Stereotactic Ablative Body Radiotherapy Research Articles

Stereotactic Radiotherapy for Oligometastasis.

Oligometastatic disease is defined as “a condition with a few metastases arising from tumors that have not acquired a potential for widespread metastases.” Its behavior suggests a transitional malignant state somewhere between localized and metastatic cancer. Treatment of oligometastatic disease is expected to achieve long-term local control and to improve survival. Historically, patients with oligometastases have often undergone surgical resection since it was anecdotally believed that surgical resection could result in progression-free or overall survival benefits. To date, no prospective randomized trials have demonstrated surgery-related survival benefits. Short courses of highly focused, extremely high-dose radiotherapies (e.g., stereotactic radiosurgery and stereotactic ablative body radiotherapy (SABR)) have frequently been used as alternatives to surgery for treatment of oligometastasis. A randomized study has demonstrated the overall survival benefits of stereotactic radiosurgery for solitary brain metastasis. Following the success of stereotactic radiosurgery, SABR has been widely accepted for treating extracranial metastases, considering its efficacy and minimum invasiveness. In this review, we discuss the history of and rationale for the local treatment of oligometastases and probe into the implementation of SABR for oligometastatic disease.

SABR in clinical trials: what quality assurance (QA) is required and how can it be done?

Stereotactic Ablative Body Radiotherapy (SABR) has become widely used radiotherapy treatment modality for many indications ranging from early stage disease to an oligometastatic setting. All this combines the use of virtually all technological advances that characterise modern radiotherapy from small conformal fields to intensity modulation and explicit accounting for motion. However, given its novelty, clinical evidence for SABR is still emerging and many clinical trails include SABR as the intervention to define (eg in dose or fractionation defining studies) or to test against other treatment modalities. In any case, physical quality assurance (QA) must be an essential aspect of the trial to ensure that SABR is delivered accurately and in a comparable fashion in radiotherapy centres participating in the trial. The present paper tries to explore the balance between the QA cost and benefit for trial conduct in terms of patient numbers and timely completion of the trial.

Evaluation of dose calculation algorithms using different density materials for in-field and out-of-field conditions

The accuracy of the dose calculation is vital in the stereotactic ablative body radiotherapy (SABR) technique to achieve clinically effective dose distribution for better tumor control. Multiple commercial radiotherapy treatment planning systems (TPS) were implemented with different algorithms, such as Acuros XB in Eclipse and Superposition in XiO. The aim of this study is to investigate five different dose calculation algorithms, namely, pencil beam convolution (PBC), Acuros XB, AAA implemented in an Eclipse system, collapsed cone convolution (CCC) algorithm implemented in Mobius3D and superposition algorithms implemented in the XiO system, and then validate the results against measurements using an Institute of Physical Sciences in Medicine (IPSM) phantom with different density materials for in-field and out-of- field conditions. The IPSM phantom was used to investigate the dose calculation algorithm performances in four different densities (water, lung, ribs, and dense bone) using different beam configurations, including small beam fields utilised in lung SABR. Five commercial algorithms implemented in two TPS (Eclipse and XiO) and one plan check(M3D) system were used for in-field and out-of-field measurement. In the in-field condition, the Acuros XB algorithm had lower mean differences than the measured dose by the IC ranging from -0.46 to 0.24for all the densities. In the out-of-field condition, the results of eclipse system: AAA, PBC and Acuros XB algorithms demonstrated underdose point's measurements by -40% for all densities except for AAA calculations in lung density (overdosed by 40%). The measured points of the superposition algorithms were overestimated to the actual dose less than 30% in water, lung and dense bone. At the same densities, the CCC algorithms showed relatively the lowest differences in percentage compared to the superposition algorithms. Our results showed that the Acuros XB and superposition algorithms are closer to the actual measured dose than AAA, PBC and CCC for majority of the field conditions for water-equivalent, lung, rib and dense bone densities. The CCC algorithm resulted in a better agreement with the measurement of the out-of-field points compared with the other algorithms.

Investigation of dosimetric impact of organ motion in static and dynamic conditions for three stereotactic ablative body radiotherapy techniques: 3D conformal radiotherapy, intensity modulated radiation therapy, and volumetric modulated arc therapy by using presage 3D dosimeters.

