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Background: Re-irradiation (re-RT) is a technically challenging task for which few standardized approaches exist. This is in part due to the lack of a common platform to assess dose tolerance in relation to toxicity in the re-RT setting. To better address this knowledge gap and provide new tools for studying and developing thresholds for re-RT, we developed a novel algorithm that allows for anatomically accurate three-dimensional mapping of composite biological effective dose (BED) distributions from nominal doses (Gy)., Methods: The algorithm was designed to automatically convert nominal dose from prior treatment plans to corresponding BED value maps (voxel size 2.5 mm 3 and α/β of 3 for normal tissue, BED 3 ). Following the conversion of each plan to a BED 3 dose distribution, deformable registration was used to create a summed composite re-irradiation BED 3 plan for each patient who received two treatments. A proof-of-principle analysis was performed on 38 re-irradiation cases of initial stereotactic ablative radiotherapy (SABR) followed by either re-SABR or chemoradiation for isolated locoregional recurrence of early-stage non-small cell lung cancer., Results: Evaluation of the algorithm-generated maps revealed appropriate conversion of physical dose to BED at each voxel. Of 14 patients receiving repeat SABR, there was one case each of grade 3 chest wall pain (7%), pneumonitis (7%), and dyspnea (7%). Of 24 patients undergoing repeat fractionated radiotherapy, grade 3 events were limited to two cases each of pneumonitis and dyspnea (8%). Composite BED 3 dosimetry for each patient who experienced grade 2-3 events is provided and may help guide development of precise cumulative dose thresholds for organs at risk in the re-RT setting., Conclusions: This novel algorithm successfully created a voxel-by-voxel composite treatment plan using BED values. This approach may be used to more precisely examine dosimetric predictors of toxicities and to establish more accurate normal tissue constraints for re-irradiation., (© 2021. The Author(s).)

Purpose: Management of synchronous early-stage non-small cell lung cancer (NSCLC) remains controversial because resection is not always feasible. This study evaluates efficacy and patterns of failure after SABR for synchronous early-stage NSCLC., Methods and Materials: From 2005 to 2015, patients presenting with ≥2 synchronous NSCLC tumors (T1a-T2b) and receiving SABR to ≥1 lesion were reviewed. The most common prescriptions were 50 Gy in 4 or 70 Gy in 10 fractions. Patients underwent multidisciplinary management with workup including chest computed tomography and positron emission tomography/computed tomography, plus brain imaging and endoscopic bronchial ultrasound for most patients to rule out mediastinal and distant disease. Synchronous lesions were defined as multiple ipsilateral or contralateral intrapulmonary lesions diagnosed within 6 months., Results: Of 912 patients treated with SABR for early-stage NSCLC at our institution, 82 (9%) presented with synchronous disease, with a total of 169 lesions. SABR was delivered to 142 lesions (84%), with 57 patients (69.5%) receiving SABR for all sites. Median overall survival (OS) and progression-free survival (PFS) were 5.1 and 2.7 years, respectively. At a median follow-up of 58 months, OS was 67% and 52% at 3 and 5 years, and corresponding PFS was 47% and 29%. Thirty-nine patients (48%) had progression, with 21 (26%) experiencing distant failure, and intralobar recurrence was among the first failure for 15 patients (18%). Of the 142 SABR-treated sites, these included 6 in-field (4%) and 4 marginal (3%) recurrences. There were no grade ≥3 adverse events. Among patients receiving SABR for all sites, there were no differences in OS (P = .946), PFS (P = .980), local control (P = .683), regional and distant control (P = .656), or toxicity (P = .791). On multivariable analysis, ipsilateral synchronous disease was associated with greater regional and distant failure (hazard ratio, 2.691; P = .025)., Conclusions: Synchronous NSCLC can be managed with definitive local therapy. With high control rates and favorable outcomes, SABR is an effective and feasible treatment for synchronous early-stage NSCLC., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Introduction: Patterns of local, regional, and distant failure after stereotactic ablative radiotherapy (SABR) for early-stage non-small cell lung cancer (NSCLC) have been widely reported. However, reliable methods for analyzing causes of local failure are lacking. We describe a method for analyzing and reporting patterns of in-field recurrence after SABR, incorporating dosimetric parameters from initial treatment plan as well as geometric information from diagnostic images at recurrence., Material and Methods: Diagnostic CT images at recurrence were registered with initial treatment planning images and radiation dose by deformable image registration. Recurrent gross tumor volume (rGTV) and centroid (geometric center of rGTV) were delineated. In-field failure was classified as centroids originating within the original planning target volume. Dose-volume histograms for each rGTV were used to further classify in-field recurrences as central high-dose (dose to 95% of rGTV [rGTVD95%] ≥95% of dose prescribed to PTV) or peripheral high-dose (rGTVD95% <95% of dose prescribed to PTV)., Results: 634 patients received SABR from 2004 to 2014 with 48 local recurrences. 