Extracranial Stereotactic Radiotherapy Research Articles

PO-1499 Extracranial stereotactic radiotherapy in low and favourable intermediate risk prostate cancer

PO-1499 Extracranial stereotactic radiotherapy in low and favourable intermediate risk prostate cancer

P2.01-02 Delivery of Concurrent Extracranial Stereotactic Body Radiotherapy with Osimertinib for Oligoprogressive EGFR Mutated Stage IV NSCLC

Osimertinib is a third generation Tyrosine Kinase Inhibitor (TKI) and is considered first line therapy for patients with metastatic Epidermal Growth Factor Receptor (EGFR) NSCLC with exon 19 deletion or exon 21 L858R. Osimertinib has demonstrated improved progression free survival (PFS) and overall survival (OS) compared to first generation TKI’s. However, during the course of their disease many patients develop oligoprogressive disease (OPD): <=3 metastatic lesions with otherwise controlled systemic disease.

Improving Education in Radiation Oncology in Poland

Background A national, anonymous survey evaluating the quality of radiation oncology training in Poland was conducted by young members of Polish Society of Radiation Oncology (yPTRO) in 2018 and more than 70% radiation oncology (RO) trainees participated. We noted that courses included into the specialty program were not sufficient for up to 80% of participants. Thus, we identified several aspects of the training requiring modifications. To address those issues, we introduced a new set of on-line lectures prepared by yPTRO members. Methods Based on the survey and the questionnaire on social media, we started a series of on-line educational lectures hosted on video conference software. Topics were chosen by RO trainees. Sessions were recorded and are publicly available. Pre- and post-surveys of participants which evaluated the quality of the sessions were conducted in half of the cases. Sessions were advertised via social media on dedicated RO groups. Results Four lectures were held from April to October 2021. We covered the following topics of: consolidation immunotherapy in stage III NSCLC, introduction to biostatistics, radiotherapy in (oligo)metastatic prostate cancer and emergencies in RO. As of now, the lectures had almost 600 views. One woman and three men from four different institutions presented the lectures which lasted from 45 to 200 minutes. Based on the evaluation, the consolidation immunotherapy was considered the most useful. However, the participants reported that more case-based discussion is needed. Biostatistical workshops got 4.8/5.0 points and besides too long time of the lecture (the one which took more than 3 hours) were received as very well prepared. Similar to the immunotherapy lecture, more practical and case based aspects were recognized as necessary in the future lectures. The optimum frequency of the lectures declared by the majority of responders was once a month. Further lectures will cover the topics of brain tumours and various aspects of cranial and extracranial stereotactic radiotherapy. Discussion We believe that virtual education on an online platform is a practical and feasible way of collaboration on national level. We expect this effort will result in an improved confidence of RO trainees and will broaden the knowledge of the participants. A national, anonymous survey evaluating the quality of radiation oncology training in Poland was conducted by young members of Polish Society of Radiation Oncology (yPTRO) in 2018 and more than 70% radiation oncology (RO) trainees participated. We noted that courses included into the specialty program were not sufficient for up to 80% of participants. Thus, we identified several aspects of the training requiring modifications. To address those issues, we introduced a new set of on-line lectures prepared by yPTRO members. Based on the survey and the questionnaire on social media, we started a series of on-line educational lectures hosted on video conference software. Topics were chosen by RO trainees. Sessions were recorded and are publicly available. Pre- and post-surveys of participants which evaluated the quality of the sessions were conducted in half of the cases. Sessions were advertised via social media on dedicated RO groups. Four lectures were held from April to October 2021. We covered the following topics of: consolidation immunotherapy in stage III NSCLC, introduction to biostatistics, radiotherapy in (oligo)metastatic prostate cancer and emergencies in RO. As of now, the lectures had almost 600 views. One woman and three men from four different institutions presented the lectures which lasted from 45 to 200 minutes. Based on the evaluation, the consolidation immunotherapy was considered the most useful. However, the participants reported that more case-based discussion is needed. Biostatistical workshops got 4.8/5.0 points and besides too long time of the lecture (the one which took more than 3 hours) were received as very well prepared. Similar to the immunotherapy lecture, more practical and case based aspects were recognized as necessary in the future lectures. The optimum frequency of the lectures declared by the majority of responders was once a month. Further lectures will cover the topics of brain tumours and various aspects of cranial and extracranial stereotactic radiotherapy. We believe that virtual education on an online platform is a practical and feasible way of collaboration on national level. We expect this effort will result in an improved confidence of RO trainees and will broaden the knowledge of the participants.

