Prospective study on stereotactic body radiotherapy for small pancreatic neuroendocrine tumors: tolerance and effectiveness analysis.

INTRODUCTION: Surgery is the standard treatment for pancreatic neuroendocrine tumors (pNETs), obtaining favorable results but associating high morbidity and mortality rates. This study assesses stereotactic body radiation therapy (SBRT) as a radical approach for small (< 2 cm) nonfunctioning pNETs. MATERIALS AND METHODS: From January 2017 to June 2023, 20 patients with small pNETs underwent SBRT in an IRB-approved study. Endpoints included local control, tolerance, progression-free survival, and overall survival (OS). Diagnostic assessments comprised endoscopy, CT scans, OctreScan or PET-Dotatoc, abdominal MRI, and histological confirmatory samples. RESULTS: In a 30-month follow-up of 20 patients (median age 55.5 years), SBRT was well-tolerated with no grade > 2 toxicity. 40% showed morphological response, 55% remained stable. Metabolically, 50% achieved significant improvement. With a median OS of 41.5 months, all patients were alive without local or distant progression or need for surgical resection. CONCLUSION: SBRT is a feasible and well-tolerated approach for small neuroendocrine pancreatic tumors, demonstrating effective local control. Further investigations are vital for validation and extension of these findings.

Clinical effects of re-evaluating a lung SBRT failure mode and effects analysis in a radiotherapy department.

PURPOSE: The increasing complexity of radiation treatments can hinder its clinical success. This study aimed to better understand evolving risks by re-evaluating a Failure Mode and Effects Analysis (FMEA) in lung SBRT. METHODS: An experienced multidisciplinary team conducted an FMEA and made a reassessment 3 years later. A process map was developed with potential failure modes (FMs) identified. High-risk FMs and their possible causes and corrective actions were determined. The initial FMEA analysis was compared to gain a deeper perspective. RESULTS: We identified 232 FMs. The high-risk processes were plan approval, target contouring, and patient evaluation. The corrective measures were based on stricter standardization of plan approval, pre-planning peer review, and a supporting pretreatment checklist, which substantially reduced the risk priority number in the revised FMEA. In the FMEA reassessment, we observed that the increased complexity and number of patients receiving lung SBRT conditioned a more substantial presence of human factors and communication errors as causal conditions and a potential wrong dose as a final effect. CONCLUSIONS: Conducting a lung SBRT FMEA analysis has identified high-risk conditions that have been effectively mitigated in an FMEA reanalysis. Plan approval has shown to be a weak link in the process. The increasing complexity of treatments and patient numbers have shifted causal factors toward human failure and communication errors. The potential of a wrong dose as a final effect augments in this scenario. We propose that digital and artificial intelligence options are needed to mitigate potential errors in high-complexity and high-risk RT scenarios.

SBRT-SG-01: final results of a prospective multicenter study on stereotactic body radiotherapy for liver metastases.

OBJECTIVE: This study aimed to assess the efficacy and tolerability of stereotactic body radiation therapy (SBRT) for the treatment of liver metastases. METHODS: Patients with up to 5 liver metastases were enrolled in this prospective multicenter study and underwent SBRT. Efficacy outcomes included in-field local control (LC), progression-free survival (PFS), and overall survival (OS). Acute and late toxicities were evaluated using CTCAE v.4.0. RESULTS: A total of 52 patients with 105 liver metastases were treated between 2015 and 2018. The most common primary tumor was colorectal cancer (72% of cases). Liver metastases were synchronous with the primary tumor diagnosis in 24 patients (46.2%), and 21 patients (40.4%) presented with other extrahepatic oligometastases. All patients underwent intensity-modulated radiation therapy (IMRT)/volumetric-modulated arc therapy (VMAT) with image-guided radiation therapy (IGRT) and respiratory gating, and a minimum biologically effective dose (BED10Gy) of 100 Gy was delivered to all lesions. With a median follow-up of 23.1 months (range: 13.4-30.9 months) since liver SBRT, the median actuarial local progression-free survival (local-PFS) was not reached. The actuarial in-field LC rates were 84.9% and 78.4% at 24 and 48 months, respectively. The median actuarial liver-PFS and distant-PFS were 11 and 10.8 months, respectively. The actuarial median overall survival (OS) was 27.7 months from SBRT and 52.5 months from metastases diagnosis. Patients with lesion diameter ≤ 5 cm had significantly better median liver-PFS (p = 0.006) and OS (p = 0.018). No acute or late toxicities of grade ≥ 3 were observed. CONCLUSIONS: This prospective multicenter study confirms that liver SBRT is an effective alternative for the treatment of liver metastases, demonstrating high rates of local control and survival while maintaining a low toxicity profile.