To investigate the use of PRESAGE 3D dosimeters to quantify the dosimetric variation between the static and dynamic conditions of three stereotactic ablative body radiotherapy techniques. An in-house custom-designed thorax dynamic phantom was designed to simulate the tumor motion in two directions (i.e., superior/inferior (Z-axis) and anterior/posterior (Y-axis)). The PRESAGE dosimeter was attached to the moving arm of the phantom and irradiated in two scenarios (static and dynamic) using three stereotactic ablative body radiotherapy (SABR) techniques: 3D conformal radiotherapy (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT). The highest differences in the mean volume measurements between the two conditions were noticed in IMRT (0.14 cm3) and 3D CRT (0.13 cm3). The mean volume measurements of the VMAT showed the lowest difference between the static and dynamic conditions of 0.10 cm3. The gamma analysis for 3%, 3-mm criterion showed passing rates of < 1 for 3D CRT, IMRT, and VMAT. This study quantify the dosimetric variations which are caused by the tumor motion in lung cases. In the SABR of the lung for QA purposes, this could help in identifying the prescription dose coverage due to tumor movement and correlate with the planned dose using 3D dosimeters like PRESAGE.

The Liver INSPECTR Trial: Towards improved understanding of liver function following radiotherapy

Liver stereotactic ablative body radiotherapy (SABR) is an emerging treatment option for primary liver cancer and liver metastases. Liver SABR can provide high rates of local control however tumour doses are limited by dose to surrounding organs at risk including liver and gastrointestinal structures. Dose limits to liver are based on anatomical liver, without understanding of underlying liver function. This report describes a prospective clinical trial which measures the spatial variance of liver function through Tc-99m Mebrofenin SPECT in the context of liver SABR.

Acute radiation induced CT changes after stereotactic ablative body radiotherapy for primary non-small cell lung cancer

Acute radiation induced CT changes after stereotactic ablative body radiotherapy for primary non-small cell lung cancer

Outcomes after stereotactic ablative body radiotherapy for stage 1 lung cancer

Outcomes after stereotactic ablative body radiotherapy for stage 1 lung cancer

Promising Clinical Outcome With Long Term Follow-Up After Body Gamma Knife Stereotactic Radiosurgery for Patients With Early Stage Non-small Cell Lung Cancer.

Introduction: Stereotactic ablative radiosurgery (SRS) or stereotactic ablative body radiotherapy (SABR) is the standard treatment for patients with inoperable early stage non-small cell lung cancer (NSCLC), the body gamma knife SRS (ɤ-SRS) is a special SABR technology developed in China. This study prospectively assessed the clinical outcome, toxicity and cost following body ɤ-SRS for early stage NSCLC.Methods: From 2007 to 2010, a total of 29 patients with early stage NSCLC were prospectively enrolled in this study. The prescription dose for Planning Target Volume (PTV), Clinical Target Volume (CTV), and Gross Target Volume (GTV) were 50, 60, and 70 gray (Gy) in 10 fractions. Isodose curves of 50, 60, and 70% covered at least 100% of PTV, 90% of CTV, and 80% of GTV, respectively. The body ɤ-SRS was delivered 5 days per week and completed in 2 weeks.Results: Median follow-up time was 62.0 (range 11.1-140.3) months. 1-, 3-, 5-year OS rates were 93.1%, 72.0%, 60.3%; PFS rates were 86.2, 64.2 and 48.8%; and LR, RR, and DM rates were 10.9%, 21.4%, 29.0%. The median cost of the body ɤ-SRS during treatment was 4,838 (range 4,615–4,923) dollars and the median cost through 5 years was 36,960 (range 9920-56,824) dollars.Conclusion: With existing clinical data, the body ɤ-SRS is an effective treatment option for patients with medically inoperable early stage NSCLC or patients who do not prefer operation, as they may benefit from the minimized toxicity. Due to excellent cost effectiveness, the availability of the body ɤ-SRS will expand, especially in developing nations, and underdeveloped countries.