A review of surface guidance in extracranial stereotactic body radiotherapy (SBRT/SABR) for set-up and intra-fraction motion management

IntroductionSurface guidance (SG) radiotherapy (RT) is now used by many radiotherapy departments globally and has expanded in popularity over the last number of years. A number of commercial systems are available. SG has routinely been used and is well established for cranial stereotactic radiosurgery (SRS) patient set ups and intra-fraction motion monitoring.However, data is limited in relation to its clinical use for extracranial stereotactic body radiotherapy (SBRT), particularly for targets which are impacted by respiratory motion such as the lung and liver.Objective & Information SourceA review of available literature was carried out on 24th October 2021 to assess the clinical feasibility and use of SG in SBRT via PubMed.MethodsEligibility CriteriaThe search criteria involved identifying articles where SG is used in extracranial SBRT.Risk of BiasTo eliminate the risk of bias, any particular commercial system was not the focus of the review and not included in the search criteria. Numerous clinical terms for similar things were used to reduce the risk of missing papers e.g. SBRT and SABR.Search CriteriaThe PRISMA checklist was used. Searching for “surface guidance and radiotherapy” yielded 3271 results, where as “SGRT” alone returned 72 results, when the search term was narrowed down using different iterations of SG and SBRT, only 6 results were available. Of these, 4 had reviewed clinical data in relation to SG and SBRT for patient set up and intra-fraction motion monitoring.ResultsThe 4 studies indicate positive results for using SG with sufficient image guidance (IG) for both patient set up and intra-fraction monitoring during SBRT. This was observed both in free breathing and in patients with respiratory motion management being employed such as deep inspiration breath-hold (DIBH) techniques. All used multiple IGRT solutions to verify localisation pre-treatment in conjunction with SG.LimitationsThe number of studies available which report using SG in SBRT is extremely limited. All centres had also installed SG systems therefore this could result in an unconditional bias in using the system positively.ConclusionSG can be used for SBRT set-ups and intra-fraction motion monitoring once sufficient IG is used to verify target localisation for treatment.

Outcomes of extra-cranial stereotactic body radiotherapy for metastatic breast cancer: Treatment indication matters

Background and purposeTo summarize the clinical outcomes of stereotactic body radiotherapy (SBRT) for metastatic breast cancer (mBC) from a large institution. Materials and methodsPatients with mBC who received extra-cranial SBRT to metastatic lesions from 2011 to 2017 were identified. Treatment indications were: oligometastases, oligoprogression, and local control of dominant tumor (CDT). Endpoints included overall survival (OS), progression-free survival (PFS), local control (LC) and cumulative incidence of starting/changing chemo or hormonal therapy (SCT). Univariate and multivariate analyses were used to identify predictive factors. ResultsWe analyzed 120 patients (193 treated metastatic lesions) with a median follow up of 15.25 months. 1-and 2-year LC rates were 89% and 86.6%, respectively. 1-and 2-year OS rates were 83.5% and 70%, respectively, with treatment indication and molecular subtype being the predictive factors on MVA. 1-year OS was 91.0%, 78.5% and 63.9% for oligometastases, oligoprogression and CDT, respectively (p = 0.003). The worst OS was seen in basal subtype with 1-and 2-year OS rates of 59.2% and 39.5% (p = 0.01). Treatment indication was found to be predictive for PFS and lower rates of SCT on MVA. 1-and 2-year PFS rates were 45% and 32%, respectively. The 1-year PFS for oligometastases, oligoprogression, and CDT was 66%, 19.6%, and 14.3%, respectively (p < 0.001). The cumulative incidence of SCT at 1-year was 12% for oligometastases, 39.7% for oligoprogression and 53.3% for CDT (p < 0.001). ConclusionPatients treated for oligometastases have better OS and PFS than those treated for oligoprogression or CDT. SBRT may delay SCT in mBC patients, particularly those with oligometastases. SBRT provided an excellent LC in mBC patients.

Recommended procedures and responsibilities for radiosurgery (SRS) and extracranial stereotactic body radiotherapy (SBRT): report of the SEOR in collaboration with the SEFM.