Biologically effective dose (BED) value lower than 120 Gy improve outcomes in lung SBRT.

BACKGROUND: Lung SBRT has a well-defined role in the treatment of patients with early stage non-small cell lung cancer who are not surgical candidates or refuse surgery. Biologically effective dose (BED) of greater than or equal to 100 Gy has been recommended. However, optimal fractionation remains unclear. Our objective was analyze patients treated with lung SBRT in our institution and evaluate outcomes according prescribed dose. PATIENTS AND METHODS: One hundred nine patients with early non-small cell lung cancer and treated with lung SBRT were retrospectively analyzed. Differences between dose received, local control, and survival were evaluated. For comparison of BEDs, the prescribed dose for SBRT was stratified according to two groups: high (BED > 120 Gy) and low (BED < 120 Gy). RESULTS: A relationship between mortality and total dose (54.7 Gy ± 4.8) was observed. Significantly worse survival was observed for patients with higher total doses (p < 0.003). It was found that patients receiving BED > 120 had increased mortality compared to patients receiving BED < 120 (p = 0.021). It was observed mean dose/fraction 12.6 Gy/f was a protective factor and decreased the probability of death. CONCLUSION: Our data suggest that mean total dose lower 54 and a calculated BED < 120 Gy is the optimal. Further prospective data are needed to confirm these results and determine the optimal dose fractionation scheme as a function of tumor size and location of volume.

Stereotactic body radiation therapy (SBRT) for spinal metastases: 12 years of a single center experience.

OBJECTIVE: To assess the clinical outcomes of patients with spine metastases treated with SBRT at our institution. MATERIALS AND METHODS: Patients with spine metastases treated with SBRT (1 fraction/18 Gy or 5 fractions/7 Gy) during the last 12 years have been analyzed. All patients were simulated supine in a vacuum cushion or with a shoulder mask. CT scans and MRI image registration were performed. Contouring was based on International Spine-Radiosurgery-Consortium-Consensus-Guidelines. Highly conformal-techniques (IMRT/VMAT) were used for treatment planning. Intra and interfraction (CBCT or X-Ray-ExacTrac) verification were mandatory. RESULTS: From February 2010 to January 2022, 129 patients with spinal metastases were treated with SBRT [1 fraction/18 Gy (75%) or 5 fractions/7 Gy] (25%). For patients with painful metastases (74/129:57%), 100% experienced an improvement in pain after SBRT. With a median follow-up of 14.2 months (average 22.9; range 0.5-140) 6 patients (4.6%) experienced local relapse. Local progression-free survival was different, considering metastases's location (p < 0.04). The 1, 2 and 3 years overall survival (OS) were 91.2%, 85.1% and 83.2%, respectively. Overall survival was significantly better for patients with spine metastases of breast and prostate cancers compared to other tumors (p < 0.05) and significantly worse when visceral metastases were present (p < 0.05), when patients were metastatic de novo (p < 0.05), and in those patients receiving single fraction SBRT (p: 0.01). CONCLUSIONS: According to our experience, SBRT for patients with spinal metastases was effective in terms of local control and useful to reach pain relief. Regarding the intent of the treatment, an adequate selection of patients is essential to propose this ablative approach.

Automated treatment planning for liver cancer stereotactic body radiotherapy.

PURPOSE: To evaluate the quality of fully automated stereotactic body radiation therapy (SBRT) planning based on volumetric modulated arc therapy, which can reduce the reliance on historical plans and the experience of dosimetrists. METHODS: Fully automated re-planning was performed on twenty liver cancer patients, automated plans based on automated SBRT planning (ASP) program and manual plans were conducted and compared. One patient was randomly selected and evaluate the repeatability of ASP, ten automated and ten manual SBRT plans were generated based on the same initial optimization objectives. Then, ten SBRT plans were generated for another selected randomly patient with different initial optimization objectives to assess the reproducibility. All plans were clinically evaluated in a double-blinded manner by five experienced radiation oncologists. RESULTS: Fully automated plans provided similar planning target volume dose coverage and statistically better organ at risk sparing compared to the manual plans. Notably, automated plans achieved significant dose reduction in spinal cord, stomach, kidney, duodenum, and colon, with a median dose of D2% reduction ranging from 0.64 to 2.85 Gy. R50% and Dmean of ten rings for automated plans were significantly lower than those of manual plans. The average planning time for automated and manual plans was 59.8 ± 7.9 min vs. 127.1 ± 16.8 min (- 67.3 min). CONCLUSION: Automated planning for SBRT, without relying on historical data, can generate comparable or even better plan quality for liver cancer compared with manual planning, along with better reproducibility, and less clinically planning time.

