American Society for Radiation Oncology (ASTRO) produced an evidence-based guideline on radiation therapy (RT) for small-cell lung cancer (SCLC). Because of the relevance of this topic to ASCO membership, ASCO reviewed the guideline, applying a set of procedures and policies used to critically examine guidelines developed by other organizations. The ASTRO guideline on RT for SCLC was reviewed for developmental rigor by methodologists. Then, an ASCO Expert Panel reviewed the content and the recommendations. The ASCO Expert Panel determined that the recommendations from ASTRO guideline on RT for SCLC, published in June 2020, are clear, thorough, and based upon the most relevant scientific evidence. ASCO endorsed ASTRO guideline on RT for SCLC with a few discussion points. Recommendations addressed thoracic radiotherapy for limited-stage SCLC, role of stereotactic body radiotherapy in stage I or II node-negative SCLC, prophylactic cranial radiotherapy, and thoracic consolidation for extensive-stage SCLC.Additional information is available at www.asco.org/thoracic-cancer-guidelines.

The current role of surgery and SBRT in early stage of small cell lung cancer

Early stage small cell lung cancer (T1-2N0M0SCLC) represents 7% of all SCLC. The standard treatment in patients with intrathoracic SCLC disease is the use of concurrent chemoradiotherapy (CRT). Nowadays, the recommended management of this highly selected group is surgical resection due to favorable survival outcomes. For medically inoperable patients or those who refuse surgery, there is an increasing interest in evaluating the role of Stereotactic Body Radiotherapy (SBRT) for T1-2N0SCLC, transferring the favorable experience obtained on inoperable NSCLC (Non-Small-cell Lung Cancer). In the era of multimodality treatment, adjuvant systemic therapy plays an important role even in the management of early SCLC, increasing the disease-free survival (DFS) and Overall Survival (OS). The benefit of Prophylactic Cranial Irradiation (PCI), that currently has a Category I recommendation for localized stage SLCL, remains controversial in this selected subgroup of patients due to the lower risk of brain metastasis. This review summarizes the most relevant data on the local management of T1-2N0M0SCLC (surgery and radiotherapy), and evaluates the relevance of adjuvant treatment. Provides a critical evaluation of best current clinical management options for T1-2N0M0 SCLC.

Stereotactic body radiation therapy (SBRT) in recurrent, persistent or oligometastatic gynecological cancers

ObjectiveSBRT is a well-tolerated technique and provides local-regional control in a variety of metastatic and recurrent tumor types. The role of SBRT in extracranial recurrent, persistent, or oligometastatic gynecological tumors is not well-studied. We therefore retrospectively analyzed a sizeable number of patients in this setting. MethodsWe performed a retrospective review of 86 patients with 209 tumors treated at our institution with SBRT for recurrent, persistent, or oligometastatic extracranial gynecological tumors. The median follow-up was 20 months (range 1–91). The median SBRT dose was 24 Gy (range 10–50) delivered in a median of 4 fractions (range 1–6). The Kaplan-Meier curves and log rank tests were used to assess local control (LC) and overall survival (OS). Cox proportional hazards model was used to evaluate for covariates associated with LC and OS. ResultsThe 1- and 3-year LC were 80% and 68% respectively. The 1- and 3-year OS were 70% and 39%. 32% of the lesions demonstrated complete response, 23% partial response and 20% stable disease. SBRT achieved better local control in smaller tumors. Toxicity was typically mild with grade 1 gastrointestinal toxicity and fatigue being the most common. Only 4.3% of treatments resulted in grade 2 or greater toxicity. There was only one case of grade 3 and no grade 4 or 5 toxicities. ConclusionsSBRT offers a high rate of local control with low incidence of toxicity, mainly grade 1 GI toxicity and fatigue, and provides effective salvage therapy for oligometastatic extracranial pelvic and extra-pelvic gynecological tumors.

Radiation Therapy in the Management of Oligometastatic Breast Cancer: Current Evidence and Future Directions

To review the role of radiation therapy and specifically metastasis-directed stereotactic body radiation therapy (SBRT) in the management of patients with oligometastatic breast cancer with emphasis on potential toxicities and future directions. Recent prospective studies have demonstrated encouraging initial results indicating the potential efficacy of metastasis-directed SBRT in the management of patients with oligometastatic disease. However, given potentially significant toxicities associated with metastasis-directed SBRT, additional data in the form of phase III randomized control trials are needed to define the role of SBRT in the management of patients with oligometastatic breast cancer; such studies are currently ongoing. While current data are encouraging, additional data are required to determine the benefit of SBRT in patients with oligometastatic breast cancer. Physicians opting to treat patients with metastasis-directed SBRT should ideally do so on protocol.