Today, patient management generally requires a multidisciplinary approach. However, due to the growing knowledge base and increasing complexity of Medicine, clinical practice has become even more specialised. Radiation oncology is not immune to this trend towards subspecialisation, which is particularly evident in ablative radiotherapy techniques that require high dose fractions, such as stereotactic radiosurgery (SRS), and stereotactic body radiotherapy (SBRT). The aim of the present report is to establish the position of the Spanish Society of Radiation Oncology (SEOR), in collaboration with the Spanish Society of Medical Physics (SEFM), with regard to the roles and responsibilities of healthcare professionals involved in performing SRS and SBRT. The need for this white paper is motivated due to the recent changes in Spanish Legislation (Royal Decree [RD] 601/2019, October 18, 2019) governing the use and optimization of radiotherapy and radiological protection for medical exposure to ionizing radiation (article 11, points 4 and 5) [1 ], which states: "In radiotherapy treatment units, the specialist in Radiation Oncology will be responsible for determining the correct treatment indication, selecting target volumes, determining the clinical radiation parameters for each volume, directing and supervising treatment, preparing the final clinical report, reporting treatment outcomes, and monitoring the patient's clinical course." Consequently, the SEOR and SEFM have jointly prepared the present document to establish the roles and responsibilities for the specialists-radiation oncologists (RO), medical physicists (MP), and related staff -involved in treatments with ionizing radiation. We believe that it is important to clearly establish the responsibilities of each professional group and to clearly establish the professional competencies at each stage of the radiotherapy process.

Stereotactic Body Radiotherapy for Lymph Node Oligometastases: Real-World Evidence From 90 Consecutive Patients.

AimsTo evaluate the efficacy and toxicity of extracranial stereotactic body radiotherapy (SBRT) in the treatment of oligometastatic lymph node involvement in the mediastinum, retroperitoneum, or pelvis, in a consecutive group of patients from real clinical practice outside clinical trials.MethodsA retrospective analysis of 90 patients with a maximum of four oligometastases and various primary tumors (the most common being colorectal cancers). The endpoints were local control of treated metastases (LC), freedom from widespread dissemination (FFWD), progression-free survival (PFS), overall survival (OS), and freedom from systemic treatment (FFST). Acute and delayed toxicities were also evaluated.ResultsThe median follow-up after SBRT was 34.9 months. The LC rate at three and five years was 68.4 and 56.3%, respectively. The observed median FFWD was 14.6 months, with a five-year FFWD rate of 33.7%. The median PFS was 9.4 months; the three-year PFS rate was 19.8%. The median FFST was 14.0 months; the five-year FFST rate was 23.5%. The OS rate at three and five years was 61.8 and 39.3%, respectively. Median OS was 53.1 months. The initial dissemination significantly shortened the time to relapse, death, or activation of systemic treatment—LC (HR 4.8, p < 0.001), FFWD (HR 2.8, p = 0.001), PFS (HR 2.1, p = 0.011), FFST (HR 2.4, p = 0.005), OS (HR 2.2, p = 0.034). Patients classified as having radioresistant tumors noticed significantly higher risk in terms of LC (HR 13.8, p = 0.010), FFWD (HR 3.1, p = 0.006), PFS (HR 3.5, p < 0.001), FFST (HR 3.2, p = 0.003). The multivariable analysis detected statistically significantly worse survival outcomes for initially disseminated patients as well as separately in groups divided according to radiosensitivity. No grade III or IV toxicity was reported.ConclusionOur study shows that targeted SBRT is a very effective and low toxic treatment for oligometastatic lymph node involvement. It can delay the indication of cytotoxic chemotherapy and thus improve and maintain patient quality of life. The aim of further studies should focus on identifying patients who benefit most from SBRT, as well as the correct timing and dosage of SBRT in treatment strategy.

Extracranial Stereotactic Body Radiotherapy in Oligometastatic or Oligoprogressive Breast Cancer.

Purpose/Objective: Oligometastatic disease (OMD) and oligoprogressive disease (OPD) describe tumor states with a limited metastasization. In contrast to other disease states, treatment of OMD or OPD has not yet become common for breast cancer. We sought to understand the outcomes and toxicities of this treatment paradigm.Material/Methods: We retrospectively analyzed female breast cancer patients with OMD (≤3 metastases) or OPD (1 progressive lesion) who received stereotactic body radiotherapy (SBRT) for their respective extracranial metastatic lesions between 01/2002 and 07/2019. Survival analysis was performed using the Kaplan-Meier method with log-rank test being used for evaluation of significance. Cox regression was used to detect prognostic outcome factors. Toxicity was evaluated using the Common Terminology Criteria for Adverse Events (CTCAE v. 5.0).Results: Forty-six patients (70% OMD; 30% OPD) with 58 lesions met criteria for inclusion. The majority of treatments (34 out of 58; 58.6%) were delivered from 2017 to 2018. Treatment sites were bone, liver, lung [n = 19 (33%) for each site], and adrenal gland [n = 1 (1%)]. Median biologically effective dose (BED at α/β = 10) was 81.6 Gy (range: 45–112.5 Gy) and median planning target volume was 36.60 mL (range: 3.76–311.00 mL). At 2 years, local control (LC) was 89%, distant control (DC) was 44%, progression free survival (PFS) was 17% and overall survival (OS) was 62%. Multivariate analysis identified the diagnosis of a solitary metastasis as an independent prognostic factor for superior DC (HR = 0.186, CI [0.055; 0.626], p = 0.007) and PFS (HR = 0.363, CI [0.152; 0.863], p = 0.022). OS was independently inferior for patients treated at a higher age (HR = 5.788, CI [1.077; 31.119] p = 0.041). Nine (15.5%) grade I° and one (1.7%) grade II° toxicities were recorded, with no grade III° or higher toxicities.Conclusion: Extracranial SBRT in breast cancer patients with OMD or OPD was well-tolerated with excellent LC. SBRT should especially be offered to younger OMD and OPD breast cancer patients with only one metastasis. The increase in utilization since 2017 points toward a growing acceptance of SBRT for OMD and OPD in breast cancer.