Local treatment in oligometastasis from breast cancer: an overview.

Oligometastasic breast cancer (OMBC) consists of breast cancer patient with a limited number of systemic metastases (≤ 5), all of them candidates for local ablative treatment with the intention of achieving long-term control of the metastasis and, eventually, an increase in survival The first consensus for the management of patients with oligometastatic breast cancer (OMBC) was published in 2007, establishing that a more aggressive multidisciplinary strategy is recommended in order to increase the survival while maintaining a good quality of life. The current scientific evidence is based on observational studies, mainly retrospective, systematic reviews and meta-analyses, and only a randomized nonexclusive study of oligometastatic (OM) published. All trials with Stereotactic Body Radiation Therapy (SBRT) in OM cancer have shown excellent tolerance and good local control, although first trials on Lung SBRT did not prove so excellent tolerance and had some deaths due to bronchus irradiation and secondary hemoptysis. There are multiple ongoing studies researching the benefit of SBRT in oligometastatic breast cancer. Despite the lack of impact on survival seen in the NRG BR-002 Trial, SBRT probably allows the delay of the systemic treatment until progression, and so, improves the quality of life of patients. We have to wait for the results of the ongoing and future studies for clarification of the role of local treatment in OMBC.

Ten-year experience of bone SBRT in breast cancer: analysis of predictive factors of effectiveness.

PURPOSE: Data on the benefit of stereotactic body radiation therapy (SBRT) in patients with breast cancer (BC) and bone metastases remain limited. The purpose of this study is to report our 10-year experience of bone SBRT, analyzing toxicity and prognostic factors for local control (LC); progression-free survival, and overall survival (OS). METHODS/PATIENTS: We analyzed all spine and non-spine bone SBRT performed in patients with BC during the 2012-2022 period at our institution. Treatments carried out with ablative intent in stereotactic conditions with dose/fraction ≥ 5 Gy in 5 or fewer sessions were considered. Demographic, treatment, and toxicity data were recorded according to CTCAEv4. Risk factors were assessed through univariate and multivariate analysis by Cox regression. RESULTS: 60 bone SBRT treatments were performed during the study period. 75% were spine SBRT and 25% were non-spine SBRT (median BED4Gy was 80 Gy4). The median age was 52.5 years (34-79). The median tumor volume was 2.9 cm3 (0.5-39.4). The median follow-up was 32.4 months (1.2-101.7). 1 and 2 years LC were 92.9 and 86.6%, respectively. 1 and 2 years OS were 100 and 90.6%, respectively. Multivariate analysis (MVA) associated volume of the treated lesion ≥ 13 cm3 with worse LC (p = 0.046; HR 12.1, 95%CI = 1.1-140.3). In addition, deferring SBRT > 3 months after lesion diagnosis to prioritize systemic treatment showed a significant benefit, improving the 2 years LC up to 96.8% vs. 67.5% for SBRT performed before this period (p = 0.031; HR 0.1, 95%CI = 0.01-0.8). Hormonal receptors, the total number of metastases, and CA15-3 value were significantly associated with OS in MVA. During follow-up, three non-spine fractures (5%) were observed. CONCLUSIONS: According to our data, bone SBRT is a safe and effective technique for BC. Upfront systemic treatment before SBRT offers a benefit in LC. Therefore, SBRT should be considered after prior systemic treatment in this population.

Metabolic response after 68Ga-PSMA-PET/CT-directed IGRT/SBRT for oligometastases prostate cancer.