Beam selection for stereotactic ablative radiotherapy using Cyberknife with multileaf collimation

The Cyberknife system (Accuray Inc., Sunnyvale, CA) enables radiotherapy using stereotactic ablative body radiotherapy (SABR) with a large number of non-coplanar beam orientations. Recently, a multileaf collimator has also been available to allow flexibility in field shaping. This work aims to evaluate the quality of treatment plans obtainable with the multileaf collimator. Specifically, the aim is to find a subset of beam orientations from a predetermined set of candidate directions, such that the treatment quality is maintained but the treatment time is reduced. An evolutionary algorithm is used to successively refine a randomly selected starting set of beam orientations. By using an efficient computational framework, clinically useful solutions can be found in several hours. It is found that 15 beam orientations are able to provide treatment quality which approaches that of the candidate beam set of 110 beam orientations, but with approximately half of the estimated treatment time. Choice of an efficient subset of beam orientations offers the possibility to improve the patient experience and maximise the number of patients treated.

Clinical evidence for dose tolerance of the central nervous system in hypofractionated radiotherapy

Stereotactic radiosurgery (SRS), stereotactic body radiotherapy (SBRT), and stereotactic ablative body radiotherapy (SABR) are commonly used in the treatment of central nervous system (CNS) disease. This study has refined the radiation toxicity estimates for some normal tissues of the CNS based on review and analysis of the clinical evidence for single fraction radiosurgery, hypofractionated SBRT, and conventionally fractionated radiation therapy. Published guidelines and protocols are reviewed. In the past, many normal tissue tolerances were compiled based on the experience of the investigators and publications in the literature. Some tolerances were determined by modeling or calculation using the existing biological formulas, in particular the linear quadratic (LQ) model. In the present study, the estimate of risk for each dose tolerance limit in some CNS tissues is provided exclusively with normal tissue complication probability (NTCP). The clinical outcomes are compared to understand the difference in biological effect between radiosurgery and radiotherapy. Normal tissue dose tolerances and the corresponding complication rates are provided for brainstem, optic nerves, cochlea, and spinal cord, including single fraction SRS, five-fraction SBRT, and conventional radiation therapy. Calculation of biologically effective dose (BED) or single fraction equivalent dose (SFED) alone using the LQ model conveys no consensus on the biological effect across different fractionations. Comparison of conventional radiation therapy to brain and spinal cord with single fraction equivalent dose leads to even conflicting clinical outcomes. Effective differences between single fraction SRS and conventional radiotherapy need to be better understood. The existing biological model might not be valid to predict the radiosurgical outcomes based on conventionally fractionated radiotherapy. However, application of the statistical dose response models of clinical SRS and SBRT outcomes data to selected current dose tolerance guidelines into simple tables can be a clinically useful resource.

Are All Colorectal Oligometastases Equal?

Stereotactic ablative body radiotherapy (SBRT) is offered to patients who have oligometastatic (OM) disease and are not suitable for surgical treatments. OM Colorectal (CRC) cancer has been identified as potentially having worse outcomes compared to other histology types. We hypothesize that tumor biology impacts outcome in OM CRC. A single institution of prospectively CRC patients treated with SBRT. Patients had <3 mets, in <2 organs on multimodality imaging and exhausted local treatments options. The PS 0-1 SBRT was delivered in 3-8 fractions depending on location. The α/β = 10 was used to estimate biological dose. Location of primary and KRAS status was recorded. Progression was defined by imaging criteria as local (within field), locoregional (same organ but outside RT field) or distant. Univariate analysis was performed with log rank tests of Kaplan-Meier curves and cox proportional hazard models. Significant variables on univariate testing were entered into a multivariate cox proportional hazard model. Between 05/2013 and 11/2017, 53 CRC metastases cases were treated and 40 patients had adequate data. Eighteen (45%) synchronous, 32 pts had ≥1 line of chemo. The median age was 68.5 years (range 36-89). Twenty-four patients were male. Primary site of disease was rectum in 18 (45%), left colon in 15 (37.5%) and right colon in 6 (15%). OM sites treated: 16 liver, 15 nodes, 6 lung, and 3 bone. Median BED10 was 100 Gy (range 48 – 151.2). Median follow up was 14 months (range 2 - 43). In-field local control at 1 year was 83.5% (95% C.I 69.4 – 100). Median PFS for the cohort was 9 months (95% C.I 5.8 – 15.2). The median PFS for the liver, lung and node metastases were 5, 13, and 19 months respectively. There was a significant difference in PFS based on metastasis location, with lymph node disease being associated with improved PFS (HR 0.25, 95% C.I 0.09 – 0.69, p = 0.007; overall log rank, p = 0.02). KRAS status was available for 22 patients (55%), 13 wild type and 9 mutant, with the remainder untested. WT KRAS status was associated with improved PFS (HR 0.29, 95% C.I 0.09 – 0.9, p = 0.037). No significant difference in PFS was seen when comparing groups by primary site, colon side, age, gender, or whether presentation was with synchronous or metastatic disease. On MVA, metastasis location of lung and lymph node and KRAS WT or unknown status, remain statistically significant predictors of improved PFS. In this small cohort, lymph node metastases are associated with improved PFS compared to lung, bone or liver sites independent of KRAS status. KRAS WT is an independent predictor of progression free survival for treatment with SABR. These findings could be used to further refine the selection of CRC OM for treatment with SABR and incorporating systemic treatment. The excellent local control, regardless of KRAS subtype, suggests that OM PFS is driven by locoregional or widespread failure highlighting need for exploring biological differences.