Stereotactic Body Radiotherapy of Lymph Node Oligometastases

The aim of this retrospective study is to evaluate the efficacy and toxicity of extracranial stereotactic radiotherapy for the treatment of oligometastatic lymph node involvement in the mediastinum, retroperitoneum, and pelvis in a consecutive group of patients from real clinical practice. Of a total of 50 patients treated between 2011 and 2017, 29 were men and 21 were women, and the mean age was 62 years (median 66 years, range 25-81 years). Patients were most often irradiated in five fractions; the dose was selected according to dose-volume histograms of organs-at-risk in proximity to the planning target volume. The primary objectives were local control (LC), progression-free survival (PFS), time to multiple dissemination not allowing the use of local treatment methods (freedom from widepread dissemination - FFWD), and overall survival (OS). Acute and delayed toxicity were evaluated as well. The median dose equivalent at &#945;/&#946; = 10 (BED10) was 54 Gy (range 48-80 Gy). The median follow-up period was 40.4 months. LC after irradiation was 90% in 1 year and 75% in 3 years. Median time to local progression was not achieved. Patients irradiated with a high dose had significantly better LC than patients irradiated with a low dose; the cut-off was the median of the applied dose (ie BED10 = 54 Gy). Pathological node localization had no significant effect on LC. The median PFS was 8.2 months (95% CI 7.4-11.6 months). PFS in 1 year was 38.5% and 17% in 3 years. The median OS was 37.3 months (95% CI 23.2-51.4 months). One-year OS was 83% and 3-year OS was 51%. The median FFWD was 13.6 months (range 8.7-18.5 months). The one-year FFWD was 55% and the 3-year FFWD was 24%. None of these parameters (PFS, OS, FFWD) was dose or localization dependent. No grade III or IV toxicity was reported. Our study shows that targeted stereotactic radiotherapy is a very effective low toxic treatment for oligometastatic lymph node involvement. It can delay cytotoxic chemotherapy and thus improve/maintain the quality of life of patients. Approximately one fifth of patients treated with extracranial stereotactic radiotherapy for oligometastatic lymph node involvement survived without signs of disease for prolonged periods. Future studies should aim at identifying patients who would benefit most from this treatment, adjusting the timing of extracranial stereotactic radiotherapy depending on the treatment strategy, and optimizing the dose prescription. This work was supported by grant of the Ministry of Health of the Czech Republic AZV 19-00354 and by grant of the Ministry of Health of the Czech Republic - Conceptual development of a research organization (MMCI 00209805). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.

Treatment Outcome of metastatic lesions from renal cell carcinoma underGoing Extra-cranial stereotactic body radioTHERapy: The together retrospective study

Objectivesstereotactic body radiation therapy (SBRT) use has increased overtime for the management of metastatic renal cell carcinoma (mRCC) patients, with a likely good control of irradiated lesions. We planned a retrospective multicenter Italian study, with the aim of investigating the outcome of treatment with SBRT for non-brain secondary lesions in mRCC patients. Methodsall consecutive metastatic non-brain lesions from mRCC that underwent SBRT at nine Italian institutions from January 2015 to June 2017 were considered. The primary endpoint of the study was the lesion-PFS, calculated from SBRT initiation to the local progression of the irradiated lesion. Results57 extracranial metastatic lesions from 48 patients with primary mRCC were treated with SBRT. At the median follow-up of 26.4 months, the median lesion-PFS was not reached (43 censored); 72.4% of lesions were progression-free at 40 months, with significantly better lesion-PFS for small metastatic lesions (<14 mm). SBRT was safe and the 1-year local disease control was 87.7%. After SBRT, 18 patients (37.5%) permanently interrupted systemic therapy. Conclusionsconsistently with the previous literature, our findings support the use of SBRT in selected mRCC patients.