35 of these had evaluable images with 16 in-field recurrences: 9 central high-dose, 6 peripheral high-dose, and 1 had both. Time to and volume of recurrence were not statistically different between central versus peripheral high-dose recurrences. However mean rGTV dose, mean centroid dose, and rGTVD95% were higher for central versus peripheral high-dose recurrences., Conclusion: We report a standardized method for analysis and classification of in-field recurrence after SABR. There were more central as opposed to peripheral high-dose recurrences, suggesting biological rather than technical issues underlying majority of in-field failures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Although isolated local (LRs) and regional recurrences (RRs) constitute a minority of post-stereotactic ablative radiotherapy (SABR) relapses, their management is becoming increasingly important as the use of SABR continues to expand. However, few evidence-based strategies are available to guide treatment of these potentially curable recurrences. On behalf of the Advanced Radiation Technology Committee of the International Association for the Study of Lung Cancer, this article was written to address management of recurrent disease. Topics discussed include diagnosis and workup, including the roles of volumetric and functional imaging as well as histopathologic methods; clinical outcomes after salvage therapy; patterns of recurrence after salvage therapy; and management options. Our main conclusions are that survival for patients with adequately salvaged LRs is similar to that for patients after primary SABR without recurrence, and survival for those with salvaged RRs (regardless of nodal burden or location) is similar to that of patients with de novo stage III disease. Although more than half of patients who undergo salvage do not develop a second relapse, the predominant pattern of second failure is distant, especially for RRs. Management requires rigorous multidisciplinary coordination. Isolated LRs can be managed with resection and nodal dissection, repeat SABR, thermal ablation, or systemic therapies. RRs can be treated with combined chemoradiotherapy, radiation or chemotherapy alone, or supportive services. Finally, regular and structured follow-up is recommended after post-SABR salvage therapy., (Copyright © 2019 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)

Purpose: Our purpose was to develop predictive nomograms for overall survival (OS), progression-free survival (PFS), and time-to-progression (TTP) at 5 years in patients with early-stage non-small cell lung cancer (ES-NSCLC) treated with stereotactic ablative radiation therapy (SABR)., Methods and Materials: The study cohort included 714 ES-NSCLC patients treated with SABR from 2004-2015 with median follow-up of 59 months, divided into training and testing sets (8:2), with the former used for nomogram development. The least absolute shrinkage and selection operator were initially employed to screen for predictors of OS, PFS, and TTP, and identified predictors were subsequently applied toward Cox proportional hazards regression modeling. Significant predictors (P < .05) on multivariable regression were then used to develop nomograms, which were validated via evaluation of concordance indexes (C-index) and calibration plots. Finally, Kaplan-Meier method and Gray's test were employed to compare and confirm differences in outcomes among various groups and explore prognostic factors associated with local versus distant disease progression., Results: Significant predictors of both OS and PFS at 5 years included age, sex, Charlson comorbidity index, diffusing capacity of carbon monoxide, systemic immune-inflammation index, and tumor size (P ≤ .01 for all). Eastern Cooperative Oncology Group performance status predicted for OS as well (P = .01), and both tumor size (P < .01) and minimum biological equivalent dose to 95% of planning target volume (PTV D95 BED 10 ; P < .01) were predictive of TTP. The C-indexes for the OS, PFS, and TTP nomograms were 0.73, 0.68, and 0.60 in the training data set and 0.72, 0.66, and 0.59 in the testing data set, respectively. Tumor size > 2.45 cm and PTV D95 BED 10 < 113 Gy were significantly associated with both local and distant progression., Conclusions: These prognostic nomograms can accurately predict for OS, PFS, and TTP at 5 years after SABR for ES-NSCLC and may thus help identify high-risk patients who could benefit from additional systemic therapy., (Published by Elsevier Inc.)