BACKGROUND: We used 68Ga PSMA PET/CT in the current investigation to assess the metabolic response and local control of metastasis in patients with oligometastatic prostate cancer receiving SBRT. MATERIALS AND PROCEDURES: We performed a retrospective evaluation of the medical data of all patients with oligometastatic prostate cancer who underwent stereotactic body radiation therapy (SBRT) between 2017 and 2021. Our analysis only included medical records of patients who had SBRT for oligometastatic prostate cancer and had pre and post-SBRT 68Ga PSMA PET/CT images. Patient-related (age), disease-related (Gleason score, location of metastases), and treatment-related (factors and outcomes) data were collected from the medical files. RESULTS: A total of 17 patients (28 lesions) with a median age of 69 years were included in the research. A median follow-up of 16.6 months was used (range 6-36 months). The median follow-up period for 68 Ga PSMA PET/CT was 8 months (the range was 5-24 months). The median pre-treatment PSA level was 1.7 ng/mL (range 0.39-18.3 ng/mL) compared to the post-treatment PSA nadir of 0.05 ng/mL (0.02-4.57). During the follow-up period, local control was 96%, and there was a link between PSMA avidity on PET. In the treated lesions, there were no recurrences. During follow-up, none of the patients experienced toxicities of grade 3 or above. CONCLUSIONS: SBRT is a highly successful and safe way of treating patients with oligometastatic prostate cancer. Additional research is needed to examine 68Ga PSMA PET/CT to assess further for demarcation and follow-up.

Reirradiation on spine metastases: an Italian survey on behalf of palliative care and reirradiation study groups of Italian association of radiotherapy and clinical oncology (AIRO).

AIM: This survey derived from the collaboration between the Palliative Care and Reirradiation Study Groups of the Italian Association of Radiotherapy and Clinical Oncology (AIRO). Its aim was to obtain a real "snapshot" on the treatments of spinal metastases, focusing on reirradiation, among radiation oncologists in Italy. METHODS: The survey was elaborated on SurveyMonkey's online interface and was sent via e-mail to all Radiation Oncologists of AIRO that were invited to anonymously fill in the electronic form within 60 days. The questionnaire was prepared by the AIRO "Palliative care" and "Reirradiation" Study Groups and it consisted of 36 questions, 19 single-choice questions, 10 multiple-choice questions and 6 open questions. The data were analyzed and represented with tables and graphs. RESULTS: The survey shows that palliative radiotherapy remains a field of interest for most ROs in the Italian centers. 3D Conventional Radiation Therapy (3DCRT) alone or in combination with other techniques is the primary choice for patients with a life expectancy of less than 6 months. For patients with a life expectancy of more than six months, there is an increased use of new technologies, such as Volumetric Modulated Arc Therapy (VMAT). Factors considered for retreatment are time between first and second treatment, dose delivered to spine metastasis and spinal cord in the first treatment, vertebral stability, symptoms, and/or performance status. The most feared complication are myelopathy followed by vertebral fracture and local recurrence. This explain an increasing focus on patient selection and the use of high technology in the treatment of metastatic patients. CONCLUSION: Stereotactic body radiotherapy (SBRT) and image-guided radiotherapy allow the administration of ablative RT doses while sparing the constraints of healthy tissue in spinal metastases. However, there is still an unclear and heterogeneous reality in the reirradiation of spinal metastases. A national registry with the aim of clarifying the most controversial aspects of vertebral metastasis retreatments will enable better management of these patients and design more targeted study designs.

Unravelling oligometastatic disease from the perspective of radiation and medical oncology. Part II: prostate cancer and colorectal cancer.

Oligometastatic disease (OMD) defines a status of cancer that is intermediate between localized and widely spread metastatic disease, and can be treated with curative intent. While imaging diagnostic tools have considerably improved in recent years, unidentified micrometastases can still escape from current detection techniques allowing disease to progress. The variety of OMD scenarios are mainly defined by the number of metastases, the biological and molecular tumour profiles, and the timing of the development of metastases. Increasing knowledge has contributed to the earlier and improved detection of OMD, underlining the importance of an early disease control. Based on increasing detection rates of OMD in the current real clinical practice and the lack of standardized evidence-based guidelines to treat this cancer status, a board of experts from the Spanish Societies of Radiation Oncology (SEOR) and Medical Oncology (SEOM) organized a series of sessions to update the current state-of-the-art on OMD from a multidisciplinary perspective, and to discuss how results from clinical studies may translate into promising treatment options. This experts' review series summarizes what is known and what it is pending clarification in the context of OMD in the scenarios of Non-Small Cell Lung Cancer and Breast Cancer (Part I), and Prostate Cancer and Colorectal Cancer (Part II), aiming to offer specialists a pragmatic framework that might contribute to the improved management of patients.

