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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Stereotactic Radiosurgery for Patients With Brain Metastases From Small Cell Lung Cancer

Background: Patients with small-cell lung cancer have a high likelihood of developing brain metastases. Many of these patients will have prophylactic cranial irradiation (PCI) or eventually undergo whole brain radiation therapy (WBRT). Despite these treatments, a large number of these patients will have progression of their intracranial disease and require additional local therapy. Stereotactic radiosurgery (SRS) is an important treatment option for such patients. Methods: We retrospectively reviewed the charts of 44 patients with brain metastases from small-cell lung cancer treated with gamma knife SRS. Multivariate analysis was used to determine significant prognostic factors influencing survival. Results: The median follow-up from SRS in this patient population was 9 months (1-49 months). The median overall survival (OS) was 9 months after SRS. Karnofsky performance status (KPS) and combined treatment involving WBRT and SRS within 4 weeks were the two factors identified as being significant predictors of increased OS (p = 0.033 and 0.040, respectively). When comparing all patients, patients treated with a combined approach had a median OS of 14 months compared to 6 months if SRS was delivered alone. We also compared the OS times from the first definitive radiation: WBRT, WBRT and SRS if combined therapy was used, and SRS if the patient never received WBRT. The median survival for those groups was 12, 14, and 13 months, respectively, p = 0.19. Seventy percent of patients had follow-up magnetic resonance imaging available for review. Actuarial local control at 6 months and 12 months was 90% and 86%, respectively. Only 1 patient (2.2%) had symptomatic intracranial swelling related to treatment, which responded to a short course of steroids. New brain metastases outside of the treated area developed in 61% of patients at a median time of 7 months; 81% of these patients had received previous WBRT. Conclusions: Stereotactic radiosurgery for small-cell lung carcinoma brain metastases provided safe and effective local tumor control in the majority of patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Quality Assurance Analysis of a Large Multicenter Practice: Does Increased Complexity of Intensity-Modulated Radiotherapy Lead to Increased Error Frequency?

Purpose: Error reduction is an important concern in clinical medicine. Intensity-modulated radiotherapy (IMRT) is an important advancement in radiation oncology that increases the complexity of treatment, potentially increasing the error risk. We studied the frequency and severity of errors in a large multicenter practice to ascertain the impact of quality improvement interventions over time, IMRT, and type of practice. Methods and Materials: We analyzed prospective data from three academic and 16 community practice sites with 24,775 courses of radiotherapy (9,210 IMRT courses and 15,565 non-IMRT) between January 2006 and December 2009. All IMRT treatment was performed using one centralized dose planning center for all sites. Results: We prospectively identified various errors or potential errors in 0.14 % vs. 0.40 % of the IMRT vs. non-IMRT courses (13/9,210 vs. 62/15,565, p = 0.0004) and excluding potential errors: 0.03 % for IMRT vs. 0.21% for non-IMRT. We developed the Clinical Radiotherapy Error Severity Scale (CRESS) to classify error severity from 1 to 10, with 1 to 3 for potential or completely correctable errors, 4 to 5 for dose variations <5%, and 6 to 10 for dose variations >5%. Multivariate analyses of CRESS values, severity >4, and any error (including potential) correlated significantly reduced errors with IMRT (p = 0.0001-0.0024) but found no significant difference between the academic and community practice sites and no change in error frequency over time despite implementation of 39 system-wide policy changes by the centralized quality improvement committee. Conclusions: Despite the increase in complexity with IMRT compared with conventional radiotherapy, it can be delivered with reduced error frequency.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2011

Gleason Pattern 5 Is the Greatest Risk Factor for Clinical Failure and Death From Prostate Cancer After Dose-Escalated Radiation Therapy and Hormonal Ablation

