Practice Of Stereotactic Body Radiotherapy Research Articles

Stereotactic body radiotherapy for non-spine bone metastases: A meta-analysis and international stereotactic radiosurgery society (ISRS) clinical practice guidelines.

While SBRT to NSBM has become common, particularly in the oligometastatic population, the approach to treating non-spine bone metastases (NSBM) with stereotactic body radiotherapy (SBRT) varies widely across institutions and clinical trial protocols. We present a comprehensive systematic review of the literatures to inform practice recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS). A systematic literature review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies with at least 10 patients receiving SBRT for NSBM were identified and meta-analyses were completed to estimate pooled local control and overall survival rates. Published guidelines on NSBM SBRT were reviewed and consolidated. There were 25 studies included for qualitative analysis and 18 studies for quantitative analysis consisting of 13 retrospective studies, 2 non-randomized prospective studies, 1 randomized phase 2/3 trial, and a subgroup analysis of a phase I trial. The pooled local control rates at 1 and 2 years were 95 % (95 % CI: 89 %-98 %) and 94 % (95 % CI: 86 %-98 %), respectively. Pooled overall survival rates at 1 year and 2 years were 84 % (95 % CI: 73 %-91 %) and 81 % (95 % CI: 45 %-95 %), respectively. Consensus was reached on recommendations to inform treatment simulation, target delineation, dose fractionation, and anatomic site-specific recommendations. We present ISRS-endorsed consensus recommendations to inform best practice of SBRT to NSBM, which we found to be efficacious and associated with low rates of adverse events.

Stereotactic body radiotherapy for spinal oligometastases: a survey on patterns of practice on behalf of the Italian Association of Clinical Oncology and Radiotherapy (AIRO).

The Study Group for the Biology and Treatment of the OligoMetastatic Disease on behalf of the Italian Association of Radiotherapy and Clinical Oncology (AIRO) has conducted a national survey with the aim to depict the current patterns of practice of stereotactic body radiotherapy (SBRT) for spinal oligometastases. The Surveymonkey platform was used to send a 28-items questionnaire focused on demographic, clinical and technical aspects related to SBRT for spinal oligometastases. All the AIRO members were invited to fill the questionnaire. Data were then centralized to a single center for analysis and interpretation. 53 radiation oncologists from 47 centers fulfilled the survey. A complete agreement was observed in proposing SBRT for spinal oligometastases, with the majority considering up to 3 concurrent spine oligometastases feasible for SBRT (73.5%), regardless of spine site (70%), vertebral segment (85%) and morphological features of the lesion (71.7%). Regarding dose prescription, fractionated regimens resulted as the preferred option, either in 3 (58.4%) or five sessions (34%), with a substantial agreement in applying a PTV-margin larger than 1mm (almost 90% of participants), and ideally using both MRI and PET imaging to improve target volume and organs-at-risk delineation (67.9%). This national italian survey illustrates the patterns of practice and the main issues for the indication of SBRT for spinal oligometastases. A substantial agreement in the numerical cut-off and vertebral segment involved for SBRT indication was reported, with a slight heterogeneity in terms of dose prescription and fractionation schemes.

Stereotactic Body Radiotherapy as a Curative Treatment for De Novo Mucosal Carcinoma of the Head and Neck: A Feasible Alternative Option for Fragile Patients with Small Lesion: A Systematic Review.

Stereotactic body radiotherapy (SBRT) is characterized by a high dose per fraction, well-defined small targets, superior dose conformity, and a steep off-target dose gradient. A literature search was conducted to examine the experience with SBRT as a curative treatment for newly diagnosed mucosal carcinoma of the head and neck (MCHN). Four retrospective case series and one prospective phase I clinical trial published between 2012 and 2020 described 124 patients. SBRT was mainly performed in older patients with different tumor sites. The median size of the planning target volumes ranged from 5.3 to 41 cm3. Different approaches were used to create margins. In two studies, limited elective nodal irradiation was performed. The equivalent doses used were 60-83.33 Gy delivered in five fractions. Considerable heterogeneity was observed in the radiation dose specification. The incidence of grade ≥3 late toxicity was 0-8.3%, with local and regional control ranging from 73% to 100%. Improved or stable quality of life after SBRT was reported in two studies. Curative-intent SBRT for de novo MCHN appears to be an effective and relatively safe treatment for small tumor targets, preferably without concomitant elective tissue irradiation. Standardization of SBRT practice and well-designed prospective clinical trials are needed to better define the role of SBRT in this setting.

