A quantitative framework for patient-specific collision detection in proton therapy.

BACKGROUND: Beam modifying accessories for proton therapy often need to be placed in close proximity of the patient for optimal dosimetry. However, proton treatment units are larger in size and as a result the planned treatment geometry may not be achievable due to collisions with the patient. A framework that can accurately simulate proton treatment geometry is desired. PURPOSE: A quantitative framework was developed to model patient-specific proton treatment geometry, minimize air gap, and avoid collisions. METHODS: The patient's external contour is converted into the International Electrotechnique Commission (IEC) gantry coordinates following the patient's orientation and each beam's gantry and table angles. All snout components are modeled by three-dimensional (3D) geometric shapes such as columns, cuboids, and frustums. Beam-specific parameters such as isocenter coordinates, snout type and extension are used to determine if any point on the external contour protrudes into the various snout components. A 3D graphical user interface is also provided to the planner to visualize the treatment geometry. In case of a collision, the framework's analytic algorithm quantifies the maximum protrusion of the external contour into the snout components. Without a collision, the framework quantifies the minimum distance of the external contour from the snout components and renders a warning if such distance is less than 5 cm. RESULTS: Three different snout designs are modeled. Examples of potential collision and its aversion by snout retraction are demonstrated. Different patient orientations, including a sitting treatment position, as well as treatment plans with multiple isocenters, are successfully modeled in the framework. Finally, the dosimetric advantage of reduced air gap enabled by this framework is demonstrated by comparing plans with standard and reduced air gaps. CONCLUSION: Implementation of this framework reduces incidence of collisions in the treatment room. In addition, it enables the planners to minimize the air gap and achieve better plan dosimetry.

Genome-wide enriched pathway analysis of acute post-radiotherapy pain in breast cancer patients: a prospective cohort study.

BACKGROUND: Adjuvant radiotherapy (RT) can increase the risk of developing pain; however, the molecular mechanisms of RT-related pain remain unclear. The current study aimed to identify susceptibility loci and enriched pathways for clinically relevant acute post-RT pain, defined as having moderate to severe pain (pain score ≥ 4) at the completion of RT. METHODS: We conducted a genome-wide association study (GWAS) with 1,344,832 single-nucleotide polymorphisms (SNPs), a gene-based analysis using PLINK set-based tests of 19,621 genes, and a functional enrichment analysis of a gene list of 875 genes with p < 0.05 using NIH DAVID functional annotation module with KEGG pathways and GO terms (n = 380) among 1112 breast cancer patients. RESULTS: About 29% of patients reported acute post-RT pain. None of SNPs nor genes reached genome-wide significant level. Four SNPs showed suggestive associations with post-RT pain; rs16970540 in RFFL or near the LIG3 gene (p = 1.7 × 10-6), rs4584690, and rs7335912 in ABCC4/MPR4 gene (p = 5.5 × 10-6 and p = 7.8 × 10-6, respectively), and rs73633565 in EGFL6 gene (p = 8.1 × 10-6). Gene-based analysis suggested the potential involvement of neurotransmitters, olfactory receptors, and cytochrome P450 in post-RT pain, whereas functional analysis showed glucuronidation (FDR-adjusted p value = 9.46 × 10-7) and olfactory receptor activities (FDR-adjusted p value = 0.032) as the most significantly enriched biological features. CONCLUSIONS: This is the first GWAS suggesting that post-RT pain is a complex polygenic trait influenced by many biological processes and functions such as glucuronidation and olfactory receptor activities. If validated in larger populations, the results can provide biological targets for pain management to improve cancer patients' quality of life. Additionally, these genes can be further tested as predictive biomarkers for personalized pain management.

Postoperative stereotactic radiosurgery compared with whole brain radiotherapy for resected metastatic brain disease (NCCTG N107C/CEC·3): a multicentre, randomised, controlled, phase 3 trial.