Outcomes of extra-cranial stereotactic body radiotherapy for metastatic colorectal cancer: Dose and site of metastases matter

Background and purposeTo review the clinical outcomes following the use of stereotactic body radiotherapy (SBRT) in patients with metastatic colorectal cancer (mCRC) from a large academic institution. Materials and methodsPatients with mCRC treated with extracranial SBRT between 2008 and 2016 were identified from an institutional database. Treatment indications were oligometastases, oligoprogression, and local control of dominant tumors. Endpoints included local progression (LP), overall survival (OS), progression-free survival (PFS), and cumulative incidence of starting or changing systemic therapy (SCST). Univariate and multivariable analyses (MVA) were performed to identify predictive factors. ResultsOne hundred and sixty-five patients (262 lesions treated) were included. The 2-year cumulative incidence of LP was 23.8%. Lower SBRT doses and tumor location in the liver were significant predictors of LP on MVA. Median OS was 49.3 months, 19.3 months, and 9.0 months for oligometastases, oligoprogression, and local control of dominant tumors, respectively. Primary tumor not in situ, smaller tumors, fewer lines of previous systemic therapy, lower CEA, and oligometastases treatment indications were significant predictors of higher OS on MVA. For the entire cohort, median PFS was 9.9 months, while oligometastatic patients had a median PFS of 12.4 months. 2-year cumulative incidence of SCST was 41.7%. ConclusionsSurvival outcomes are favorable after SBRT for mCRC patients. A significant proportion of patients did not have a change in systemic therapy after SBRT. Higher doses are required to obtain the best local control. Efforts should be made to better optimize SBRT delivery for liver metastases given their higher local failure rate.

Abstract P1-17-06: Outcomes of central nervous system radiotherapy for metastatic breast cancer: The Royal Marsden experience 2000 - 2016

Abstract Background: Breast cancer (BC) is one of the most common malignancies affecting women. Brain metastatses (BM) are frequently seen in BC, and can have devastating consequences with significant associated morbidity and mortality. Whole brain radiotherapy (WBRT) is commonly used to treat BM, with variable use of stereotactic radiotherapy (SRT). This study reports on the outcomes of BC patients with BM who received central nervous system (CNS) radiotherapy over a 17-year period at the Royal Marsden Hospital (RMH). Methods: We included all BC patients who had WBRT with or without SRT for intra-parenchymal BM secondary to BC at RMH between 2000 and 2016 inclusive. Instances of meningeal involvement were excluded from analysis. Data collected included age, histological subtype, tumor grade, stage at original BC presentation, receptor status, date of BM diagnosis, number of metastases, size of largest BM, Eastern Cooperative Oncology Group (ECOG) score, presence of extra-cranial metastases (ECM), neurosurgery (NS) and stereotactic radiotherapy (SRT) details, and date of last follow up or death. Univariate and multivariate analyses were performed to analyze the effect of each variable on overall survival (OS) from date of BM. Results: A total of 426 patients were included with a median age of 54 years at BM diagnosis and a median time to BM from BC diagnosis of 43 months. At diagnosis, 94% had invasive ductal carcinoma (IDC) and 70% had Grade 3 disease. Stage IV disease at original BC presentation was seen in 18% of patients. Estrogen receptor (ER+) was positive in 57% (n = 236), progesterone receptor (PR+) in 44% (n = 147), and HER2 (HER2+) in 44% (n = 166). Twenty-two percent (n = 89) were triple negative (TN). Median number of BM was 4 (range 1 – 205) and 20% (n = 72) of patients had only 1 BM. Average size of the largest lesion was 26 mm (range 1 – 75). The ECOG score was 0 – 1 in 61% of patients. Ten percent of patients (n = 44) underwent SRT and 10% (n = 43) underwent NS. Three hundred and eighty patients had died at the time of analysis. Median OS from date of BM was 6.4 months. On univariate analysis, age &amp;lt; 60 years at BC diagnosis (8.1 vs. 4.0 months, p = 0.0007) and BM diagnosis (8.0 vs. 5.6 months, p = 0.03), ECOG status 0-1 (9.6 vs. 4.0 months, p = &amp;lt;0.0001), ER+ (8.0 vs. 6.0 months, p = 0.0007), PR+ (7.6 vs. 6.9 months, p = 0.04), HER2+ (10.5 vs. 5.6 months, p &amp;lt; 0 .0001), SRT (20.3 vs. 5.9 months, p &amp;lt; 0.0001) and NS (20.3 vs. 6.2 months, p &amp;lt; 0.0001) significantly predicted for improved OS. Triple negative status predicted for worse survival (5.6 months vs. 8.1 months, p &amp;lt; 0.0001). On multivariate analysis, ECOG status, ER+, HER2+, treatment with SRT and NS were independent predictors for OS. Conclusions: This study confirms substantial heterogeneity of prognosis in patients with BM from BC, with significantly improved survival in patients selected for SRT or surgery. Further studies are required to optimize the role of CNS radiotherapy techniques such as SRT and hippocampal sparing WBRT in patients with a favorable prognosis. Citation Format: Kothari G, De Ieso PB, Mohammed K, Ross GM. Outcomes of central nervous system radiotherapy for metastatic breast cancer: The Royal Marsden experience 2000 - 2016 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-17-06.