Unravelling oligometastatic disease from the perspective of radiation and medical oncology. Part I: non-small cell lung cancer and breast cancer.

Oligometastatic disease (OMD) defines a cancer status that is intermediate between localized and widely spread metastatic disease, and can be treated with curative intent. While diagnostic imaging tools have considerably improved in recent years, unidentified micrometastases can still evade current detection techniques, allowing the disease to progress. The various OMD scenarios are mainly defined by the number of metastases, the biological and molecular tumour profiles, and the timing of the development of metastases. Increasing knowledge has contributed to the earlier and improved detection of OMD, underlining the importance of early disease control. In view of increasing OMD detection rates in current real-world clinical practice and the lack of standardized evidence-based guidelines to treat this cancer status, a board of experts from the Spanish Societies of Radiation Oncology (SEOR) and Medical Oncology (SEOM) organized a series of sessions to update the current state-of-the-art on OMD from a multidisciplinary perspective, and to discuss how results from clinical studies might translate into promising treatment options. This expert review series summarizes what is known and what it is pending clarification in the context of OMD in the scenarios of non-small cell lung cancer and breast cancer (Part I), and prostate cancer and colorectal cancer (Part II), aiming to offer specialists a pragmatic framework to help improve patient management.

Race is a Risk Factor for the Deferral of Resection and Radiation for Early-Stage Lung Cancer.

PURPOSE: There remain profound race-related disparities in the treatment of non-small cell lung cancer (NSCLC). Deferral of operative management for early-stage disease is recognized as driver of this disparity. Black race has been associated with higher rates of surgical deferral. It remains unclear how race impacts likelihood of receiving radiation therapy after declining surgical management of NSCLC. PATIENTS AND METHODS: A retrospective cohort analysis was completed using data from the National Cancer Database (NCBD) for patients 18 and over with stage I NSCLC offered surgical resection from 2004 to 2015 (N = 89,462). Multivariable logistic regression identified predictors of surgical deferral and predictors for deferral of radiation after deferral of surgery. Kaplan-Meier survival analysis with log-rank tests and multivariable Cox proportional hazards regressions were performed. RESULTS: 87,293 (97.6%) patients underwent surgery, 2169 (2.4%) deferred. Patients who deferred had 2.1 times higher hazard ratio for mortality, (HR = 2.08, [1.97, 2.29], P < .001). Of those that deferred, 1250 (57.6%) received postdeferral radiation. Compared to White patients, Black patients had OR of 1.82 for deferring both surgery and radiation (aOR: 1.82, [1.31, 2.53], P < .001) and Asian and Pacific Island (API) patients had an OR of 2.67 (aOR: 2.67, [1.27, 4.64], P = .008). Other predictors of deferral of therapy included: Medicare or lack of insurance, and treatment at nonacademic medical centers. CONCLUSION: Insurance status and Black race, and API race are associated with deferring surgical therapy and radiation therapy for NSCLC. These findings are consistent with the large body of work showing worse outcomes for treatment of NSCLC in minority patients.

Impact of stereotactic body radiotherapy vs palliative radiotherapy on oncologic outcomes of patients with metastatic kidney cancer concomitantly treated with immune checkpoint inhibitors: a preliminary, multicentre experience.

PURPOSE: To explore the benefit yielded by radiotherapy (RT), we report a series of metastatic renal cell carcinoma (RCC) patients treated with concomitant RT plus Nivolumab. METHODS/PATIENTS: Patients undergoing Nivolumab treatment plus concomitant RT (ablative or palliative) were included. RT was defined Ablative if >5 Gy/fraction were delivered. RESULTS: Ablative RT intent was the only independent predictor of both progression free and overall survival (HR 3.51, 95% CI 1.6-7.5, p = 0.0012 and HR 2.8, 95% CI 0.99-8.07, p = 0.05, respectively). CONCLUSION: Ablative RT may improve oncologic outcomes in selected patients with metastatic RCC treated with Nivolumab as compared to palliative RT.

Applying PET-CT for predicting the efficacy of SBRT to inoperable early-stage lung adenocarcinoma: A Brazilian case-series.