ESTRO clinical practice guideline: Stereotactic body radiotherapy for spine metastases

Background and purposeRecent progress in diagnostics and treatment of metastatic cancer patients have improved survival substantially. These developments also affect local therapies, with treatment aims shifting from short-term palliation to long-term symptom or disease control. There is consequently a need to better define the value of stereotactic body radiotherapy (SBRT) for the treatment of spinal metastases. MethodsThis ESTRO clinical practice guideline is based on a systematic literature review conducted according to PRISMA standards, which formed the basis for answering four key questions about the indication and practice of SBRT for spine metastases. ResultsThe analysis of the key questions based on current evidence yielded 22 recommendations and 5 statements with varying levels of endorsement, all achieving a consensus among experts of at least 75%. In the majority, the level of evidence supporting the recommendations and statements was moderate or expert opinion, only, indicating that spine SBRT is still an evolving field of clinical research. Recommendations were established concerning the selection of appropriate patients with painful spine metastases and oligometastatic disease. Recommendations about the practice of spinal SBRT covered technical planning aspects including dose and fractionation, patient positioning, immobilization and image-guided SBRT delivery. Finally, recommendations were developed regarding quality assurance protocols, including description of potential SBRT-related toxicity and risk mitigation strategies. ConclusionsThis ESTRO clinical practice guideline provides evidence-based recommendations and statements regarding the selection of patients with spinal metastases for SBRT and its safe implementation and practice. Enrollment of patients into well-designed prospective clinical trials addressing clinically relevant questions is considered important.

Stereotactic body radiotherapy in the management of hepatocellular carcinoma: An Australian multi-institutional patterns of practice review.

Stereotactic body radiotherapy (SBRT) is an emerging, therapeutic option in the management of hepatocellular carcinoma (HCC). A multicentre Liver Ablative Stereotactic Radiation (LASR) database was established to provide a collaborative platform for Australian institutions to define the practice of liver SBRT for HCC. This study explores the patterns of SBRT practice amongst Australian institutions. This was a multi-institutional retrospective study of patients treated with SBRT for HCC at 10 institutions between January 2013 and December 2019. Patients' demographics, disease characteristics and SBRT details were evaluated. Three hundred and seventeen patients were evaluated with a median age of 67years (range, 32-90). Liver cirrhosis was present in 88.6%, baseline Child-Pugh score was A5/6 in 85.1% and B7/8 in 13.2%. Median size of HCC treated was 30mm (range, 10-280). 63.1% had early-stage disease (Barcelona clinic liver cancer (BCLC) stage 0/A) and 36% had intermediate/advanced-stage disease (BCLC B/C). In 2013/2014, six courses of SBRT were delivered, increasing to 108 in 2019. SBRT was prescribed in five fractions for 71.3% of the cohort. The most common dose fractionation schedule was 40Gy in five fractions (24.3%). Median biologically effective dose (BED10 ) delivered was 85.5Gy for early-stage and 60Gy for intermediate/advanced disease, respectively. The most common prescription range was 100-120Gy BED10 (32.8%). SBRT utilisation for HCC is increasing in Australia. There was wide variation in size of tumours and disease stages treated, and prescription patterns. Uniform reporting of clinical and dosimetric details are important in refining the role of liver SBRT.

A survey of the practice of stereotactic body radiotherapy for hepatocellular and pancreatic malignancies in India.