Histology, Tumor Volume, and Radiation Dose Predict Outcomes in Non-Small Cell Lung Cancer Patients after Stereotactic Ablative Radiation Therapy

Histology, tumor volume, and radiation dose have been separately reported as possible predictors of recurrence in non-small cell lung cancer following stereotactic ablative body radiotherapy (SABR). However, it remains unclear if histology should be independently considered when choosing SABR dose prescriptions. The study population included 508 patients with 561 lesions treated between 2000 and 2016, of which 442 patients with 482 lesions had complete dosimetric information. The primary endpoint was in-field tumor control censored by either death or progression. Involved lobe control was also assessed. At a median follow-up of 6.7 years, 3-year in-field control, involved lobe control, overall survival, and progression-free survival were 88.1%, 80.0%, 49.4%, and 37.2%, respectively. Gross tumor volume (GTV, HR=1.01 per mL, p=0.0044) and histology (p=0.0225) were independently associated with involved lobe failure; GTV (HR=1.013, p=0.001) and radiation dose to the GTV (cutoff of 110Gy, biologically effective dose with α/β=10 [BED10], HR=2.380, p=0.0084) were independently associated with in-field failure. For squamous cell carcinomas, lower prescription doses were associated with worse in-field control independent of GTV (≤ vs. >110Gy BED10: HR=3.621, p=0.0147; 12Gyx4 or 10Gyx5 vs. 18Gy or 20Gyx3: HR=3.530, p=0.0447). For adenocarcinomas, there were no differences in in-field control observed using the above dose groupings (p=0.12 and p=0.31). GTV, dose to GTV, and histology are important factors contributing to involved lobe and in-field recurrence risk. A dose local control relationship was observed for squamous cell carcinomas treated with commonly used SABR dose prescriptions. In the absence of level I data to guide management, we posit that GTV and histology should be considered to personalize radiation dose for SABR. We suggest lower prescription doses (i.e., 12Gyx4 or 10Gx5) should be avoided for squamous cell carcinomas if there are no concerns about normal tissue toxicity.

Late Toxicity and Long-Term Local Control in Patients with Ultra-Central Lung Tumors Treated by IMRT Based -Stereotactic Ablative Body Radiation Therapy (SABR)

Late Toxicity and Long-Term Local Control in Patients with Ultra-Central Lung Tumors Treated by IMRT Based -Stereotactic Ablative Body Radiation Therapy (SABR)