Stereotactic body radiotherapy (SBRT) in metachronous oligometastatic prostate cancer: a systematic review and meta-analysis on the current prospective evidence

In contrast to traditional views of incurability, patients with oligometastatic disease present with an opportunity for disease eradication with aggressive treatment. There is mounting evidence in support of the role of stereotactic body radiotherapy (SBRT) in oligometastatic prostate cancer (OMPC). MEDLINE and EMBASE were queried for prospective cohort studies reporting the outcomes of metachronous OMPC treated with SBRT. The primary outcome was overall local control. Secondary outcomes included androgen deprivation therapy-free survival (ADTFS), biochemical recurrence free survival (BCFS), and progression-free survival (PFS). When appropriate, these endpoints were combined in a meta-analysis. We screened 356 abstracts and identified 10 studies to include in our analysis, with a total of 653 patients and 1,111 lesions. The maximum number of lesions included in any single study ranged from 3 to 5. PET-CT staging occurred in 92.4% of all patients. SBRT dose varied, with BED1.5 ranging from 152 to 408. Only one Grade 3 bone toxicity was observed. Meta-analysis reported an overall local control rate of 97% (95% CI, 94-100). Median ADTFS was 24.7 months (95% CI, 20.1-29.2 months). Two-year BCFS, PFS, and ADTFS were 33% (95% CI, 11-55), 39% (95% CI, 24-54), and 52% (95%CI, 41-62), respectively. Patients treated with SBRT were half as likely to experience PSA progression than those on observation when looking at randomized control trial data alone. SBRT appears to be effective in controlling overall disease burden in metachronous OMPC patients and is associated with minimal significant toxicity. The current prospective literature is scarce, and further prospective data are needed to guide treatment recommendations. This study provides a comprehensive summary of the prospective evidence reporting the outcomes of SBRT in the management of OMPC patients. We quantify the rates of local control, biochemical-free recurrence, progression-free survival, and ADT-free survival through meta-analysis.

Stereotactic Body Radiation for Refractory Ventricular Tachycardia in Patients with Left Ventricular Assist Devices

Stereotactic body radiation therapy (SBRT) combined with electrocardiographic mapping has emerged as a potential noninvasive ablation technique for the treatment of refractory ventricular tachycardia (VT). The role of SBRT in patients with a left ventricular assist device (LVAD) is unknown. Retrospective chart review was performed on all heart failure (HF) patients who underwent SBRT from January 1, 2018 to September 1, 2019. In this case series, we describe two patients who underwent SBRT after LVAD implantation. Of eleven heart failure patients who underwent SBRT, two had LVADs. The first was a 51 year old male with nonischemic cardiomyopathy and ventricular tachycardia refractory to medical therapy and stellate ganglion block. Given his intractable VT and cardiogenic shock, he underwent HeartMate 3 LVAD implantation as bridge-to-transplant (BTT). After LVAD implantation, he continued to have refractory VT despite subsequent VT ablations. CT cardiac mapping identified a 4 mm arrhythmic scar along the lateral wall of the right ventricle, and SBRT was performed with a single fraction of 25 Gy. Two weeks after SBRT, he experienced recurrent VT and eventually underwent orthotopic heart transplantation (OHT) four months after VT recurrence. The second patient was a 66 year old male with a history of nonischemic cardiomyopathy status post HeartWare LVAD as BTT who presented with recurrent VT three years following LVAD implantation. He was referred for SBRT after failure of antiarrhythmic drug (AAD) therapy and VT ablation. 4D-CT simulation defined a myocardial scar in the left ventricular outflow tract, and SBRT was performed with a single fraction of 25 Gy. His ventricular arrhythmias returned after four months, and additional AAD were utilized to suppress the arrhythmias until he underwent OHT two months later. The frequency of hospitalizations for VT did decrease following SBRT (Pt 1: 6 pre-SBRT vs. 3 post-SBRT, Pt 2: 4 pre-SBRT vs. 2 post-SBRT), but did not reach statistical significance (p= 0.12). LVAD patients are prone to ventricular arrhythmias, and noninvasive SBRT may serve as an alternative therapy if AAD and traditional VT ablation have been unsuccessful, potentially keeping ventricular arrhythmias quiescent while awaiting heart transplantation. Further research is needed in this patient population.