Stereotactic body radiotherapy (SBRT) is increasingly being performed for hepatocellular cancer and liver metastases. The purpose of this study was to review the practice of SBRT for hepatocellular, pancreatic cancer and liver metastases in India. A survey comprising of 25 questions was designed and served to radiation oncology professionals at two major conferences. The survey consisted of 25 multiple choice questions on SBRT infrastructure and caseload, simulation methods and immobilizations, organ motion control methods, simulation and delivery, indications of liver and pancreatic SBRT and prescribed dose. The responses were analyzed using descriptive statistics. From January to June 2017, about 200 professionals were approached and 71 professionals responded with a response rate of 35.5%. The duration of the SBRT practice among respondents was less than 3 years in 53% with 32% having formal training in SBRT. The most common sites for the use of SBRT were lung and brain followed by liver and spine. Liver SBRT was practiced by 29 (59.2%) for hepatic oligometastases, hepatocellular carcinoma (HCC), and cholangiocarcinoma. The most common fractionation used was 50-60 Gy/6 fractions and 45 Gy/3 fractions. Pancreatic SBRT was practiced by 37%, mostly for medically inoperable or locally advanced pancreatic cancer. SBRT was not practiced by 22 (31%) of the respondents, and the main reasons were lack of infrastructure and structured training. The SBRT for liver has increased with a usage rate of over 50% amongst respondents. Pancreatic SBRT use is infrequent and limited to inoperable or advanced cases. Lack of infrastructure and training are the main challenges in the routine adaptation of SBRT.

Variation in current prescription practice of stereotactic body radiotherapy for peripherally located early stage non-small cell lung cancer: Recommendations for prescribing and recording according to the ACROP guideline and ICRU report 91

Background and purposeIn 2017 the ACROP guideline on SBRT for peripherally located early stage NSCLC was published. Later that year ICRU-91 about prescribing, recording and reporting was published. The purpose of this study is to quantify the current variation in prescription practice in the institutions that contributed to the ACROP guideline and to establish the link between the ACROP and ICRU-91 recommendations. Material and methodsFrom each of the eight participating centres, 15 SBRT plans for stage I NSCLC were analyzed. Plans were generated following the institutional protocol, centres prescribed 3 × 13.5 Gy, 3 × 15 Gy, 3 × 17 Gy or 3 × 18 Gy. Dose parameters of the target volumes were reported as recommended by ICRU-91 and also converted to BED10Gy. ResultsThe intra-institutional variance in D98%, Dmean and D2% of the PTV and GTV/ITV is substantially smaller than the inter-institutional spread, indicating well protocollised planning procedures are followed. The median values per centre ranged from 56.1 Gy to 73.1 Gy (D2%), 50.4 Gy to 63.3 Gy (Dmean) and 40.5 Gy to 53.6 Gy (D98%) for the PTV and from 57.1 Gy to 73.6 Gy (D2%), 53.7 Gy to 68.7 Gy (Dmean) and 48.5 Gy to 62.3 Gy (D98%) for the GTV/ITV.Comparing the variance in PTV D98% with the variance in GTV Dmean per centre, using an F-test, shows that four centres have a larger variance in GTV Dmean, while one centre has a larger variance in PTV D98% (p values <0.01). This shows some centres focus on achieving a constant PTV coverage while others aim at a constant GTV coverage. ConclusionMore detailed recommendations for dose planning and reporting of lung SBRT in line with ICRU-91 were formulated, including a minimum PTV D98% of 100 Gy BED10Gy and minimum GTV/ITV mean dose of 150 Gy BED10Gy and a D2% in the range of 60–70 Gy.

Pitfalls in lung stereotactic body radiotherapy—a review of organ toxicities and dose constraints

Stereotactic body radiotherapy (SBRT), which is also known as stereotactic ablative radiotherapy (SABR) has been established as a treatment for early-stage inoperable non-small cell lung cancer (NSCLC) in several international guidelines. One of the earliest phase I study data in lung SBRT was first published in 2003 by Timmerman and colleagues, with the same group subsequently reporting excellent phase II results. These two trials and similar landmark studies, now form the basis for lung SBRT practice internationally. Although SBRT is a standard treatment option for early stage inoperable NSCLC, it is still not available in many developing parts of the world. Because of its noninvasive nature, excellent control outcomes and safe track record. The indications for its use are expanding with more sites being treated as well as increasing use in early stage operable lung tumours and oligometastatic setting. There are still uncertainties with regards to optimal radiotherapy dose-fractionation regimen and because of the large ablative doses used in SBRT, there is a potential for significant side effects. Certain scenarios like treatment of central or recurrent tumors require greater care. In this paper, we elaborate on the common toxicities reported in literature in relation to SBRT of lung tumors as well as factors that may alter these risks.