BACKGROUND: Whole brain radiotherapy (WBRT) is the standard of care to improve intracranial control following resection of brain metastasis. However, stereotactic radiosurgery (SRS) to the surgical cavity is widely used in an attempt to reduce cognitive toxicity, despite the absence of high-level comparative data substantiating efficacy in the postoperative setting. We aimed to establish the effect of SRS on survival and cognitive outcomes compared with WBRT in patients with resected brain metastasis. METHODS: In this randomised, controlled, phase 3 trial, adult patients (aged 18 years or older) from 48 institutions in the USA and Canada with one resected brain metastasis and a resection cavity less than 5·0 cm in maximal extent were randomly assigned (1:1) to either postoperative SRS (12-20 Gy single fraction with dose determined by surgical cavity volume) or WBRT (30 Gy in ten daily fractions or 37·5 Gy in 15 daily fractions of 2·5 Gy; fractionation schedule predetermined for all patients at treating centre). We randomised patients using a dynamic allocation strategy with stratification factors of age, duration of extracranial disease control, number of brain metastases, histology, maximal resection cavity diameter, and treatment centre. Patients and investigators were not masked to treatment allocation. The co-primary endpoints were cognitive-deterioration-free survival and overall survival, and analyses were done by intention to treat. We report the final analysis. This trial is registered with ClinicalTrials.gov, number NCT01372774. FINDINGS: Between Nov 10, 2011, and Nov 16, 2015, 194 patients were enrolled and randomly assigned to SRS (98 patients) or WBRT (96 patients). Median follow-up was 11·1 months (IQR 5·1-18·0). Cognitive-deterioration-free survival was longer in patients assigned to SRS (median 3·7 months [95% CI 3·45-5·06], 93 events) than in patients assigned to WBRT (median 3·0 months [2·86-3·25], 93 events; hazard ratio [HR] 0·47 [95% CI 0·35-0·63]; p<0·0001), and cognitive deterioration at 6 months was less frequent in patients who received SRS than those who received WBRT (28 [52%] of 54 evaluable patients assigned to SRS vs 41 [85%] of 48 evaluable patients assigned to WBRT; difference -33·6% [95% CI -45·3 to -21·8], p<0·00031). Median overall survival was 12·2 months (95% CI 9·7-16·0, 69 deaths) for SRS and 11·6 months (9·9-18·0, 67 deaths) for WBRT (HR 1·07 [95% CI 0·76-1·50]; p=0·70). The most common grade 3 or 4 adverse events reported with a relative frequency greater than 4% were hearing impairment (three [3%] of 93 patients in the SRS group vs eight [9%] of 92 patients in the WBRT group) and cognitive disturbance (three [3%] vs five [5%]). There were no treatment-related deaths. INTERPRETATION: Decline in cognitive function was more frequent with WBRT than with SRS and there was no difference in overall survival between the treatment groups. After resection of a brain metastasis, SRS radiosurgery should be considered one of the standards of care as a less toxic alternative to WBRT for this patient population. FUNDING: National Cancer Institute.

Local control and toxicity outcomes in brainstem metastases treated with single fraction radiosurgery: is there a volume threshold for toxicity?

Gamma Knife Radiosurgery (GKRS) has been reported in the treatment of brainstem metastases while dose volume toxicity thresholds remain mostly undefined. A retrospective review of 52 brainstem metastases in 44 patients treated with GKRS was completed. A median dose of 18 Gy (range 10-22 Gy) was prescribed to the tumor margin (median 50 % isodose). 25 patients had undergone previous whole brain radiation therapy. Toxicity was graded by the LENT-SOMA scale. Mean and median follow-up was 10 and 6 months. Only 3 of the 44 patients are living. Multiple brain metastases were treated in 75 % of patients. Median size of lesions was 0.134 cc, (range 0.013-6.600 cc). Overall survival rate at 1 year was 32 % (95 % CI 51.0-20.1 %) with a median survival time of 6 months (95 % CI 5.0-16.5). Local control rate at 6 months and 1 year was 88 % (95 % CI 70-95 %) and 74 % (95 % CI 52-87 %). Cause of death was neurologic in 17 patients, non-neurologic in 20 patients, and unknown in four. Four patients experienced treatment related toxicities. Univariate analysis of tumor volume revealed that volume greater than 1.0 cc predicted for toxicity. A strategy of using lower marginal doses with GKRS to brain stem metastases appears to lead to a lower local control rate than seen with lesions treated within the standard dose range in other locations. Tumor size greater than 1.0 cc predicted for treatment-related toxicity.