Survival of Primary Stereotactic Body Radiation Therapy Compared With Surgery for Operable Stage I/II Non-small Cell Lung Cancer

Stereotactic body radiation therapy (SBRT) is an accepted primary treatment option for inoperable early-stage non-small cell lung cancer (NSCLC). The role of SBRT in the treatment of operable disease remains unclear. We retrospectively evaluated patients with operable early-stage NSCLC who elected to receive primary SBRT, examined factors associated with SBRT, and compared overall survival after surgical resection and SBRT. The National Cancer Database was queried for patients with stage I/II, N0 NSCLC from 2004 to 2016. The proportion of patients who refused recommended surgery and were treated with SBRT was calculated. A propensity score predicting the probability of refusing surgery and receiving SBRT was generated and used to match SBRT and resected patients. Long-term overall survival was compared in the matched cohort using the Kaplan-Meier method and Cox regression. We identified 1359 patients (0.98%) who refused recommended surgery and elected SBRT. This proportion increased annually, from 0.1% in 2004 to 1.7% in 2016. Factors associated with SBRT were older age, black race, Medicaid coverage, lower T stage, and more recent diagnosis year. Propensity matching resulted in 1315 well-balanced pairs. Surgery was associated with higher median survival (74 vs 47 months, P < .01) in the matched cohort. Survival benefit persisted after adjusting for covariates on Cox regression (hazard ratio, 1.69; P < .01). Median survival was significantly higher after surgery compared with SBRT in a risk-adjusted matched cohort of patients judged to be surgical candidates. Operable patients considering primary SBRT should be educated regarding this difference in survival.

Optimized stereotactic volumetric modulated arc therapy as an alternative to brachytherapy for vaginal cuff boost. A dosimetric study

We evaluate the role of stereotactic body radiotherapy using volumetric modulated arc therapy (VMAT) technique as an alternative to high-dose rate brachytherapy (HDR-BT) in the treatment of vaginal cuff in postoperative endometrial cancer. CT scans of 8 patients were used in this study. The clinical target volume (CTV) was defined as the 0.5 cm tissue around the applicator (then subtracting the applicator). Total dose was 30Gy delivered in 5 fractions. In HDR-BT, dose was prescribed at a distance of 0.5 cm from the surface applicator. For VMAT irradiation, a planning target volume (PTV) was obtained from CTV by an expansion of 3 mm. Two VMAT plans were generated using a full arc rotation. The first plan was optimized with an anatomy-based optimization module (PO-VMAT) using a 1mm multileaf collimator beam margin to enhance dose heterogeneity and dose fallout outside the target. The second plan was generated with a full-inverse planning module (FI-VMAT). Conformity (CI100, CI50, CI25), gradient (GI) indexes, and integral doses were calculated. To account for various dose heterogeneity distributions we calculated the equivalent uniform dose (EUD) using the Niemerko model. A Kruskal-Wallis analysis of variance followed by Dunn’s-type multiple comparisons was performed. Dose distributions were more heterogeneous with HDR-BT: Dmean was 144.2% of prescription dose for CTV in HDR-BT and 118.5 and 108.6% for PTV in PO-VMAT and FI-VMAT, respectively. The mean values of EUD for CTV were 136.9%, 130.0 %, and 111.0% of prescription dose in HDR-BT, PO-VMAT, and FI-VMAT plans, respectively. GI indexes were 2.81, 3.41, and 4.14 for HDR-BT, PO-VMAT, and FI-VMAT, respectively. Near-maximal doses (D0.1cc) for rectum and bladder were significantly higher in HDR-BT plans compared to PO-VMAT and FI-VMAT plans (rectum: 131.2% vs112.8% vs 112.0%, respectively; bladder: 129.2% vs 108.7%, and 109.8%, respectively). PO-VMAT plans were able to mimic the HDR-BT dose distribution, showing a successful capability of highly conformal dose distribution, EUD values similar to HDR-BT, and steep dose-gradient outside PTV, then providing a reasonable alternative to brachytherapy.