주요간문맥종양혈전을 동반한 간세포암에 대한 다기관 체부정위방사선치료계획 비교연구(KROG 16-17)

Background/Aims: To evaluate the technical feasibility of stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma (HCC) with the major portal vein tumor thrombosis (PVTT). Methods: Ten institutions affiliated with the Korean Stereotactic Radiosurgery Group were provided the contours of four cases: the first case was the first branch PVTT with sufficient normal liver volume (NLV), the second was the first branch PVTT with insufficient NLV, the third was the main trunk PVTT at confluence level, and the fourth was the main trunk PVTT with entire length. The institutions were asked to make SBRT plans according to their current treatment protocols and to complete facility questionnaires. Results: Based on institutional protocols, SBRT was feasible in nine institutions for the first case (32-60 Gy in 3-5 fractions), in eight institutions for the second case (32-50 Gy in 3-5 fractions), in seven institutions for the third case (35-60 Gy in 3-5 fractions), and in four institutions for the fourth case (35-42 Gy in 4-5 fractions). The other institutions recommended hypo- or conventional fractionation due to insufficient NLV or gastrointestinal organ proximity. With analysis of the SBRT dose to the central hepatobiliary tract, the major PVTT could theoretically be associated with a high risk of hepatobiliary toxicity. Conclusions: Although SBRT is a technically feasible option for HCC with the major PVTT, there was a variability among the participating institutions. Therefore, further studies will be necessary to standardize the practice of SBRT for the major PVTT. (J Liver Cancer 2018;18:130-141)

Factors affecting local control of pulmonary oligometastases treated with stereotactic body radiotherapy

Background: Oligometastases refers to a state of limited metastatic disease. The use of local ablative therapies to patients with oligometastases can result in durable state of remission or long-term cure. Stereotactic body radiotherapy (SBRT) is a highly conformal radiation technique that delivers ablative doses to the target. The study aimed to evaluate local control (LC) and identify factors associated with poor LC in patients with pulmonary oligometastases treated with SBRT. Primary endpoint of the study was to assess LC; secondary endpoint was to determine factors associated with LC.Material and methods: Criteria used for selection of patients with oligometastases included: metastatic disease limited to a maximum of two organs and no more than five metastatic lesions at time of treatment. Peripheral tumors were treated with 51–60 Gy in three fractions or a single fraction of 30 Gy. Central tumors received a dose of 45–60 Gy in 5–8 fractions.Results: In 206 patients, 327 pulmonary oligometastases were treated with SBRT. Median follow-up was 22 months (range 2–100). LC at 2 and 3 years was 85% and 83%, respectively. On univariate analysis, biological equivalent dose assuming an α/β ratio of 10 (BED10) < 100 Gy (HR 3.09), single-fraction SBRT (HR 2.83), synchronous metastasis (HR 1.99), and pre-SBRT chemotherapy (HR 2.79) were significantly associated with inferior LC. In the multivariable analysis BED10 <100 Gy (HR 3.59), pre-SBRT chemotherapy (HR 2.61) and presence of synchronous metastasis (HR 2.21) remained independently associated with poor LC.Conclusions: SBRT achieved an excellent LC of 85% at 2 years. Although retrospective in nature, our study identified three factors associated with inferior LC. These factors may help to refine SBRT practice for pulmonary oligometastases in the future.

Definitive Stereotactic Body Radiotherapy (SBRT) for Extracranial Oligometastases: An International Survey of >1000 Radiation Oncologists.