Predicting the Effect of Proton Beam Therapy Technology on Pulmonary Toxicities for Patients With Locally Advanced Lung Cancer Enrolled in the Proton Collaborative Group Prospective Clinical Trial.

PURPOSE: This study aimed to predict the probability of grade ≥2 pneumonitis or dyspnea within 12 months of receiving conventionally fractionated or mildly hypofractionated proton beam therapy for locally advanced lung cancer using machine learning. METHODS AND MATERIALS: Demographic and treatment characteristics were analyzed for 965 consecutive patients treated for lung cancer with conventionally fractionated or mildly hypofractionated (2.2-3 Gy/fraction) proton beam therapy across 12 institutions. Three machine learning models (gradient boosting, additive tree, and logistic regression with lasso regularization) were implemented to predict Common Terminology Criteria for Adverse Events version 4 grade ≥2 pulmonary toxicities using double 10-fold cross-validation for parameter hyper-tuning without leak of information. Balanced accuracy and area under the curve were calculated, and 95% confidence intervals were obtained using bootstrap sampling. RESULTS: The median age of the patients was 70 years (range, 20-97), and they had predominantly stage IIIA or IIIB disease. They received a median dose of 60 Gy in 2 Gy/fraction, and 46.4% received concurrent chemotherapy. In total, 250 (25.9%) had grade ≥2 pulmonary toxicity. The probability of pulmonary toxicity was 0.08 for patients treated with pencil beam scanning and 0.34 for those treated with other techniques (P = 8.97e-13). Use of abdominal compression and breath hold were highly significant predictors of less toxicity (P = 2.88e-08). Higher total radiation delivered dose (P = .0182) and higher average dose to the ipsilateral lung (P = .0035) increased the likelihood of pulmonary toxicities. The gradient boosting model performed the best of the models tested, and when demographic and dosimetric features were combined, the area under the curve and balanced accuracy were 0.75 ± 0.02 and 0.67 ± 0.02, respectively. After analyzing performance versus the number of data points used for training, we observed that accuracy was limited by the number of observations. CONCLUSIONS: In the largest analysis of prospectively enrolled patients with lung cancer assessing pulmonary toxicities from proton therapy to date, advanced machine learning methods revealed that pencil beam scanning, abdominal compression, and lower normal lung doses can lead to significantly lower probability of developing grade ≥2 pneumonitis or dyspnea.

Validation of Patient-Reported Outcomes in Patients With Nonmetastatic Breast Cancer Receiving Comprehensive Nodal Irradiation in the RadComp Trial.

PURPOSE: Our purpose was to evaluate the measurement properties of patient-reported outcome (PRO) measures used in the ongoing RadComp pragmatic randomized clinical trial (PRCT). METHODS AND MATERIALS: The deidentified and blinded data set included 774 English-speaking female participants who completed their 6-month posttreatment assessment. Eleven PRO measures were evaluated, including the Trial Outcome Index from the Functional Assessment of Cancer Therapy-Breast (FACT-B), Satisfaction with Breast Cosmetic Outcomes, the BREAST-Q, and selected Patient-Reported Outcomes Measurement Information System (PROMIS) measures. PROs were measured at 3 timepoints: baseline, completion of radiation therapy (RT), and 6 months post-RT. Ten variables were used as validity anchors. Pearson or Spearman correlations were calculated between PROs and convergent validity indicators. Mean PRO differences between clinically distinct categories were compared with analysis of variance methods (known-groups validity). PRO change scores were mapped to change in other variables (sensitivity to change). RESULTS: Most correlations between PROs and validity indicators were large (≥0.5). Mean score for Satisfaction with Breast Cosmetic Outcomes was higher (better) for those with a lumpectomy compared with those with a mastectomy (P < .001). Mean scores for the FACT-B Trial Outcome Index and for PROMIS Fatigue and Ability to Participate in Social Roles and Activities were better for those with good baseline performance status compared with those with poorer baseline performance status (P < .05). At completion of RT and post-RT, mean scores for Satisfaction with Breast Cosmetic Outcomes and BREAST-Q Radiation were significantly different (P < .001) across categories for all Functional Assessment of Chronic Illness Therapy -Treatment Satisfaction - General items. There were medium-sized correlations between change scores for FACT-B Trial Outcome Index, Fatigue, Anxiety, and Ability to Participate in Social Roles and change scores in the Visual Analog Scale. CONCLUSIONS: For patients with nonmetastatic breast cancer receiving radiation in the RadComp PRCT, our findings demonstrate high reliability and validity for important PRO measures, supporting their psychometric strength and usefulness to reflect the effect of RT on health-related quality of life.