Purpose: The division of Gleason score (GS) into three categories (2-6, 7, 8-10) may not fully use its prognostic power, as revealed by recent reports demonstrating the presence of Gleason Pattern 5 (GP5) as a strong predictor for biochemical recurrence. Therefore, we analyzed the clinical outcomes in patients treated with dose-escalated radiation therapy (RT) based on the presence or absence of GP5. Methods and Materials: Outcomes were analyzed for 718 men treated for localized prostate cancer with external-beam RT to a minimum planning target volume dose of at least 75 Gy. We assessed the impact of GP5 and that of pretreatment- and treatment-related factors on freedom from biochemical failure, freedom from metastasis (FFM), cause-specific survival (CSS), and overall survival (OS). Results: At biopsy, 89% of patients had no GP5, and 11% (76/718) had GP5. There were no differences in age, comorbid illness, T stage, prostate-specific antigen, or the use or duration of androgen deprivation therapy between GS8 without GP5 and GS8-10 with GP5. The presence of GP5 predicted lower FFM (p < 0.002; hazard ratio [HR] 3.4 [1.7-7.1]); CSS (p < 0.0001; HR 12.9 [5.4-31]); and OS (p < 0.0001; HR 3.6 [2.0-6.5]) in comparison with GS8 (without GP5). The 8-year FFM, CSS, and OS were 89%, 98%, and 57%, respectively, for those with Gleason 8 prostate cancer without GP5 in comparison with 61%, 55%, and 31%, respectively, for those with GP5. In addition, both FFM and CSS were strongly influenced by androgen deprivation therapy given concurrently with RT. On multivariate analysis, GP5 was the strongest prognostic factor for all clinical endpoints, including OS. Conclusion: The presence of GP5 predicts for worse clinical behavior, which therefore needs to be accounted for by risk stratification schemes. Further intensification of local and/or systemic therapy may be appropriate for such patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Evaluation of Dosimetric Consequences of Seroma Contour Variability in Accelerated Partial Breast Irradiation Using a Constructed Representative Seroma Contour

Purpose: Contouring variability of the seroma can have important implications in the planning and delivery of accelerated partial breast irradiation (APBI). This study aimed to quantify the dosimetric impact of these interobserver and intraobserver contouring variations by construction of a representative seroma contour (RSC). Methods and Materials: Twenty-one patients with a seroma suitable for APBI underwent four computed tomography (CT) scans: one planning CT and three additional CTs on the first, third, and fifth days of treatment. Three radiation oncologists contoured the seroma on each CT scan. For 3 patients, oncologists repeated contouring twice to assess intraobserver variations. Seroma contour variability was quantified by construction of an RSC. In addition, the percent volume overlap (PVO) was calculated. Root-mean-square (RMS) differences in seroma volume, size, and center of mass position compared to those of the RSC were calculated. Treatment fields from the original plan were applied to the repeated CTs by using the same isocenter shifts as the original plan. The dosimetric impact of the contour variations was assessed using V{sub 95} (volume receiving at least 95% of the prescribed dose) and equivalent uniform dose (EUD). Results: Interobserver RMS volume differences were, on average, 5.6 times larger than intraobserver differences. The median interobserver RMS seroma volume difference was 1.48 cm{sup 3}. The median PVO was 51.6%. V{sub 95} and EUD of the seroma contours were similar for all patients. The median RMS differences of the seroma V{sub 95} and EUD were 0.01% (range, 0%-3.99%) and 0.05 Gy (range, 0-0.98 Gy). Conclusions: Construction of the RSC showed that interobserver variations were most responsible for contour variations of the seroma. Current planning margins provided adequate dose coverage of the seroma despite these contour variations.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Current Dosing Paradigm for Stereotactic Radiosurgery Alone After Surgical Resection of Brain Metastases Needs to Be Optimized for Improved Local Control