Stereotactic body radiotherapy (SBRT) is often used to treat patients with oligometastases (OM). Yet, patterns of SBRT practice for OM are unknown. Therefore, we surveyed radiation oncologists internationally, to understand how and when SBRT is used for OM. A 25-question survey was distributed to radiation oncologists. Respondents using SBRT for OM were asked how long they have been treating OM, number of patients treated, organs treated, primary reason for use, doses used, and future intentions. Respondents not using SBRT for OM were asked reasons why SBRT was not used and intentions for future adoption. Data were analyzed anonymously. We received 1007 surveys from 43 countries. Eighty-three percent began using SBRT after 2005 and greater than one third after 2010. Eighty-four percent cited perceived treatment response/durability as the primary reason for using SBRT in OM patients. Commonly treated organs were lung (90%), liver (75%), and spine (70%). SBRT dose/fractionation schemes varied widely. Most would offer a second course to new OM. Nearly all (99%) planned to continue and 66% planned to increase SBRT for OM. Of those not using SBRT, 59% plan to start soon. The most common reason for not using SBRT was lack of clinical efficacy (48%) or lack of necessary image guidance equipment (34%). Radiation oncologists are increasingly using SBRT for OM. The main reason for not using SBRT for OM is a perceived lack of evidence demonstrating clinical advantages. These data strengthen the need for robust prospective clinical trials (ongoing and in development) to demonstrate clinical efficacy given the widespread adoption of SBRT for OM.

ESTRO ACROP consensus guideline on implementation and practice of stereotactic body radiotherapy for peripherally located early stage non-small cell lung cancer

BackgroundStereotactic body radiotherapy (SBRT) has become the standard of care for medically inoperable patients with peripherally located, early stage non-small cell lung cancer (NSCLC), and for those refusing surgical resection. Despite the availability of national and international guidelines, there exists substantial variability in many aspects of SBRT practice. MethodsThe ESTRO ACROP guideline is based on a questionnaire covering all aspects of SBRT implementation and practice (n=114 items). The questionnaire was answered by the 11 faculty members of the ESTRO course “Clinical practice and implementation of image-guided SBRT” and their 8 institutions. ResultsAgreement by >50% of the institutions was achieved in 72% of all items. Only 8/57 technologies and techniques were identified as mandatory for SBRT while 32/57 were considered as optional. In contrast, quality-assurance related elements were considered as mandatory in 12/24 items. A consensus of risk-adapted SBRT fractionation was achieved with 3×15Gy for peripherally located lesions and 4×12Gy (PTV D95-D99; Dmax <125% to <150%) for lesions with broad chest wall contact. For patients free from severe comorbidities and with favourable long-term OS expectancy, use of the maximum tolerated dose of 3×18Gy should be considered. ConclusionsThis ACROP guideline achieved detailed recommendations in all aspects of SBRT implementation and practice, which will contribute to further standardization of SBRT for peripherally located early stage NSCLC.

Survey of current practices from the International Stereotactic Body Radiotherapy Consortium (ISBRTC) for head and neck cancers.

To provide a multi-institutional description of current practices of stereotactic body radiotherapy (SBRT) for head and neck cancer. 15 international institutions with significant experience in head and neck SBRT were asked to complete a questionnaire covering clinical and technical factors. SBRT is used 10-100% of the time for recurrent primary head and neck cancer, and 0-10% of the time in newly diagnosed disease. Five centers use a constraint for primary disease of 3-5 cm and 25-30 cc. Nine institutions apply a clinical target volume expansion of 1-10 mm and 14 use a planning target volume margin of 1-5 mm. Fractionation regimens vary between 15 and 22 Gy in 1 fraction to 30-50 Gy in 5 or 6 fractions. The risk of carotid blowout quoted in the re-irradiation setting ranges from 3 to 20%. There is considerable heterogeneity in patient selection and techniques in head and neck SBRT practice among experienced centers.

Stereotactic body radiotherapy for renal cell cancer and pancreatic cancer : Literature review and practice recommendations of the DEGRO Working Group on Stereotactic Radiotherapy.