Association of circulating markers with cognitive decline after radiation therapy for brain metastasis.

BACKGROUND: A recent phase III trial (NCT01372774) comparing use of stereotactic radiosurgery [SRS] versus whole-brain radiation therapy [WBRT] after surgical resection of a single brain metastasis revealed that declines in cognitive function were more common with WBRT than with SRS. A secondary endpoint in that trial, and the primary objective in this secondary analysis, was to identify baseline biomarkers associated with cognitive impairment after either form of radiotherapy for brain metastasis. Here we report our findings on APOE genotype and serum levels of associated proteins and their association with radiation-induced neurocognitive decline. METHODS: In this retrospective analysis of prospectively collected samples from a completed randomized clinical trial, patients provided blood samples every 3 months that were tested by genotyping and enzyme-linked immunosorbent assay, and results were analyzed in association with cognitive impairment. RESULTS: The APOE genotype was not associated with neurocognitive impairment at 3 months. However, low serum levels of ApoJ, ApoE, or ApoA protein (all P < .01) and higher amyloid beta (Aß 1-42) levels (P = .048) at baseline indicated a greater likelihood of neurocognitive decline at 3 months after SRS, whereas lower ApoJ levels were associated with decline after WBRT (P = .014). CONCLUSIONS: Patients with these pretreatment serum markers should be counseled about radiation-related neurocognitive decline.

Breast cancer subtype affects patterns of failure of brain metastases after treatment with stereotactic radiosurgery.

We investigate the variance in patterns of failure after Gamma Knife™ radiosurgery (GKRS) for patients with brain metastases based on the subtype of the primary breast cancer. Between 2000 and 2010, 154 breast cancer patients were treated with GKRS for brain metastases. Tumor subtypes were approximated based on hormone receptor (HR) and HER2 status of the primary cancer: Luminal A/B (HR+/HER2(-)); HER2 (HER2+/HR(-)); Luminal HER2 (HR+/HER2+), Basal (HR(-)/HER2(-)), and then based on HER2 status alone. The median follow-up period was 54 months. Kaplan-Meier method was used to estimate survival times. Multivariable analysis was performed using Cox regression models. Median number of lesions treated was two (range 1-15) with a median dose of 20 Gy (range 9-24 Gy). Median overall survival (OS) was 7, 9, 11 and 22 months for Basal, Luminal A/B, HER2, and Luminal HER2, respectively (p = 0.001), and was 17 and 8 months for HER2+ and HER(-) patients, respectively (p < 0.001). Breast cancer subtype did not predict time to local failure (p = 0.554), but did predict distant brain failure rate (76, 47, 47, 36 % at 1 year for Basal, Luminal A/B, HER2, and Luminal HER2 respectively, p < 0.001). An increased proportion of HER2+ patients experienced neurologic death (46 vs 31 %, p = 0.066). Multivariate analysis revealed that HER2+ patients (p = 0.007) independently predicted for improved survival. Women with basal subtype have high rates of distant brain failure and worsened survival. Our data suggest that differences in biologic behavior of brain metastasis occur across breast cancer subtypes.

Smoking and Radiation-induced Skin Injury: Analysis of a Multiracial, Multiethnic Prospective Clinical Trial.