Purpose: To describe the use of radiosurgery (RS) alone to the resection cavity after resection of brain metastases as an alternative to adjuvant whole-brain radiotherapy (WBRT). Methods and Materials: Sixty-two patients with 64 cavities were treated with linear accelerator-based RS alone to the resection cavity after surgical removal of brain metastases between March 2007 and August 2010. Fifty-two patients (81%) had a gross total resection. Median cavity volume was 8.5 cm{sup 3}. Forty-four patients (71%) had a single metastasis. Median marginal and maximum doses were 18 Gy and 20.4 Gy, respectively. Sixty-one cavities (95%) had gross tumor volume to planning target volume expansion of {>=}1 mm. Results: Six-month and 1-year actuarial local recurrence rates were 14% and 22%, respectively, with a median follow-up period of 9.7 months. Six-month and 1-year actuarial distant brain recurrence, total intracranial recurrence, and freedom from WBRT rates were 31% and 51%, 41% and 63%, and 91% and 74%, respectively. The symptomatic cavity radiation necrosis rate was 8%, with 2 patients (3%) undergoing surgery. Of the 11 local failures, 8 were in-field, 1 was marginal, and 2 were both (defined as in-field if {>=}90% of recurrence within the prescription isodose and marginal if {>=}90% outside of the prescription isodose). Conclusions: The high rate of in-field cavity failure suggests that geographic misses with highly conformal RS are not a major contributor to local recurrence. The current dosing regimen derived from Radiation Therapy Oncology Group protocol 90-05 should be optimized in this patient population before any direct comparison with WBRT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Age and Comorbid Illness Are Associated With Late Rectal Toxicity Following Dose-Escalated Radiation Therapy for Prostate Cancer

Purpose: To assess the impacts of patient age and comorbid illness on rectal toxicity following external beam radiation therapy (EBRT) for prostate cancer and to assess the Qualitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) normal tissue complication probability (NTCP) model in this context. Methods and Materials: Rectal toxicity was analyzed in 718 men previously treated for prostate cancer with EBRT (≥75 Gy). Comorbid illness was scored using the Charlson Comorbidity Index (CCMI), and the NTCP was evaluated with the QUANTEC model. The influence of clinical and treatment-related parameters on rectal toxicity was assessed by Kaplan-Meier and Cox proportional hazards models. Results: The cumulative incidence of rectal toxicity grade ≥2 was 9.5% and 11.6% at 3 and 5 years and 3.3% and 3.9% at 3 and 5 years for grade ≥3 toxicity, respectively. Each year of age predicted an increasing relative risk of grade ≥2 (P<.03; hazard ratio [HR], 1.04 [95% confidence interval (CI), 1.01-1.06]) and ≥3 rectal toxicity (P<.0001; HR, 1.14 [95% CI,1.07-1.22]). Increasing CCMI predicted rectal toxicity where a history of either myocardial infarction (MI) (P<.0001; HR, 5.1 [95% CI, 1.9-13.7]) or congestive heart failure (CHF) (P<.0006; HR, 5.4 [95% CI, 0.6-47.5]) predicted grade ≥3 rectal toxicity, with lesser correlation with grade ≥2 toxicity (P<.02 for MI, and P<.09 for CHF). An age comorbidity model to predict rectal toxicity was developed and confirmed in a validation cohort. The use of anticoagulants increased toxicity independent of age and comorbidity. NTCP was prognostic for grade ≥3 (P=.015) but not grade ≥2 (P=.49) toxicity. On multivariate analysis, age, MI, CHF, and an NTCP >20% all correlated with late rectal toxicity. Conclusions: Patient age and a history of MI or CHF significantly impact rectal toxicity following EBRT for the treatment of prostate cancer, even after controlling for NTCP.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Retrospective Evaluation Reveals That Long-term Androgen Deprivation Therapy Improves Cause-Specific and Overall Survival in the Setting of Dose-Escalated Radiation for High-Risk Prostate Cancer