54. Stereotactic plans quality assurance with Delta 4PT phantom

Introduction As treatment plans of intra and extracranial stereotactic radiotherapy do not benefit in vivo dosimetry, it is a common practice to perform a pretreatment quality control of the dose calculated by the treatment planning system (TPS). In the midst of the different solutions proposed in terms of detectors, we wanted to evaluate the performances of the Delta 4PT (Scandidos) phantom for the measurement of dynamic conformal arctherapy fields. We were then able to define evaluation criteria which proved to be suitable for the whole range of field dimensions in stereotactic radiotherapy (fields of 10 × 10 mm and more). Methods At the Jean PERRIN center, stereotactic radiotherapy treatment plans are mainly calculated with the iPlan TPS from Brainlab (v4.5). A dedicated module, “Phantom Mapping 4.5.4”, allows to calculate the plan on the Delta 4PT phantom CT image. The treatments were then delivered by a Novalis TrueBeam STX linear accelerator (Varian) for 6 MV photon beams in FFF (Flattening Filter Free) mode. The Delta 4PT used for the measurement is a cylindrical PMMA phantom containing 2 planes of orthogonal p-Si detectors. These very small volume detectors are spaced 5 mm apart on a surface of 6 × 6 cm in the center then every 10 mm on the perimeter. The Delta 4PT has been previously calibrated for energy 6 FFF to take into account the energy response. We also took advantage of the “High Resolution” option of the Delta 4PT phantom to double the longitudinal resolution (2.5 mm). Several sets of parameters were tested for the studied treatment plans. For the analysis, we choosed four parameters: the gamma score, the mean gamma, the number of detectors taken into account in the statistics and the median dose. A comparison with the results obtained by VARIAN’s Portal Dose Image Prediction (PDIP) solution was also carried out to indicate the limits of these two pretreatment control methods. Results Statistical and rational analyzes show that an optimal parameter set makes it possible to verify that the Delta 4PT can be used for all types of dynamic conformal arctherapy treatment plans. Initial results show that the absolute dose measured with The Delta 4PT is correct with an average median dose of −0.4% and a standard deviation of 0.75%. The gamma score (2%/2 mm) systematically passes the criteria of the 95% of points having a gamma of less than 1. Moreover, the results obtained for the PDIP are similar. Conclusions A threshold of 30% with a 2%/2 mm criteria on the local gamma seems to be a good compromise for all field sizes. The physical and dosimetric characteristics of the Delta 4PT phantom allow it to be integrated into a quality assurance plan, whether in classic VMAT or stereotactic radiotherapy.

Robot-assisted Extracranial Stereotactic Radiotherapy of Adrenal Metastases in Oligometastatic Non-small Cell Lung Cancer.

The aim of this study was to evaluate the efficacy and toxicity of stereotactic body radiation therapy (SBRT) in the treatment of patients with adrenal metastases in oligometastatic non-small-cell lung cancer (NSCLC). Between November 2012 and May 2015, fifteen patients with oligometastatic non-small cell lung cancer and adrenal metastases were treated with the Cyberknife® system. The primary endpoint was local control. The 1-year and 2-year local control rates were 60% and 46.6%, respectively. The differences in local control for patients with metachronous and synchronous metastases reached statistical significance (p=0.00028). Two-year overall survival of 91.2% for patients with metachronous metastases was also more favourable compared to patients with synchronous adrenal metastases with 42.8%. Extracranial stereotactic radiotherapy with the Cyberknife® is a safe and non-invasive technique that extends the therapeutic spectrum in the treatment of patients with adrenal metastases in oligometastatic NSCLC.