The Role of Stereotactic Body Radiotherapy (SBRT) in Locally Advanced Hepatocellular Carcinoma Versus Transarterial Chemoembolization (TACE): A Prospective, Non-Randomized Observational Trial (HERACLES)

The Role of Stereotactic Body Radiotherapy (SBRT) in Locally Advanced Hepatocellular Carcinoma Versus Transarterial Chemoembolization (TACE): A Prospective, Non-Randomized Observational Trial (HERACLES)

Which patients benefit most from stereotactic body radiotherapy or surgery in medically operable non-small cell lung cancer? An in-depth look at patient characteristics on both sides of the debate.

The role of stereotactic body radiotherapy (SBRT) in early stage medically operable non‐small cell lung cancer is currently under debate. SBRT's advantage is its ability to provide high radiotherapy doses to a tumor in a short timeframe, without the risk of postoperative complications and mortality. Currently, in part due to limited prospective data comparing both treatments, international guidelines continue to recommend surgical resection as the gold standard for medically operable patients. However, not all patients possess uniform characteristics, and there is some evidence that certain subgroups of patients would benefit more from one form of treatment ‐ SBRT or surgery ‐ than the other. The aim of this review is to provide a brief summary of the evidence comparing SBRT to surgery, followed by a deeper discussion of the subgroups of patients who would benefit most from surgery: those with large tumors, centrally located tumors, increased risk of occult nodal metastases, increased risk of toxicity from radiotherapy and radioresistant histological tumor subtypes. Meanwhile, patients who could benefit most from SBRT might include elderly patients, those with reduced lung function or cardiac comorbidities, those with synchronous lung nodules, and those with specific tumor mutational status. We hope that this review will aid in the clinical decision‐making process regarding patient selection for either treatment.

Implementing and Improving Pancreas SBRT: One Challenge at a Time

The role of stereotactic body radiotherapy (SBRT) is being investigated as an alternative to long-course chemoradiation in select patients with locally advanced pancreatic cancer. Implementation of this technique is complex and fraught with challenges including the proximity of dose sensitive organs, target visibility for image guidance and respiratory motion. Pancreas SBRT was introduced at our institution in 2015 and the technique has undergone multiple iterations since with the goal of improving outcomes. The aim of our current work is to establish optimal respiratory motion management for pancreas SBRT. Initially, all pancreas SBRT cases were treated with a 3 fraction regimen (21-36 Gy) using abdominal compression to minimize respiratory motion. Patients were required to have a biliary stent in situ or fiducial markers implanted prior to simulation for image guidance. Based on our initial local control and toxicity results, institutional policy changed to a 5 fraction regimen (30-50 Gy). Abdominal compression is beneficial for minimizing motion and immobilizing the patient; however, there is a concern that it also causes anatomic deformation to organs at risk (OARs) such as the stomach and duodenum, moving them closer to the target. Thus, an upfront motion assessment was introduced to determine if motion management was necessary. At the time of planning, a free breathing low dose 4D computed tomography (4DCT) scan is acquired to quantify the pancreatic motion using the fiducials. If motion amplitude is <5mm, planning proceeds without abdominal compression, potentially eliminating the problem of moving the OARs into the high dose region. If on free breathing, the motion amplitude is >5mm, either abdominal compression or Active Breathing Coordinator (ABC) is required. For patients where ABC treatment is an option, breath hold and stability assessments will follow to confirm they are suitable candidates. Performing motion assessment prior to CT simulation allows for a more personalized approach to treating patients with pancreas SBRT. Treating patients without the abdominal plate provides greater comfort for patients and has potential dosimetric benefits for OARs. As access to MRI for simulation/planning increases, the free breathing option can readily be built upon as it does not rely on any treatment accessories. Unfortunately, motion evaluation is currently limited to patients with fiducials because stents are not reliable surrogates for motion as they are quite mobile themselves. Interpreting a complex decision tree like this can be confusing for those performing the simulation, making communication and education integral to the success of the program. To date, 18 patients have undergone motion assessment. Five patients were treated free-breathing, 12 patients with abdominal compression, and 1 with ABC. The 12 patients simulated with abdominal compression had an average motion reduction of 9.2 mm to 5.2 mm, confirming the effectiveness of abdominal compression. To quantify intrafraction motion for the free-breathing option, post treatment Cone Beam Computed Tomography (CBCT) images were acquired after every fraction. Upon analysis of the CBCT data, an average overall shift of only 1.5 mm was seen, suggesting there are no issues with stability. The development of 3 different methods for treating SBRT pancreas has resulted in an approach tailored to individual patient’s motion management needs and prepared us for future technological innovations.