Background: Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage inoperable primary lung cancer. Here we report a thorough description of the prognostic value of pre-SBRT SUVmax for predicting the efficacy of SBRT in early-stage lung adenocarcinoma. Methods: This is a retrospective study of consecutive cases of early-stage inoperable lung adenocarcinoma, staged with PET-CT, treated with SBRT between 2007 and 17. Kaplan-Meier (KM) curves were used to assess overall survival and compare time to event between those with PET-CT SUVmax values ≤ 5.0 and those > 5. Fisher's Exact tests and the Mann-Whitney U were used to compare the patient and clinical data of those with SUVmax≤5.0 and >5.0, and those with and without any failure. Findings: Amongst 50 lung carcinoma lesions, from 47 patients (34 (68%)-T1a or 5 (p = 0.112). In addition, 5 experienced a regional failure and 4 a distant failure. Higher PET-CT SUVmax values before SBRT were associated with an increased risk of any failure (36% versus 0%, p = 0.0040 on Fisher's Exact test) and faster time to event (p = 0.010, log rank test). Both acute and late toxicities profile were acceptable. Interpretation: Patients with early-stage inoperable lung adenocarcinoma present good clinical outcomes when treated with SBRT. We raised the hypothesis that the value of PET-CT SUVmax before SBRT may be an important predictive factor in disease control. Funding: None.

SEOR SBRT-SG stereotactic body radiation therapy consensus guidelines for non-spine bone metastasis.

The use of stereotactic body radiation therapy (SBRT) to treat non-spine bone metastases (NSBM) is becoming increasingly common in clinical practice. The clinical advantages of SBRT include good pain control and high local control rates, although only limited data are available. The Spanish Society of Radiation Oncology (SEOR) SBRT group recently convened a task force of experts in the field to address key questions related to SBRT for NSBM, including treatment indications, planning, techniques, and dose fractionation. The task force reviewed the available literature to develop evidence-based recommendations for the safe application of NSBM SBRT and to standardize and optimize SBRT processes. The present document provides a comprehensive analysis of the available data, including ongoing clinical trials and controversies, providing clinically applicable recommendations.

Stereotactic body radiotherapy for early-stage non-small cell lung cancer: a multicentre study by the Oncologic Group for the Study of Lung Cancer (Spanish Radiation Oncology Society).

PURPOSE/OBJECTIVE(S): Stereotactic body radiotherapy (SBRT) has become the standard of care for patients with medically inoperable early-stage non-small cell lung cancer (NSCLC) and for patients who refuse surgery. The aim of this study was to evaluate the effectiveness and safety of primary SBRT in patients with early-stage NSCLC. MATERIALS/METHODS: Retrospective multicenter study of 397 patients (416 primary lung tumours) treated with SBRT at 18 centres in Spain. 83.2% were men. The median age was 74.4 years. In 94.4% of cases, the tumour was inoperable. The pathological report was available in 54.6% of cases. SPSS vs 22.0. was used to perform all statistical analyses. RESULTS: Complete response was obtained in 53.6% of cases. Significant prognostic factors were standard CT planning (p = 0.014) and 4D cone beam CT (p = 0.000). Acute and chronic toxicity ≥ grade 3 was observed in 1.2% of cases. At a median follow-up of 30 months, local relapse was 9.6%, lymph node relapse 12.8%, distant metastasis 16.6%, and another lung tumour 11.5%. Complete response was the only significant prognostic factor for local relapse (p = 0.012) and distant metastasis (p = 0.001). The local relapse-free survival was 88.7%. The overall survival was 75.7%. The cancer-specific survival was 92.7%. The disease-free survival was 78.7%. CONCLUSION: SBRT is an effective and well-tolerated treatment option for patients with early-stage lung cancer who are not suitable for surgery. The most important prognostic factor for local and distant recurrence was complete response, which in our sample depended on the type of CT planning and the IGRT technique.

Long-term outcomes of spinal SBRT. Is it important to select the treatment time?