Development of Best Practices of Peer Review in Lung Radiation Therapy

Given the increasing complexity in lung radiation therapy (RT), peer review (PR) is an important component in ensuring high quality and consistent RT plans. However there are inconsistencies in the extent, timing, and minimum requirements for PR across centres. We sought to develop guidelines of best practices for PR in curative lung RT through a Pan-Canadian expert consensus process. A modified Delphi process was conducted. A literature review was first carried out to define important elements for PR with respect to target delineation, organs-at-risk (OAR), and dosimetric plan quality, which was followed with an initial review by a dedicated steering committee. Candidate PR elements were then stratified by cases pertaining to treatment of locally-advanced (LA) disease with conventional RT, or stereotactic ablative body radiotherapy (SABR) for early-stage disease. A pan-Canadian, multidisciplinary Delphi panel was then assembled, and three Delphi rounds were undertaken (one pre-meeting survey, one face-to-face meeting, and one post-meeting ratification survey) to quantify participants’ rankings of the importance of each PR element, as well as the clarity of the wording for each. Finally, all endorsed elements were discussed for final wording by the steering committee. For LA cases, a total of six elements were considered as essential in the PR process. These included i) indications to treat with RT, ii) gross tumor volume (GTV), iii) clinical target volume (CTV), iv) internal target volume (ITV), v) dose/fractionation selection, and vi) normal lung dosimetry (ie V20, mean lung dose). Of these six elements, 90-100% of the panel in the final round endorsed these to be important to PR, and 80% felt that the PR should be done by a second radiation oncologist (RO). There were an additional three elements deemed optional for PR in these cases, including OAR contour review, PTV dosimetric coverage and maximum point dose, with review conditional dependent on the clinical scenario. In the cases of SABR, a total of six PR elements were deemed essential. These included i) indications to treat, ii) GTV, iii) CTV/ITV, iv) OAR contours, v) choice of dose/fractionation, and vi) review of composite plan for cases treated with previous RT. On the final round, 90-100% of panel members felt these elements to be important to PR, and unanimously agreed that PR should be done by a second RO. A further four elements were deemed optional based on the clinical scenario, including PTV dosimetric coverage, maximum point dose, OAR dosimetry, and best practices for daily image guidance. A suite of elements for lung radiation PR has been developed and endorsed with high consensus across a multidisciplinary group of national experts in lung RT. These elements should serve as a basis to help streamline and create consistency among PR practices across centres, and to help develop novel PR approaches going forward.

First-in-Human Clinical Experience with Real-Time Tumor Targeting Via MLC Tracking for Stereotactic Radiation Therapy of Lung Cancer

MLC tracking is an emerging technology to improve tumor targeting and reduce normal tissue irradiation during radiotherapy. The purpose of this work is to present the early clinical experience from the first-in-human trial of real-time tumor targeting via MLC tracking for stereotactic ablative body radiotherapy (SABR) of lung cancer. Twelve stage 1 lung cancer or lung metastases patients have been recruited into an ethics approved MLC tracking clinical trial (NCT02514512). Each patient has three electromagnetic beacons (Calypso) inserted into the lung surrounding the tumor. An MLC tracking SABR plan was generated with planning target volume (PTV) expanded 5mm from end-exhale tumor volume (GTV). For comparison a conventional motion-encompassing SABR plan was generated with PTV expanded 5mm from a 4DCT-derived internal target volume. Treatment was delivered using a standard linear accelerator using in-house developed software to continuously adapt the MLC motion based on the Calypso beacons’ movement. Tumor motion, treated volume, and reconstructed delivered dose were compared between MLC tracking and conventional motion-encompassing treatment planning. All 46 fractions from the twelve patients have been treated successfully with MLC tracking. The MLC tracking PTV for all patients has been smaller than with ITV based planning (range 12% to 41% reduction, or 2 to 18 cm3 with MLC tracking). Subsequent reductions in normal lung dose were observed. Mean lung dose reduced by up to 30% and on average by 19% (i.e., from 280 cGy to 225 cGy) with MLC tracking compared to ITV-based planning. Tumor motion was seen to vary in motion range during treatment, between fractions and from the planning 4DCT; significantly, larger motion was observed during treatment that exceeded standard PTV boundaries. Reconstruction of delivered treatments confirmed the accurate delivery of MLC tracking, with 100% prescribed dose delivered to the GTV for each of the 46 fractions. The first treatments with MLC tracking have been successfully performed in twelve lung cancer patients. Reductions in treated volumes were observed, which translated to reductions in delivered lung dose.