Introduction: Radiotherapy produces immune-promoting effects, which may be blunted by the delivery of corticosteroids (CS). We thus aimed to evaluate the impact of CS use on recurrence and survival outcomes of patients with early stage non-small-cell lung cancer treated with stereotactic ablative radiotherapy (SABR)., Materials and Methods: A prospectively registered database of patients with stage I to II (T1-3N0M0) stage non-small-cell lung cancer treated with SABR from 2004 to 2015 was queried. Concurrent CS administration was defined as receipt of CS within 2 days of the SABR course. Statistics included Kaplan-Meier survival analysis, Cox proportional hazards modeling, and cumulative incidence analysis utilizing death as a competing risk., Results: Of 912 patients, 87 (9.5%) received CS with their SABR course. The most common agent was prednisone (64.4%). Indications for CS use were chronic obstructive pulmonary disease in 53 cases (60.9%), chemotherapy in 7 (8.0%), arthritis in 7 (8.0%), chronic pain in 4 (4.6%), transplant-related in 3 (3.4%), and "others" in 13 (14.9%; pneumonia, asthma, anemia, etc.). The median follow-up time was 59.3 months. Compared with patients who did not receive CS, receipt of CS was associated with poorer overall survival (P = .004). However, CS administration was not associated with worse time to progression (P = .766) or any recurrence when using death as a competing risk (local P = .119, regional P = .449, distant P = .847, and any recurrence P = .708). Toxicity rates were not statistically different between cohorts., Conclusions: These data do not suggest increased recurrence rates when patients undergoing SABR are administered corticosteroids. However, owing to limitations of retrospective analyses, individualized judgment is still recommended., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Importance: Stereotactic ablative radiotherapy (SABR) is first-line treatment for patients with early-stage non-small cell lung cancer (NSCLC) who cannot undergo surgery. However, up to 1 in 6 such patients will develop isolated local recurrence (iLR) or isolated regional recurrence (iRR). Little is known about outcomes when disease recurs after SABR, or about optimal management strategies for such recurrences., Objective: To characterize long-term outcomes for patients with iLR or iRR after SABR for early-stage NSCLC with the aim of informing treatment decision making for these patients with potentially curable disease., Design, Setting, and Participants: In this cohort study, a retrospective review was conducted of 912 patients prospectively enrolled in an institutional database at a tertiary cancer center from January 1, 2004, through December 31, 2014., Main Outcomes and Measures: Overall survival, progression-free survival, recurrence patterns, demographics, salvage techniques, patterns of salvage failure, and toxic effects., Results: Of the 912 patients in the study (456 women and 456 men; median age, 72 years [range, 46-91 years]), 756 (82.9%) had T1 tumors at initial diagnosis; 502 tumors (55.0%) were adenocarcinomas and 309 tumors (33.9%) were squamous cell carcinomas. Of 912 patients with early-stage I to II NSCLC who received definitive SABR (50 Gy in 4 fractions or 70 Gy in 10 fractions), 102 developed isolated recurrence (49 with iLR and 53 with iRR), and 658 had no recurrence. Median times to recurrence after SABR were 14.5 months (range, 1.5-60.8 months) for iLR and 9.0 months (range, 1.9-70.7 months) for iRR; 39 of 49 patients (79.6%) with iLR and 48 of 53 patients (90.6%) with iRR underwent salvage with reirradiation, surgery, thermal ablation, or chemotherapy. Median follow-up times for patients with iLR or iRR were 57.2 months (interquartile range, 37.7-87.6 months) from initial SABR and 38.5 months (interquartile range, 19.9-69.3 months) from recurrence. Rates of overall survival at 5 years from initial SABR were no different between patients with iLR and salvage treatment (57.9%) and patients with no recurrence (54.9%; hazard ratio, 0.89; 95% CI, 0.56-1.43; P = .65) but were lower for patients with iRR and salvage treatment (31.1%; hazard ratio, 1.43; 95% CI, 1.00-2.34; P = .049). Patients receiving salvage treatment had longer overall survival than patients who did not (median, 37 vs 7 months after recurrence; hazard ratio, 0.40; 95% CI, 0.09-0.66; P = .006). Twenty-four of 87 patients (27.6%) who received salvage treatment for iLR or iRR subsequently developed distant metastases. No patient experienced grade 5 toxic effects after salvage treatment., Conclusions and Relevance: Life expectancy after salvage treatment for iLR was similar to that for patients without recurrence, but survival after salvage treatment for iRR was similar to that of patients with stage III NSCLC. Patients who received salvage treatment had significantly improved survival. Because salvage treatment for iLR or iRR was based on a consistent multidisciplinary approach, this may help in clinical decision making.