Purpose: To evaluate the role of androgen deprivation therapy (ADT) and duration for high-risk prostate cancer patients treated with dose-escalated radiation therapy (RT). Methods and Materials: A retrospective analysis of high-risk prostate cancer patients treated with dose-escalated RT (minimum 75 Gy) with or without ADT was performed. The relationship between ADT use and duration with biochemical failure (BF), metastatic failure (MF), prostate cancer-specific mortality (PCSM), non-prostate cancer death (NPCD), and overall survival (OS) was assessed as a function of pretreatment characteristics, comorbid medical illness, and treatment using Fine and Gray's cumulative incidence methodology. Results: The median follow-up time was 64 months. In men with National Comprehensive Cancer Network defined high-risk prostate cancer treated with dose-escalated RT, on univariate analysis, both metastasis (P<.0001; hazard ratio 0.34; 95% confidence interval 0.18-0.67; cumulative incidence at 60 months 13% vs 35%) and PCSM (P=.015; hazard ratio 0.41; 95% confidence interval 0.2-1.0; cumulative incidence at 60 months 6% vs 11%) were improved with the use of ADT. On multivariate analysis for all high-risk patients, Gleason score was the strongest negative prognostic factor, and long-term ADT (LTAD) improved MF (P=.002), PCSM (P=.034), and OS (P=.001). In men with prostate cancer and Gleason scores 8 to 10, on multivariate analysis after adjustment for other risk features, there was a duration-dependent improvement in BF, metastasis, PCSM, and OS, all favoring LTAD in comparison with STAD or RT alone. Conclusion: For men with high-risk prostate cancer treated with dose-escalated EBRT, this retrospective study suggests that the combination of LTAD and RT provided a significant improvement in clinical outcome, which was especially true for those with Gleason scores of 8 to 10.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Outcomes and Patterns of Failure for Grade 2 Meningioma Treated With Reduced-Margin Intensity Modulated Radiation Therapy

Purpose: The purpose of this study was to evaluate intracranial control and patterns of local recurrence (LR) for grade 2 meningiomas treated with intensity modulated radiation therapy (IMRT) with limited total margin expansions of ≤1 cm. Methods and Materials: We reviewed records of patients with a neuropathological diagnosis of grade 2 meningioma who underwent IMRT at our institution between 2002 and 2012. Actuarial rates were determined by the Kaplan-Meier method from the end of RT. LR was defined as in-field if ≥90% of the recurrence was within the prescription isodose, out-of-field (marginal) if ≥90% was outside of the prescription isodose, and both if neither criterion was met. Results: Between 2002 and 2012, a total of 54 consecutive patients underwent IMRT for grade 2 meningioma. Eight of these patients had total initial margins >1 cm and were excluded, leaving 46 patients for analysis. The median imaging follow-up period was 26.2 months (range, 7-107 months). The median dose for fractionated IMRT was 59.4 Gy (range, 49.2-61.2 Gy). Median clinical target volume (CTV), planning target volume (PTV), and total margin expansion were 0.5 cm, 0.3 cm, and 0.8 cm, respectively. LR occurred in 8 patients (17%), with 2-year and 3-year actuarial local control (LC) of 92% and 74%, respectively. Six of 8 patients (85%) had a known pattern of failure. Five patients (83%) had in-field LR; no patients had marginal LR; and 1 patient (17%) had both. Conclusions: The use of IMRT to treat grade 2 meningiomas with total initial margins (CTV + PTV) ≤1 cm did not appear to compromise outcomes or increase marginal failures compared with other modern retrospective series. Of the 46 patients who had margins ≤1 cm, none experienced marginal failure only. These results demonstrate efficacy and low risk of marginal failure after IMRT treatment of grade 2 meningiomas with reduced margins, warranting study within a prospective clinical trial.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Should Women Younger Than 40 Years of Age With Invasive Breast Cancer Have a Mastectomy?: 15-Year Outcomes in a Population-Based Cohort