Large scale adoption of statistical process control (SPC) for volumetric modulated ARC therapy patient-specific quality assurance: A retrospective analysis on 1400 patients

Introduction Statistical Process Control (SPC) is a tool widely used in industrial engineering for monitoring, controlling and, ideally, improving a process through statistical analysis. This technique can be applied to quality assurance (QA) practice in radiotherapy in order to characterize the treatment process variability. Purpose To apply SPC strategy to our routine VMAT pre-treatment verification QA. Materials and methods In the last years, more than 1400 patients were treated with Elekta VMAT at our institution. Plans were re-grouped according to treatment technique and disease sites: (1) 611 high-modulated complex SIB treatments (head-neck, brain, gynecological, ano-rectal; (2) 348 prostate treatments and (3) 445 liver, lung and other metastasis treated with extracranial stereotactic radiotherapy (SBRT). Groups 1 and 2–3 plans were optimized with Oncentra Masterplan (dual-arc) and Ergo++ (single arc) TPS. A total of 4030 dose measurements were performed with the PTW Seven29 array/Octavius phantom, both on coronal and sagittal planes. Doses comparison were evaluated using 3%/3 mm γ -analysis. Two metrics were evaluated: (a) points-percentage with g -value less than one (g%) and (b) mean gamma (gmean). Clinical specifications were: g % >90% and g mean Results γ pass-rate values significantly depend on plan complexity. For g %, CL and LCL were 93.9% and 89.4%, 99.1% and 96.6%, and 99.3% and 97.6%, for group 1, 2 and 3 respectively. For gmean, CL and UCL were 0.416 and 0.585, 0.361 and 0.557, and 0.304 and 0.427, for groups 1, 2 and 3 respectively. In all cases, the control limits are well within the clinical specifications. The Cpl/Cpu capability indices for g % and g mean resulted equal to 0.61 and 1.06 in group 1; 2.59 and 1.12 in group 2; 3.77 and 2.10 in group 3, respectively. g % process for group 1 was not capable at 3%/3 mm, but with 5% – 3 mm specification for g%, CL and LCL resulted 98.3% and 96.2% and Cpl was 2.84. Conclusion SPC is useful to quantifiably demonstrate the QA process conformance to clinical specifications.

A.195 - The use of a redundant independent calculation software in the extra-cranial stereotactic small field radiotherapy as part of quality assurance program

THE USE OF A REDUNDANT INDEPENDENT CALCULATION SOFTWARE IN THE EXTRA-CRANIAL STEREOTACTIC SMALL FIELD RADIOTHERAPY AS PART OF QUALITY ASSURANCE PROGRAM G. Rossi *,a, A. Pentiricci a,b, F. Chionne b, M. Alessandro c. a AUSL Umbria 1 – Unita di Staff di Fisica Sanitaria, Citta di Castello, PG, Italy; b AUSL Umbria 1 – Unita di Staff di Fisica Sanitaria, Perugia, Italy; c AUSL Umbria 1 – S.C. di Radioterapia Oncologica, Citta di Castello, PG, Italy

Radiothérapie des cancers métastatiques ou oligométastatiques en dehors des irradiations à visée antalgique. État des lieux en 2010 avec focus sur l'Asco 2010

The role of radiation therapy in metastatic disease has evolved from palliative to potentially curative intent for selected oligometastases using highly conformal radiation techniques, including extracranial stereotactic body radiotherapy (SBRT) in the last decade. SBRT has a potential to use small numbers of large doses aiming at achieving high rates of local control while preserving the quality of life even in highly pretreated patients. A wide range of techniques, doses, and dose fractionation schedules can be found. However, the 2-year local control is around 80% for lung metastases with corresponding 2-year survival of 50%, and a 5% rate of grade III or higher radiation toxicities. The 2-year local control varies between 57 and 92% for liver metastases and radiation-induced liver disease is exceptional provided that 700cm3 of healthy liver are irradiated to less than 15 Gy in three fractions or more. Stereotactic radiation is also particularly interesting for spinal, and cranial metastases and reirradiations. Also, it has come into focus that associations of chemotherapy or targeted therapies and radiation may be used for optimized treatment of limited metastatic disease and that irradiation of the primary tumor may be recommended in the context of metastatic disease. It also appears that the definition of target volumes for palliative radiation therapy and scores to assess for life expectancy-based need for irradiation should be improved.