Background: The authors evaluated the efficacy, patterns of failure, and toxicity of stereotactic ablative radiotherapy (SABR) for patients with medically inoperable, clinical stage I non-small cell lung cancer (NSCLC) in a prospective clinical trial with 7 years of follow-up. Clinical staging was performed according to the seventh edition of the American Joint Committee on Cancer TNM staging system., Methods: Eligible patients with histologically confirmed NSCLC of clinical stage I as determined using positron emission tomography staging were treated with SABR (50 grays in 4 fractions). The primary endpoint was progression-free survival. Patients were followed with computed tomography and/or positron emission tomography/computed tomography every 3 months for the first 2 years, every 6 months for the next 3 years, and then annually thereafter., Results: A total of 65 patients were eligible for analysis. The median age of the patients was 71 years, and the median follow-up was 7.2 years. A total of 18 patients (27.7%) developed disease recurrence at a median of 14.5 months (range, 4.3-71.5 months) after SABR. Estimated incidences of local, regional, and distant disease recurrence using competing risk analysis were 8.1%, 10.9%, and 11.0%, respectively, at 5 years and 8.1%, 13.6%, and 13.8%, respectively, at 7 years. A second primary lung carcinoma developed in 12 patients (18.5%) at a median of 35 months (range, 5-67 months) after SABR. Estimated 5-year and 7-year progression-free survival rates were 49.5% and 38.2%, respectively; the corresponding overall survival rates were 55.7% and 47.5%, respectively. Three patients (4.6%) experienced grade 3 treatment-related adverse events. No patients developed grade 4 or 5 adverse events (toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 3.0])., Conclusions: With long-term follow-up, the results of the current prospective study demonstrated outstanding local control and low toxicity after SABR in patients with clinical stage I NSCLC. Regional disease recurrence and distant metastases were the dominant manifestations of failure. Surveillance for second primary lung carcinoma is recommended. Cancer 2017;123:3031-39. © 2017 American Cancer Society., (© 2017 American Cancer Society.)

Purpose: To discern the effectiveness and toxicity of stereotactic ablative radiation therapy (SABR) in the elderly population (aged ≥75 years) and to consider how SABR outcomes compare with surgical outcomes historically reported in the elderly., Methods and Materials: A total of 772 patients with clinical early-stage I-II non-small cell lung cancer (NSCLC; stage T1-T3N0M0) underwent SABR (50 Gy in 4 fractions or 70 Gy in 10 fractions) from 2004 to 2014 at our center (n=442, aged <75 years; n=330, aged ≥75 years). The primary endpoints included overall survival (OS), time-to-progression, and grade ≥3 toxicity. The median follow-up time was approximately 55 months., Results: Compared with patients aged <75 years, those aged ≥75 years had no difference in the time-to-progression (P=.419), lung cancer-specific survival (P=.275), or toxicity (P=.536). OS was the same between both age groups at 2 years of follow-up but diverged thereafter, with patients aged <75 years when treatment began having greater OS rates at 5 years. The median OS rates for patients aged ≥75 years were 86% at 1 year, 57.5% at 3 years, and 39.5% at 5 years. The median OS rates for patients aged <75 years were 87.3% at 1 year, 67.6% at 3 years, and 51.5% at 5 years. No patient aged ≥75 years experienced any grade 4 or 5 toxicity., Conclusions: The effectiveness of SABR was the same for the elderly as for the average-age population according to lung cancer-specific survival and time-to-progression. It also poses no increased toxicity. Compared with the historical outcomes with surgery in the elderly, SABR outcomes can be considered comparable for stage I-II disease but with less morbidity., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objectives: Our goal was to evaluate stereotactic ablative radiotherapy (SABR) as a salvage option for isolated recurrence of NSCLC in the lung parenchyma after definitive treatment of stage I to III disease., Methods: Patients who had histologically confirmed, positron emission tomography-staged, isolated NSCLC recurring locally or metastasis in the lung parenchyma (≤3 cm, suitable for SABR) after previous definitive treatment were prospectively enrolled in this trial and treated with volumetric, image-guided SABR to 50 Gy in four fractions. Patients were then followed with computed tomography or positron emission tomography/computed tomography. Primary end points included the pattern of failure after salvage SABR, overall survival (OS), and progression-free survival (PFS)., Results: Fifty-nine patients with recurrent disease were treated with salvage SABR. The median age was 70 years (range 45-86 years), and the median follow-up time after salvage SABR was 58.3 months. Re-recurrence after salvage SABR developed in 19 patients (32%). Measuring from the date of salvage SABR, the estimated 5-year rates of local, regional, and distant failure were 5.2%, 10.3%, and 22.4%, respectively; the estimated PFS was 46.2% at 3 years and 41.1% at 5 years; and the OS rates were 63.5% at 3 years and 56.5% at 5 years. A high post-SABR neutrophil-to-lymphocyte ratio was found to predict poor survival. Grade 3 treatment-related adverse events developed in three patients (5%). No patient had a grade 4 or 5 event., Conclusion: Our study showed that salvage SABR provides excellent 5-year OS, local control, and PFS rates with minimal toxicity for patients with isolated NSCLC recurrence in the lung parenchyma. These results are striking and comparable to historically reported outcomes of patients with primary early-stage NSCLC treated with definitive SABR. SABR appears to be a very effective and safe salvage option for patients with isolated lung parenchyma recurrent disease after definitive treatment and should be considered along with surgery as a potential first-line option for patients with local lung parenchymal recurrent disease., (Copyright © 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)