Purpose: Optimal local management for young women with early-stage breast cancer remains controversial. This study examined 15-year outcomes among women younger than 40 years treated with breast-conserving surgery plus whole-breast radiation therapy (BCT) compared with those treated with modified radical mastectomy (MRM). Methods and Materials: Women aged 20 to 39 years with early-stage breast cancer diagnosed between 1989 and 2003 were identified in a population-based database. Primary outcomes of breast cancer–specific survival (BCSS), overall survival (OS) and secondary outcomes of local relapse–free survival (LRFS), locoregional relapse–free survival (LRRFS), and distant relapse–free survival (DRFS) were calculated using Kaplan-Meier methods and compared between BCT and MRM cohorts using log-rank tests. A planned subgroup analysis was performed on patients considered “ideal” for BCT (ie, T1N0, negative margins and no extensive ductal carcinoma in situ) and in whom local therapy may have the largest impact on survival because of low systemic risk. Results: 965 patients were identified; 616 had BCT and 349 had MRM. The median follow-up time was 14.4 years (range, 8.4-23.3 years). Overall, 15-year rates of BCSS (76.0% vs 74.1%, P=.62), OS (74.2% vs 73.0%, P=.75), LRFS (85.4% vs 86.5%, P=.95), LRRFS (82.2% vs 81.6%, P=.61), and DRFS (74.4% vs 71.6%, P=.40) were similar between the BCT and MRM cohorts. In the “ideal” for BCT subgroup, there were 219 BCT and 67 MRM patients with a median follow-up time of 15.5 years. The 15-year BCSS (86.1% vs 82.9%, P=.57), OS (82.6% vs 82.9%, P=.89), LRFS (86.2% vs 84.2%, P=.50), LRRFS (83.1% vs 78.3%, P=.24), and DRFS (84.8% vs 79.1%, P=.17) were similar in the BCT and MRM cohorts. Conclusions: This population-based analysis with long-term follow-up confirmed that women younger than 40 years treated with BCT had similar 15-year outcomes compared with MRM. Young age alone is not a contraindication to BCT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Second Malignancies After Adjuvant Radiation Therapy for Early Stage Breast Cancer: Is There Increased Risk With Addition of Regional Radiation to Local Radiation?

Purpose: This study was undertaken to determine whether there was an increased risk of second malignancies (SM), particularly lung cancer, in early stage breast cancer patients treated with the addition of nodal fields to breast and/or chest wall radiation therapy (RT). Materials and Methods: Subjects were stage I/II female breast cancer patients 20 to 79 years of age, diagnosed between 1989 and 2005 and treated with adjuvant RT at our institution. Patients were included if they survived and did not have SM within 3 years of diagnosis. Standardized incidence ratios (SIR) with 95% confidence intervals (CI) were calculated to compare SM incidence to cancer incidence in the general sex- and age-matched populations. Secondary malignancy risks in patients treated with local RT (LRT) to the breast/chest wall were compared to those in patients treated with locoregional RT (LRRT) to the breast/chest wall and regional nodes, using multivariate regression analysis (MVA) to account for covariates. Results: The cohort included 12,836 patients with a median follow-up of 8.4 years. LRRT was used in 18% of patients. The SIR comparing patients treated with LRT to the general population was 1.29 (CI: 1.21-1.38). No statistically significant increased incidence of in-field malignancies (SIR, 1.04; CI: 0.87-1.23) and lung cancers (SIR, 1.06; CI: 0.88-1.26) was detected. The SIR comparing patients treated with LRRT to the general population was 1.39 (CI: 1.17-1.64). No statistically significant increased incidence of in-field malignancies (SIR, 1.26; CI: 0.77-1.94) and lung cancers (SIR, 1.27; CI: 0.76-1.98) was detected. On MVA comparing LRRT to LRT, the adjusted hazard ratio was 1.20 for in-field malignancies (CI: 0.68-2.16) and 1.26 for lung cancer (CI: 0.67-2.36). The excess attributable risk (EAR) to regional RT was 3.1 per 10,000 person years (CI: −8.7 to 9.9). Conclusions: No statistically significant increased risk of second malignancy was detected after LRRT relative to that for LRT. The upper limit of the EAR was approximately 1% at 10 years.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Phase 2 Trial of De-intensified Chemoradiation Therapy for Favorable-Risk Human Papillomavirus–Associated Oropharyngeal Squamous Cell Carcinoma