What does the general and abdominal surgeon need to know about radiotherapy? - aspects of radiotherapy in general and abdominal surgery

Radiooncological therapies are an integral part of the multimodal oncological treatment concepts in general and abdominal surgery. These include therapeutic approaches with a curative intention such as the neoadjuvant (pre-operative) radiotherapy of locoregionally advanced and/or N+ oesophageal and rectal cancer, definitive combined chemoradiotherapy of locally advanced, unresectable oesophageal cancer or oesophageal tumour lesions of the upper third, definitive radiotherapy of anal cancer (sphincter sparing) and pre- or post-operative radiotherapy of soft tissue sarcoma on the one hand. A yT0 stage achieved as characteristic of a curative effect by radiation in oesophageal and rectal cancer (omitting subsequent surgical intervention, naturally under clinical and imaging-based controls within short-term follow-up intervals) can be considered as a very interesting set-up with regard to its reasonable integration in daily clinical practice, which needs to be further and critically discussed. By integrating radiotherapy in interdisciplinary therapy concepts, improved tumour control and survival rates with clinically acceptable toxicity can be achieved. On the other hand, non-invasive, locally ablative radiooncological therapies such as extracranial stereotactic body radiotherapy constitute an effective and feasible treatment method for liver metastases in oligometastatic colorectal cancer or other tumour entities according to the decisions by the institutional tumour board, offering high local tumour control rates which can be part of multistep, multimodal procedures with curative intention. This review aims at providing an overview for the general and abdominal surgeon, outlining relevant radiooncological treatment aspects in the multimodal cancer therapy with a focus on the treatment of rectal, oesophageal and anal cancer as well as soft tissue sarcoma and hepatic metastases in oligometastatic colorectal cancer.

Stereotactic radiotherapy for spinal meningiomas and neurinomas

Over the past decades, stereotactic conformal radiotherapy of intracranial meningiomas and schwannomas has been recognized as an effective and safe procedure. Due to the wide use of the CyberKnife system and the procedure of extracranial stereotactic radiotherapy and radiosurgery, the positive experience can be used to treat spinal tumors. This study assessed the effectiveness of stereotactic radiaotherapy of spinal meningiomas and neurinomas using the CyberKnife system. 46 patients (34 females and 12 males) received treatment between November 2009 and December 2013 (65 tumor nodules). The median age of patients receiving radiotherapy was 49 years (range: 20 to 82 years). Twenty neoplasms were subjected to surgical treatment. In 11 patients, formation of the recurrent tumor foci following treatment was observed along with the systemic disease, neurofibromatosis. Six patients had multiple meningiomas. The median total dose of radiation therapy of neurinomas was 13.6 Gy (12.1-14.1 Gy) per fraction; up to 18.2 Gy (16.0-21.1 Gy) per three fractions; and up to 25.6 Gy (24.8-27.6 Gy) per five fractions. Higher doses were used for meningiomas: 15.9 Gy (14.1-16.2 Gy) per fraction; 20.9 Gy (19.5-21.1 Gy) per three fractions; and 27.5 Gy (25.0-29.9 Gy) per five fractions. The load to 0.15 cm3 of the spinal cord was no higher than the maximum permissible load of 12 Gy per fraction. The mean catamnestic follow-up was 18.1 (4-52) months: 21,1 (4-52) months for neurinomas and 18 (4-31) months for meningiomas. We have not observed complete tumor elimination (i.e., complete response to radiation therapy) in our series. Partial response was observed in 9 (13.8%) cases; stabilization was achieved in 54 (83.1%) cases; and tumor continued to grow in 2 (3.1%) cases. The patients' status was evaluated using the Frankel, the Karnofsky, and the VAS scales. Our findings clearly demonstrate the short-term benefits of using CyberKnife radiotherapy for benign spinal cord tumors. The catamnestic follow-up needs to be extended to elaborate recommendations for radiation. The progress in this therapy type will considerably improve the quality of medical care provided to this cohort of patients.

Stereotactic Body Radiotherapy

Extracranial stereotactic body radiotherapy (SBRT) has been developed and refined over the last 25 years as a means to precisely deliver ablative doses of hypofractionated radiotherapy to small targets located outside of the cranial vault. SBRT has armed the radiation oncologist with a therapeutic approach that allows for intensification of both dose delivered and fractionation regimen employed. As a consequence, tumor control rates have improved to levels that previously have been associated only with surgical resection. Several prospective phase I and II studies have evaluated the use of SBRT for non-small cell lung cancer (NSCLC), liver tumors, and spinal metastases. This article will give an overview of SBRT and evidence for its use in the most common sites of disease for which it is employed today.