PURPOSE: SBRT (stereotactic body radiation therapy) is widely used as a curative treatment in tumoral lesions and has become a fundamental tool for the treatment of spine metastasis. In this study, we present survival and toxicity outcomes of spine SBRT after a 2-year follow-up. METHODS/PATIENTS: Data from spine SBRT treatments performed at our institution between March 2012 and February 2020 was collected. Medical records, including demographic, primary tumor, and treatment characteristics were reviewed. Patient follow-up included clinical evaluation, imaging, and blood tests. Toxicity was recorded according to CTCAE v4.0. RESULTS: We analyzed 73 consecutive spine SBRT treatments in 60 patients. 39.7% of the cases had primary breast cancer and 23.3% had prostate cancer. Most cases (87.7%) were treated with a single SBRT fraction of 16 Gy. Median follow-up was 26.1 months (range 1.7-78.6), and 1- and 2-year overall survival (OS) rates were 96.9% and 84.2%, respectively. Local control (LC) rates at 1- and 2-years were 76.3% and 70.6%, respectively. Multivariate analysis identified histology as a prognostic factor for both OS and LC. Patients who underwent spine SBRT 6 months after the spinal lesion diagnosis had LC at 2 years of 88%, vs 61.7% for those who underwent SBRT before this period. No grade III or higher toxicity was reported. The vertebral compression fracture (VCF) rate was 4.1%. CONCLUSION: Spine SBRT at our institution showed a 2-year LC of 70.6%, without G3 toxicities. Delaying SBRT at least 6 months to administer systemic treatment was related to an improvement in local control.

Clinical verification of treatment planning dose calculation in lung SBRT with GATE Monte Carlo simulation code.

PURPOSE: This study aims to use GATE/Geant4 simulation code to evaluate the performance of dose calculations with Anisotropic Analytical Algorithm (AAA) in the context of lung SBRT for complex treatments considering images of patients. METHODS: Four cases of non-small cell lung cancer treated with SBRT were selected for this study. Irradiation plans were created with AAA and recalculated end to end using Monte Carlo (MC) method maintaining field configurations identical to the original plans. Each treatment plan was evaluated in terms of PTV and organs at risk (OARs) using dose-volume histograms (DVH). Dosimetric parameters obtained from DVHs were used to compare AAA and MC. RESULTS: The comparison between the AAA and MC DVH using gamma analysis with the passing criteria of 3%/3% showed an average passing rate of more than 90% for the PTV structure and 97% for the OARs. Tightening the criteria to 2%/2% showed a reduction in the average passing rate of the PTV to 86%. The agreement between the AAA and MC dose calculations for PTV dosimetric parameters (V100; V90; Homogeneity index; maximum, minimum and mean dose; CIPaddick and D2cm) was within 18.4%. For OARs, the biggest differences were observed in the spinal cord and the great vessels. CONCLUSIONS: In general, we did not find significant differences between AAA and MC. The results indicate that AAA could be used in complex SBRT cases that involve a larger number of small treatment fields in the presence of tissue heterogeneities.

5-year results of accelerated partial breast irradiation (APBI) with SBRT (stereotactic body radiation therapy) and exactrac adaptive gating (Novalis®) for very early breast cancer patients: was it all worth it?

PURPOSE: To explore the feasibility of image-guided and respiratory-gated Stereotactic Body Radiation Therapy (SBRT) for Accelerated Partial Breast Irradiation (APBI) in patients with very early breast cancer. MATERIAL AND METHODS: Selected patients with early breast carcinoma after breast-conserving surgery were enrolled in this phase II trial. A fiducial marker was percutaneously placed close to surgical bed and five external fiducials were set on the skin. A CT scan for planning was acquired at free breathing. The treatment was planned and DVH were assessed according to international recommendations. Prescription dose was 30 Gy in five consecutive fractions of 6 Gy. A 6MV monoenergetic LINAC (linear accelerator) that combines stereoscopic X-ray imaging system and ExacTrac Adaptive Gating technique was used. PTV (planning target volume) intrafraction motion was controlled and PTV was irradiated in a selected gated area of the respiratory cycle. Shifts for a correct, gated set-up were calculated and automatically applied. RESULTS: Between April 2013 and October 2015, a total of 23 patients were included. The median tumor size was 12 mm. The mean PTV volume was 114 cc. The mean ipsilateral lung V9 Gy was 2.2% and for left-sided breast cancers, the volume of the heart receiving 1.5 Gy was 11.5%. Maximum skin dose was 30.8 Gy. Acute toxicity was grade1 in all the patients and 100% experienced excellent/good breast cosmesis outcomes. With a median follow-up of 66 months (range 8-99 months) local-relapse-free-survival reaches 100%. One patient developed a second breast cancer outside the treated quadrant after 25.1 months. CONCLUSION: APBI with SBRT and ExacTrac Adaptive Gating System was feasible. The acute and late toxicities were almost null and cosmesis was excellent. We also found that the margins of 5 mm applied from CTV to PTV were sufficient to compensate for geometric uncertainties.