Purpose: To perform a prospective, multi-institutional, phase 2 study of a substantial decrease in concurrent chemoradiation therapy (CRT) intensity as primary treatment for favorable-risk, human papillomavirus–associated oropharyngeal squamous cell carcinoma. Methods and Materials: The major inclusion criteria were: (1) T0 to T3, N0 to N2c, M0; (2) human papillomavirus or p16 positive; and (3) minimal/remote smoking history. Treatment was limited to 60 Gy intensity modulated radiation therapy with concurrent weekly intravenous cisplatinum (30 mg/m{sup 2}). The primary study endpoint was pathologic complete response (pCR) rate based on required biopsy of the primary site and dissection of pretreatment positive lymph node regions, regardless of radiographic response. Power computations were performed for the null hypothesis that the pCR rate is 87% and n=40, resulting in a type 1 error of 14.2%. Secondary endpoint measures included physician-reported toxicity (Common Toxicity Terminology for Adverse Events, CTCAE), patient-reported symptoms (PRO-CTCAE), and modified barium swallow studies. Results: The study population was 43 patients. The pCR rate was 86% (37 of 43). The incidence of CTCAE grade 3/4 toxicity and PRO-CTCAE severe/very severe symptoms was as follows: mucositis 34%/45%, general pain 5%/48%, nausea 18%/52%, vomiting 5%/34%, dysphagia 39%/55%, and xerostomia 2%/75%. Grade 3/4 hematologic toxicities were 11%. Thirty-nine percent of patients required a feeding tube for a median of 15 weeks (range, 5-22 weeks). There were no significant differences in modified barium swallow studies before and after CRT. Conclusions: The pCR rate with decreased intensity of therapy with 60 Gy of IMRT and weekly low-dose cisplatinum is very high in favorable-risk oropharyngeal squamous cell carcinoma, with evidence of decreased toxicity compared with standard therapies. (ClinicalTrials.gov) ID: (NCT01530997).

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Volumetric Radiosurgery for 1 to 10 Brain Metastases: A Multicenter, Single-Arm, Phase 2 Study

Purpose: Interest is growing in treating multiple brain metastases with radiosurgery. We report on the effectiveness and tolerability of volumetric radiosurgery (VRS). Methods and Materials: We enrolled patients with a ≥6-month estimated life expectancy and 1 to 10 brain metastases with a diameter of ≤3 cm at 5 cancer centers. Volumetric radiosurgery was delivered in 5 fractions with 98% target coverage, prescribed as 95% of 50 Gy (47.5 Gy in 5 fractions) to the metastases with no margin and 95% of 40 Gy (38 Gy in 5 fractions) to their 2-mm planning target volumes, concurrent with 20 Gy to the whole brain planning target volume. The treatment was delivered with daily image guidance using conventional linear accelerators and volumetric modulated arc therapy. A magnetic resonance imaging scan was obtained every 3 months. The primary endpoint was the 3-month objective response in the brain according to the Response Evaluation Criteria in Solid Tumors, version 1.1. The principal secondary endpoint was 1-year actuarial control of treated metastases. Toxicities were graded using the Common Terminology Criteria for Adverse Events, version 4.0. The present study is registered with (ClinicalTrials.gov) ( (clinicaltrials.gov) identifier (NCT01046123)). Results: From July 2010 to May 2013, 60 patients underwent VRS with 47.5 Gy in 5 fractions for 12 metastases in the thalamus and basal ganglia (deep metastases) and 207 non-deep metastases. The median follow-up period was 30.5 months, and the median survival was 10.1 months. For the 43 patients assessable at 3 months, the objective response in the brain was 56%. The treated metastases were controlled in 88% of patients at 1 year and 84% at 3 years. Overall survival did not differ for patients with 4 to 10 versus 1 to 3 metastases (hazard ratio 1.18, P=.6). The crude incidence of severe radionecrosis (grade 3-5) was 25% (3 of 12) per deep metastasis, 1.9% (4 of 219) per non-deep metastasis, and 10% (6 of 60) per patient. Conclusions: For non-deep brain metastases, 47.5 Gy in 5 fractions was tolerable. Volumetric radiosurgery was effective for long-term control of treated brain metastases.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Surgical Resection of Brain Metastases and the Risk of Leptomeningeal Recurrence in Patients Treated With Stereotactic Radiosurgery