Radiotherapy patterns of care for stage I and II non-small cell lung cancer in Sydney, Australia.

Curative radiotherapy is guideline treatment for inoperable patients of good performance status with Stage I & II Non-Small Cell Lung Cancer (NSCLC). The aim of this study was to evaluate radiotherapy patterns of care in these patients, the reasons for palliative treatment and the proportion of patients suitable for curative stereotactic ablative body radiotherapy (SABR). Electronic oncology databases at three institutions were queried to retrieve data on patients with inoperable Stage I & II NSCLC seen in radiation oncology clinics between 1/1/2008 and 31/12/2014. Suitability for SABR was defined as peripheral tumours less than 5cm in size. Factors associated with curative treatment were determined using univariate and multivariate analyses. Three-hundred-and-twelve patients were identified of whom 178 (57%) received curative radiotherapy, 58 (19%) palliative radiotherapy and 76 (24%) no radiotherapy. The main reason for receiving palliative rather than curative treatment was COPD or poor pulmonary function (26%). Method of diagnosis (P=0.031), Simplified Comorbidity Score (P=0.003), ECOG performance status (P=0.016), FEV1% (P=0.040), treating institution (P<0.0001) and time period (P=0.016) were associated with curative radiotherapy on multivariate analysis. In patients with T1-2N0M0 NSCLC, 19 (31%) who did not receive treatment and 7 (21%) who underwent palliative radiotherapy were technically and clinically suitable for SABR. Only 57% of patients with Stage I-II NSCLC were treated with curative radiotherapy. Patient factors were the predominant reason for palliative treatment, however, treating institution also played a role. A considerable proportion of patients who underwent palliative or no radiotherapy were suitable for SABR treatment.

MTE24.02 Small Lung Tumours: High Risk Lesions and Contraindications to Stereotactic Ablative Body Radiotherapy (SABR)

The development of SABR has revolutionised the non-surgical treatment of small, node negative lung tumors, both primary and metastatic. SABR is a convenient, painless, inexpensive outpatient procedure and there is now randomized evidence that it not only results in better local control than conventionally fractionated radiotherapy in patients with inoperable peripheral stage I non-small cell lung cancer, but increases survival as well. The impressive local control rates of over 80% have tempted some investigators to expand the indications for high dose hypofractionated SABR beyond small peripheral tumors. Perhaps the most controversial extended indication is the use of SABR for “central” lung tumours. There is no agreed definition of what constitutes a central tumor, although in the absence of consensus, the “no-fly zone” described by Timmerman is widely used even though it was based on a very small number of events.1 Phase II trials have been interpreted as indicating that SABR of central tumors has acceptable toxicity (RTOG 0813), even though there was a 3% mortality likely resulting from treatment; or conversely as unsafe, with the Nordic HILUS trial reporting around 10% mortality after SABR of tumours close to the main or a lobar bronchus. The European Lung Tech trial should throw more light on the safety of treating central tumors with a “risk-adapted” approach using a more fractionated schedule of 60 Gy in 8 fractions.2 Many patients referred for SABR have poor respiratory or cardiac function making them unsuitable for surgical resection. Does this make them unsuitable for high dose SABR as well? The available evidence suggests not,3 but extreme caution should be taken in patients who have underlying interstitial lung disease.4 The relationship between SABR and cardiac injury, especially in the era of combined immunotherapy and SABR, remains under investigation. This high risk group of patients are currently eligible for the Stablemates trial, which is comparing sublobar resection with SABR. Eligibility includes FEV1 or DLCO < 50% predicted. A patient’s suitability for SABR will also depend on the dose constraints on nearby organs at risk. The chest wall is less concerning than previously, but is it the dose to the neurovascular bundle, rib or the whole musculoskeletal structure that most accurately predicts risk of chest wall pain? The brachial plexus tolerates hypofractionation poorly, and as with other scenarios where there is doubt about the safety of SABR, it is well to recognise that less effective but safer fully fractionated schedules are available. Other considerations, not in terms of risk, but of practical delivery of the treatment include synchronous multiple tumors, large tumors (>5 cm), and visibility for image guidance: Well defined? Too small? Image degraded by implanted fiducials? 1. Timmerman R, McGarry R, Yiannoutsos C, et al. Excessive Toxicity When Treating Central Tumors in a Phase II Study of Stereotactic Body Radiation Therapy for Medically Inoperable Early-Stage Lung Cancer. J Clin Oncol 2006;24:4833-9. 2. Adebahr S, Collette S, Shash E, et al. LungTech, an EORTC Phase II trial of stereotactic body radiotherapy for centrally located lung tumours: a clinical perspective. Br J Radiol 2015;88:20150036. 3. Guckenberger M, Kestin LL, Hope AJ, et al. Is there a lower limit of pretreatment pulmonary function for safe and effective stereotactic body radiotherapy for early-stage non-small cell lung cancer? J Thorac Oncol 2012;7:542-51. 4. Bahig H, Filion E, Vu T, et al. Severe radiation pneumonitis after lung stereotactic ablative radiation therapy in patients with interstitial lung disease. Pract Radiat Oncol 2016;6:367-74. Stereotactic ablative radiotherapy, contraindications