INTRODUCTION: Smoking during breast radiotherapy (RT) may be associated with radiation-induced skin injury (RISI). We aimed to determine if a urinary biomarker of tobacco smoke exposure is associated with increased rates of RISI during and after breast RT. PATIENTS AND METHODS: Women with Stage 0-IIIA breast cancer treated with breast-conserving surgery or mastectomy followed by RT to the breast or chest wall with or without regional nodal irradiation were prospectively enrolled on a multicenter study assessing acute/late RISI. 980 patients with urinary cotinine (UCot) measurements (baseline and end-RT) were categorized into three groups. Acute and late RISI was assessed using the ONS Acute Skin Reaction scale and the LENT-SOMA Criteria. RESULTS: Late Grade 2+ and Grade 3+ RISI occurred in 18.2% and 1.9% of patients, respectively-primarily fibrosis, pain, edema, and hyperpigmentation. Grade 2+ late RISI was associated with UCot group (P= 006). Multivariable analysis identified UCot-based light smoker/secondhand smoke exposure (HR 1.79, P= .10) and smoking (HR 1.60, p = .06) as non-significantly associated with an increased risk of late RISI. Hypofractionated breast RT was associated with decreased risk of late RISI (HR 0.51, P=.03). UCot was not associated with acute RISI, multivariable analysis identified race, obesity, RT site/fractionation, and bra size to be associated with acute RISI. CONCLUSIONS: Tobacco exposure during breast RT may be associated with an increased risk of late RISI without an effect on acute toxicity. Smoking cessation should be encouraged prior to radiotherapy to minimize these and other ill effects of smoking.

Association of Long-term Outcomes With Stereotactic Radiosurgery vs Whole-Brain Radiotherapy for Resected Brain Metastasis: A Secondary Analysis of The N107C/CEC.3 (Alliance for Clinical Trials in Oncology/Canadian Cancer Trials Group) Randomized Clinical Trial.

Importance: Long-term outcomes of radiotherapy are important in understanding the risks and benefits of therapies for patients with brain metastases. Objective: To determine how the use of postoperative whole-brain radiotherapy (WBRT) or stereotactic radiosurgery (SRS) is associated with quality of life (QOL), cognitive function, and intracranial tumor control in long-term survivors with 1 to 4 brain metastases. Design, Setting, and Participants: This secondary analysis of a randomized phase 3 clinical trial included 48 institutions in the US and Canada. Adult patients with 1 resected brain metastases but limited to those with 1 to 4 brain metastasis were eligible. Unresected metastases were treated with SRS. Long-term survivors were defined as evaluable patients who lived longer than 1 year from randomization. Patients were recruited between July 2011 and December 2015, and data were first analyzed in February 2017. For the present study, intracranial tumor control, cognitive deterioration, QOL, and cognitive outcomes were measured in evaluable patients who were alive at 12 months from randomization and reanalyzed in June 2017. Interventions: Stereotactic radiosurgery or WBRT. Main Outcomes and Measures: Intracranial tumor control, toxic effects, cognitive deterioration, and QOL. Results: Fifty-four patients (27 SRS arm, 27 WBRT arm; female to male ratio, 65% vs 35%) were included for analysis with a median follow-up of 23.8 months. Cognitive deterioration was less frequent with SRS (37%-60%) compared with WBRT (75%-91%) at all time points. More patients declined by 2 or more standard deviations (SDs) in 1 or more cognitive tests for WBRT compared with SRS at 3, 6, and 9 months (70% vs 22%, 46% vs 19%, and 50% vs 20%, respectively). A 2 SD decline in at least 2 cognitive tests was associated with worse 12-month QOL in emotional well-being, functional well-being, general, additional concerns, and total scores. Overall QOL and functional independence favored SRS alone for categorical change at all time points. Total intracranial control for SRS alone vs WBRT at 12 months was 40.7% vs 81.5% (difference, -40.7; 95% CI, -68.1% to -13.4%), respectively. Data were first analyzed in February 2017. Conclusions and Relevance: The use of SRS alone compared with WBRT resulted in less cognitive deterioration among long-term survivors. The association of late cognitive deterioration with WBRT was clinically meaningful. A significant decline in cognition (2 SD) was associated with overall QOL. However, intracranial tumor control was improved with WBRT. This study provides detailed insight into cognitive function over time in this patient population. Trial Registration: ClinicalTrials.gov Identifier: NCT01372774; ALLIANCE/CCTG: N107C/CEC.3 (Alliance for Clinical Trials in Oncology/Canadian Cancer Trials Group).