This report of the Working Group on Stereotactic Radiotherapy of the German Society of Radiation Oncology (DEGRO) aims to provide aliterature review and practice recommendations for stereotactic body radiotherapy (SBRT) of primary renal cell cancer and primary pancreatic cancer. Aliterature search on SBRT for both renal cancer and pancreatic cancer was performed with focus on prospective trials and technical aspects for clinical implementation. Data on renal and pancreatic SBRT are limited, but show promising rates of local control for both treatment sites. For pancreatic cancer, fractionated SBRT should be preferred to single-dose treatment to reduce the risk of gastrointestinal toxicity. Motion-compensation strategies and image guidance are paramount for safe SBRT delivery in both tumor entities. SBRT for renal cancer and pancreatic cancer have been successfully evaluated in phaseI and phaseII trials. Pancreatic SBRT should be practiced carefully and only within prospective protocols due to the risk of severe gastrointestinal toxicity. SBRT for primary renal cell cancer appears aviable option for medically inoperable patients but future research needs to better define patient selection criteria and the detailed practice of SBRT.

Stereotactic body radiation for pancreatic cancer: results of an international survey of practice patterns

Stereotactic body radiotherapy (SBRT) is an emerging treatment option for borderline resectable and locally advanced, unresectable pancreatic cancer (PCA). However, no standardized guidelines for treatment exist and patterns of SBRT use for PCA are unclear. Radiation oncologists known to use SBRT in the setting of PCA were invited to complete a 26-item Web-based survey on practice patterns. Thirty of the 36 (83 %) invited radiation oncologists completed the survey. Of the responders, 86 % treat with 6–8 Gy ×5 fractions. The majority (93 %) of responders use four-dimensional computed tomography (4D-CT) for simulation, with 50 % using gating for breathing motion. Two thirds of radiation oncologists use fiducials for tumor localization. Most (79 %) responders noted an improvement in patient-reported pain after SBRT. Approximately, 59 % report difficulty obtaining insurance clearance for pancreas SBRT in the absence of a clinical trial. The largest variations in practice were related to gross tumor volume (GTV) to planning target volume (PTV) expansions and management of respiratory motion. SBRT is increasingly used for PCA. The data presented here indicate that the majority of radiation oncologists treat with 6–8 Gy ×5 fractions and use fiducials with 4D-CT simulation for localization and planning. Although the majority of the surveyed physicians prefer SBRT to standard radiation, it may be underutilized due to the difficulty of obtaining insurance approval outside of a clinical trial. Our investigation documents current pancreas SBRT practice patterns and highlights the need for prospective clinical trials as a means to develop consensus guidelines for this emerging treatment.

Practice of stereotactic body radiotherapy in a developing country: Perception, aspiration, and limitation - A survey.

Stereotactic body radiotherapy (SBRT) is an effective and established modern technology now used more commonly. Radiation oncology personnel's (ROP) opinion toward SBRT in the developing countries like India is unknown. A 30 question survey evaluating ROP's profile, technological details, and SBRT's perceptive were seeked. Tata Memorial Center - ROP's email database was used. Survey questionnaire was emailed to 500 ROP's and 224 ROP's were contactable. Majority of the responders were from corporate hospitals and half of responders had experience of 5 or more years of experience in radiation oncology. SBRT was practiced by 70% of responders and the majority had adopted SBRT in 2010 or later. Quick turn around time, high dose delivery and competitive market forces were major factors to adopt SBRT. Lung was the most common site practiced followed by prostate, spine, and liver. All SBRT users were keen to increase SBRT in practice and the majority of non-responders were planning to adapt SBRT in the recent future. Almost half of SBRT users were willing to share data and expertise for training others. Lack of infrastructure was the prime reason for not practicing SBRT. ROP's perceived physics, radiobiology as the biggest challenge in SBRT. International collaboration may be helpful. Use of SBRT is expected to increase in India. Limited experience with lack of infrastructure in public funded centers is a major limitation. Unmet need of infrastructure, training and guidelines is enormous and formulation of Indian SBRT consortium will help reforming at all levels.