Stereotactic body radiation therapy in cholangiocarcinoma: a systematic review.

Stereotactic body radiation therapy (SBRT) has been used in the treatment of cholangiocarcinoma (CC) but toxicity and clinical results of SBRT in CC are still limited and sparse. Therefore, the aim of this systematic review was to analyze the results of SBRT in the setting of advanced CC. A systematic literature search was conducted on PubMed, Scopus, and Cochrane library using the PRISMA methodology. Studies including at least 10 patients with diagnosis of advanced CC regardless of tumor site and other treatments were included. The primary outcome was overall survival (OS) and secondary endpoints were local control (LC) and toxicity rates. The ROBINS-I risk of bias tool was used. 10 studies (231 patients) fulfilled the selection criteria and were included in this review. All but one study showed moderate to serious risk of bias. Median follow up was 15 months (range: 7.8-64.0 months). Pooled 1 year OS was 58.3% (95% CI: 50.2-66.1%) and pooled 2 year OS was 35.5% (95% CI: 22.1-50.1%). Pooled 1 year LC was 83.4%, (95% CI: 76.5-89.4%). The reported toxicities were acceptable and manageable with only one treatment-related death. The role of SBRT in CC is not yet supported by robust evidence in literature. However, within this limit, preliminary results seem almost comparable to the ones of standard chemotherapy or chemoradiation. SBRT seems effective in terms of LC with acceptable treatment-related toxicities. Therefore, SBRT can be considered a therapeutic option at least in selected patients with CC, possibly combined with adjuvant chemotherapy (CHT).

Emerging Role of Stereotactic Body Radiotherapy

Emerging Role of Stereotactic Body Radiotherapy

177. Feasibility of SBRT-VMAT as an alternative to HDR brachytherapy for vaginal cuff. A dosimetric study

PurposeWe evaluate the role of stereotactic body radiotherapy (SBRT) using VMAT technique as an alternative to high-dose rate brachytherapy (HDR-BRT) in the treatment of vaginal cuff in postoperative endometrial cancer. MethodsCT scans of 5 patients were used in this study. The CTV was defined as the 0.5 cm tissue around the applicator (then subtracting the applicator). Total dose was 30 Gy delivered in 5 fractions. In HDR-BRT, dose was prescribed at a distance of 0.5 cm from the surface applicator. For VMAT diation, a PTV was obtained from CTV by an expansion of 3 mm. Two VMAT plans were generated using a full arc rotation. The first plan was optimized with an anatomy-based optimization module (AB_VMAT) using a 1 mm MLC beam margin to enhance dose fallout. The second plan was generated with a full-inverse planning module (FI_VMAT). Conformity (CI100, CI50), gradient (GI), homogeneity (HI) indexes and equivalent uniform dose (EUD) were calculated. A Kruskal-Wallis ANOVA was performed. ResultsVMAT plans provided targets coverage comparable with HDR (p < 0.05). Dose distributions were more heterogeneous with HDR: Dmean were 144.2% for CTV in HDR and 118.0 and 109.1% for PTV in AB_VMAT and FI_VMAT, respectively. The mean values of EUD for CTV were: HDR 40.9 Gy; AB_VMAT 39.0 Gy; FI_VMAT 33.3 Gy. GI indexes were 2.81, 3.37 and 4.15 for HDR, AB_VMAT and FI_VMAT, respectively. Dmean and maximal doses to 2 cc for rectum and bladder were lower in HDR-BRT plans compared to AB_VMAT and FI:VMAT (rectum Dmean: 39.8% vs 47.4% and 53.0%; bladder Dmean: 35.4% vs 40.4% and 46.1%; rectum D2cc: 104.8% vs 108.0% and 116.2%; bladder D2cc: 86.64% vs 94.0% and 100.0%). ConclusionsHDR-BRT provided superior dose distribution with respect to VMAT. AB_VMAT plans tend to better mimic the HDR dose distribution, providing a fast, safe and reasonable alternative.