PC08.01 Debate #1: Locally Ablative Therapies Should Be Standard Treatment for Patients with NSCLC Oligometastese (PRO)

PC08.01 Debate #1: Locally Ablative Therapies Should Be Standard Treatment for Patients with NSCLC Oligometastese (PRO)

P2.16-17 Hypo-Fractionated Accelerated Radiotherapy in Central Early Non-Small Cell Lung Cancer: Leeds Cancer Centre Experience

Centrally located early stage lung cancers in patients who are unfit for surgery and stereotactic ablative body radiotherapy (SABR) are routinely treated with radical radiotherapy. There are no standard dose regimens but evidence seems to favour acceleration. We present the outcomes of a moderately hypo-fractionated accelerated dose regimen of 50Gy in 15 fractions (BED (a/b=10) corrected for time = 58.85Gy) from a single centre in the UK. Electronic case notes and radiotherapy records of lung cancer patients treated between January 2014 to December 2016 were retrospectively reviewed. Adult Comorbidity Evaluation-27 (ACE-27) score was used to evaluate comorbidities. Survival outcomes were estimated using Kaplan-Meier curves and compared using log-rank test. Fifty-three patients were treated with 50Gy in 15 fractions with a median age of 74.0 years (IQR: 69.5–79). 4 patients had a poor WHO PS of 3. Thirty-seven (69.8%) were females. A similar number had Grade 2 or 3 ACE-27 score while one had Grade 0. Forty-six patients were stage I, whilst four and three patients were stage II and III respectively. Thirty-seven (70%) patients had a radiological diagnosis. The treatment was well tolerated, 90-day mortality rate after radiotherapy was 3.8% (n=2). Grade 2 pneumonitis was seen in 5 patients while no grade 3 or 4 pneumonitis was observed. At the time of cut-off for analysis, the median follow-up was 20.2 months. The median progression-free survival (PFS) and overall survival (OS) were 18.5 months (95% CI 12.2–24.8) and 28.2 months (95%CI 14.4–42.1) respectively. The estimated 1 and 2 year PFS were 62.3% and 41.3% respectively and OS were 77.4% and 56.6% respectively. Only PS significantly impacted survival on univariate analysis, while PS and ACE-27 both were shown to have significant effect on multivariate analysis. Of the nineteen patients who relapsed, 4 (7.5%) had infield recurrence, 10 had out-of-field lung recurrence and the rest had distant metastases. One patient underwent salvage surgery. 6 patients received further radical therapy with 3 each being treated with conventional and SABR. This moderately hypo-fractionated accelerated radiotherapy regimen for central early stage lung cancer seems similar in efficacy but is associated with significantly less toxicity when compared to SABR.

P1.16-26 Safety of SABR (Stereotactic Ablative Body Radiotherapy) for Central Non-Small Cell Lung Cancers (cNSCLC) with 50 Gray in 5 Fractions (50Gy/5f)

P1.16-26 Safety of SABR (Stereotactic Ablative Body Radiotherapy) for Central Non-Small Cell Lung Cancers (cNSCLC) with 50 Gray in 5 Fractions (50Gy/5f)