Proton Therapy for Breast Cancer: A Consensus Statement From the Particle Therapy Cooperative Group Breast Cancer Subcommittee.

Radiation therapy plays an important role in the multidisciplinary management of breast cancer. Recent years have seen improvements in breast cancer survival and a greater appreciation of potential long-term morbidity associated with the dose and volume of irradiated organs. Proton therapy reduces the dose to nontarget structures while optimizing target coverage. However, there remain additional financial costs associated with proton therapy, despite reductions over time, and studies have yet to demonstrate that protons improve upon the treatment outcomes achieved with photon radiation therapy. There remains considerable heterogeneity in proton patient selection and techniques, and the rapid technological advances in the field have the potential to affect evidence evaluation, given the long latency period for breast cancer radiation therapy recurrence and late effects. In this consensus statement, we assess the data available to the radiation oncology community of proton therapy for breast cancer, provide expert consensus recommendations on indications and technique, and highlight ongoing trials' cost-effectiveness analyses and key areas for future research.

Optimizing Whole Brain Radiation Therapy Dose and Fractionation: Results From a Prospective Phase 3 Trial (NCCTG N107C [Alliance]/CEC.3).

PURPOSE: Whole brain radiation therapy (WBRT) remains a commonly used cancer treatment, although controversy exists regarding the optimal dose/fractionation to optimize intracranial tumor control and minimize resultant cognitive deficits. METHODS AND MATERIALS: NCCTG N107C [Alliance]/CEC.3 randomized 194 patients with brain metastases to either stereotactic radiosurgery alone or WBRT after surgical resection. Among the 92 patients receiving WBRT, sites predetermined the dose/fractionation that would be used for all patients treated at that site (either 30 Gy in 10 fractions or 37.5 Gy in 15 fractions). Analyses were performed using Kaplan-Meier estimates, log rank tests, and Fisher's exact tests. RESULTS: Among 92 patients treated with surgical resection and adjuvant WBRT, 49 were treated with 30 Gy in 10 fractions (53%), and 43 were treated with 37.5 Gy in 15 fractions (47%). Baseline characteristics, including cognitive testing, were well balanced between groups with the exception of primary tumor type (lung cancer histology was more frequent with protracted WBRT: 72% vs 45%, P = .01), and 93% of patients completed the full course of WBRT. A more protracted WBRT dose regimen (37.5 Gy in 15 fractions) did not significantly affect time to cognitive failure (hazard ratio [HR], 0.9; 95% confidence interval [CI], 0.6-1.39; P = .66), surgical bed control (HR, 0.52 [95% CI, 0.22-1.25], P = .14), intracranial tumor control (HR, 0.56 [95% CI, 0.28-1.12], P = .09), or overall survival (HR, 0.72 [95% CI, 0.45-1.16], P = .18). Although there was no reported radionecrosis, there is a statistically significant increase in the risk of at least 1 grade ≥3 adverse event with 37.5 Gy in 15 fractions versus 30 Gy in 10 fractions (54% vs 31%, respectively, P = .03). CONCLUSIONS: This post hoc analysis does not demonstrate that protracted WBRT courses reduce the risk of cognitive deficit, improve tumor control in the hypoxic surgical cavity, or otherwise improve the therapeutic ratio. Adverse events were significantly higher with the lengthened course of WBRT. For patients with brain metastases where WBRT is recommended, shorter course hypofractionated regimens remain the current standard of care.

Is the Importance of Heart Dose Overstated in the Treatment of Non-Small Cell Lung Cancer? A Systematic Review of the Literature.