A Survey of Stereotactic Body Radiotherapy in Korea.

PurposeThe purpose of this study is to investigate the current status of stereotactic body radiotherapy (SBRT) in Korea. A nationwide survey was conducted by the Korean Stereotactic Radiosurgery Group of the Korean Society for Radiation Oncology (KROG 13-13).Materials and MethodsSBRT was defined as radiotherapy with delivery of a high dose of radiation to an extracranial lesion in ≤ 4 fractions. A 16-questionnaire survey was sent by e-mail to the chief of radiation oncology at 85 institutions in June 2013.ResultsAll institutions (100%) responded to this survey. Of these, 38 institutions (45%) have used SBRT and 47 institutions (55%) have not used SBRT. Regarding the treatment site, the lung (92%) and liver (76%) were the two most common sites. The most common schedules were 60 Gy/4 fractions for non-small cell lung cancer, 48 Gy/4 fractions for lung metastases, 60 Gy/3 fractions for hepatocellular carcinoma, and 45 Gy/3 fractions or 40 Gy/4 fractions for liver metastases. Four-dimensional computed tomography (CT) was the most common method for planning CT (74%). During planning CT, the most common method of immobilization was the use of an alpha cradle/vacuum-lock (42%).ConclusionBased on this survey, conduct of further prospective studies will be needed in order to determine the appropriate prescribed doses and to standardize the practice of SBRT.

Definition of stereotactic body radiotherapy: principles and practice for the treatment of stage I non-small cell lung cancer.

This report from the Stereotactic Radiotherapy Working Group of the German Society of Radiation Oncology (Deutschen Gesellschaft für Radioonkologie, DEGRO) provides a definition of stereotactic body radiotherapy (SBRT) that agrees with that of other international societies. SBRT is defined as a method of external beam radiotherapy (EBRT) that accurately delivers a high irradiation dose to an extracranial target in one or few treatment fractions. Detailed recommendations concerning the principles and practice of SBRT for early stage non-small cell lung cancer (NSCLC) are given. These cover the entire treatment process; from patient selection, staging, treatment planning and delivery to follow-up. SBRT was identified as the method of choice when compared to best supportive care (BSC), conventionally fractionated radiotherapy and radiofrequency ablation. Based on current evidence, SBRT appears to be on a par with sublobar resection and is an effective treatment option in operable patients who refuse lobectomy.

Safety and Efficacy of Stereotactic Body Radiotherapy for Stage I Non–Small-Cell Lung Cancer in Routine Clinical Practice: A Patterns-of-Care and Outcome Analysis

To evaluate safety and efficacy of stereotactic body radiotherapy (SBRT) for stage I non-small-cell lung cancer (NSCLC) in a patterns-of-care and patterns-of-outcome analysis. The working group "Extracranial Stereotactic Radiotherapy" of the German Society for Radiation Oncology performed a retrospective multicenter analysis of practice and outcome after SBRT for stage I NSCLC. Sixteen German and Austrian centers with experience in pulmonary SBRT were asked to participate. Data of 582 patients treated at 13 institutions between 1998 and 2011 were collected; all institutions, except one, were academic hospitals. A time trend to more advanced radiotherapy technologies and escalated irradiation doses was observed, but patient characteristics (age, performance status, pulmonary function) remained stable over time. Interinstitutional variability was substantial in all treatment characteristics but not in patient characteristics. After an average follow-up of 21 months, 3-year freedom from local progression (FFLP) and overall survival (OS) were 79.6% and 47.1%, respectively. The biological effective dose was the most significant factor influencing FFLP and OS: after more than 106 Gy biological effective dose as planning target volume encompassing dose (N = 164), 3-year FFLP and OS were 92.5% and 62.2%, respectively. No evidence of a learning curve or improvement of results with larger SBRT experience and implementation of new radiotherapy technologies was observed. SBRT for stage I NSCLC was safe and effective in this multi-institutional, academic environment, despite considerable interinstitutional variability and time trends in SBRT practice. Radiotherapy dose was identified as a major treatment factor influencing local tumor control and OS.