Purpose: Recent prospective data have shown that patients with solitary or oligometastatic disease to the brain may be treated with upfront stereotactic radiosurgery (SRS) with deferral of whole-brain radiation therapy (WBRT). This has been extrapolated to the treatment of patients with resected lesions. The aim of this study was to assess the risk of leptomeningeal disease (LMD) in patients treated with SRS to the postsurgical resection cavity for brain metastases compared with patients treated with SRS to intact metastases. Methods and Materials: Four hundred sixty-five patients treated with SRS without upfront WBRT at a single institution were identified; 330 of these with at least 3 months' follow-up were included in this analysis. One hundred twelve patients had undergone surgical resection of at least 1 lesion before SRS compared with 218 treated for intact metastases. Time to LMD and overall survival (OS) time were estimated from date of radiosurgery, and LMD was analyzed by the use of cumulative incidence method with death as a competing risk. Univariate and multivariate analyses were performed with competing risk regression to determine whether various clinical factors predicted for LMD. Results: With a median follow-up time of 9.0 months, 39 patients (12%) experienced LMD at a median of 6.0 months after SRS. At 1 year, the cumulative incidence of LMD, with death as a competing risk, was 5.2% for the patients without surgical resection versus 16.9% for those treated with surgery (Gray test, P<.01). On multivariate analysis, prior surgical resection (P<.01) and breast cancer primary (P=.03) were significant predictors of LMD development. The median OS times for patients undergoing surgery compared with SRS alone were 12.9 and 10.6 months, respectively (log-rank P=.06). Conclusions: In patients undergoing SRS with deferral of upfront WBRT for intracranial metastatic disease, prior surgical resection and breast cancer primary are associated with an increased risk for the development of LMD.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Safety and Efficacy of Radiation Therapy in Advanced Melanoma Patients Treated With Ipilimumab

Purpose: Ipilimumab and radiation therapy (RT) are standard treatments for advanced melanoma; preclinical models suggest the potential for synergy. However, limited clinical information exists regarding safety and optimal timing of the combination. Methods and Materials: We reviewed the records of consecutive patients with unresectable stage 3 or 4 melanoma treated with ipilimumab. Patients were categorized as having received RT or not. Differences were estimated between these 2 cohorts. Results: We identified 88 patients treated with ipilimumab. At baseline, the ipilimumab-plus-RT group (n=44) had more unfavorable characteristics. Despite this, overall survival, progression-free survival, and both immune-related and non–immune-related toxicity were not statistically different (P=.67). Patients who received ipilimumab before RT had an increased duration of irradiated tumor response compared with patients receiving ipilimumab after RT (74.7% vs 44.8% at 12 months; P=.01, log-rank test). In addition, patients receiving ablative RT had non–statistically significantly improved median overall survival (19.6 vs 10.2 months), as well as 6-month (95.1% vs 72.7%) and 12-month (79.7% vs 48.5%) survival rates, compared with those treated with conventionally fractionated RT. Conclusions: We found that both ablative and conventionally fractionated RT can be safely administered with ipilimumab without a clinically apparent increase in toxicity. Patients who received ipilimumab before RT had an increased duration of irradiated tumor response.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Programmatic Comparison and Dissemination of an Audit of Single-fraction Radiation Therapy Prescribing Practices for Bone Metastases is Associated with a Meaningful and Lasting Change in Practice on a Population Level

There is ample evidence that single-fraction radiation therapy (SFRT) is as efficacious as more costly and morbid multifraction regimens. We previously demonstrated that an audit-based intervention increased the use of SFRT in all regional cancer centers the following year. However, other investigators have demonstrated that interventions were only associated with a transient 1-year change in prescribing practices. We sought to determine whether our intervention resulted in a more lasting impact.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Is SABR Cost-Effective in Oligometastatic Cancer? An Economic Analysis of the SABR-COMET Randomized Trial

The phase 2 randomized study SABR-COMET demonstrated that in patients with controlled primary tumors and 1 to 5 oligometastatic lesions, SABR was associated with improved progression-free survival (PFS) compared with standard of care (SoC), but with higher costs and treatment-related toxicities. The aim of this study was to assess the cost-effectiveness of SABR versus SoC in this setting.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Clinicopathologic and Transcriptomic Analysis of Radiation-Induced Lung Injury in Nonhuman Primates

Radiation-induced lung injury (RILI) is a progressive condition with an early phase (radiation pneumonitis) and a late phase (lung fibrosis). RILI may occur after partial-body ionizing radiation exposures or internal radioisotope exposure, with wide individual variability in timing and extent of lung injury. This study aimed to provide new insights into the pathogenesis and progression of RILI in the nonhuman primate (NHP) rhesus macaque model.

62 RADIOLOGY AND NUCLEAR MEDICINE↗