PURPOSE: Some recent studies have suggested a relationship between cardiac dose and mortality in non-small cell lung cancer (NSCLC), but others have reported conflicting data. The goal of this study was to conduct a systematic review and meta-analysis to provide an evidence-based estimate of the relationship between cardiac dose and mortality in these patients. METHODS AND MATERIALS: A systematic review of MEDLINE (PubMed) and Embase databases (inception to January 2018) was performed according to PRISMA guidelines. Studies that evaluated cardiac dosimetric factors in patients with NSCLC and included outcomes of cardiac events, cardiac mortality, and/or overall survival were identified. RESULTS: From 5614 patients across 22 studies, a total of 214 cardiac dosimetric parameters (94 unique) were assessed as possible predictors of cardiac toxicity or death. Assessed predictors included general (eg, mean heart dose [MHD]), threshold-based (eg, heart V5), and anatomic-based (eg, atria, ventricles) dosimetric factors. The most commonly analyzed parameters were MHD, heart V5, and V30. Most studies did not make corrections for multiplicity of testing. For overall survival, V5 was found to be significant on multivariable analysis (MVA) in 1 of 11 studies and V30 in 2 of 12 studies; MHD was not significant in any of 8 studies. For cardiac events, V5 was found to be significant on multivariable analysis in 1 of 2 studies, V30 in 1 of 3 studies, and MHD in 2 of 4 studies. A meta-analysis of the data could not be performed because most negative studies did not report effect estimates. CONCLUSIONS: Consistent heart dose-volume parameters associated with overall survival of patients with NSCLC were not identified. Multiplicity of testing is a major issue and likely inflates the overall risk of type I errors in the literature. Future studies should specify predictors a priori, correct for multiplicity of testing, and report effect estimates for nonsignificant variables.

Safety and Efficacy of a Five-Fraction Stereotactic Body Radiotherapy Schedule for Centrally Located Non-Small-Cell Lung Cancer: NRG Oncology/RTOG 0813 Trial.

PURPOSE: Patients with centrally located early-stage non-small-cell lung cancer (NSCLC) are at a higher risk of toxicity from high-dose ablative radiotherapy. NRG Oncology/RTOG 0813 was a phase I/II study designed to determine the maximum tolerated dose (MTD), efficacy, and toxicity of stereotactic body radiotherapy (SBRT) for centrally located NSCLC. MATERIALS AND METHODS: Medically inoperable patients with biopsy-proven, positron emission tomography-staged T1 to 2 (≤ 5 cm) N0M0 centrally located NSCLC were accrued into a dose-escalating, five-fraction SBRT schedule that ranged from 10 to 12 Gy/fraction (fx) delivered over 1.5 to 2 weeks. Dose-limiting toxicity (DLT) was defined as any treatment-related grade 3 or worse predefined toxicity that occurred within the first year. MTD was defined as the SBRT dose at which the probability of DLT was closest to 20% without exceeding it. RESULTS: One hundred twenty patients were accrued between February 2009 and September 2013. Patients were elderly, there were slightly more females, and the majority had a performance status of 0 to 1. Most cancers were T1 (65%) and squamous cell (45%). Organs closest to planning target volume/most at risk were the main bronchus and large vessels. Median follow-up was 37.9 months. Five patients experienced DLTs; MTD was 12.0 Gy/fx, which had a probability of a DLT of 7.2% (95% CI, 2.8% to 14.5%). Two-year rates for the 71 evaluable patients in the 11.5 and 12.0 Gy/fx cohorts were local control, 89.4% (90% CI, 81.6% to 97.4%) and 87.9% (90% CI, 78.8% to 97.0%); overall survival, 67.9% (95% CI, 50.4% to 80.3%) and 72.7% (95% CI, 54.1% to 84.8%); and progression-free survival, 52.2% (95% CI, 35.3% to 66.6%) and 54.5% (95% CI, 36.3% to 69.6%), respectively. CONCLUSION: The MTD for this study was 12.0 Gy/fx; it was associated with 7.2% DLTs and high rates of tumor control. Outcomes in this medically inoperable group of mostly elderly patients with comorbidities were comparable with that of patients with peripheral early-stage tumors.

Long-term Follow-up on NRG Oncology RTOG 0915 (NCCTG N0927): A Randomized Phase 2 Study Comparing 2 Stereotactic Body Radiation Therapy Schedules for Medically Inoperable Patients With Stage I Peripheral Non-Small Cell Lung Cancer.

PURPOSE: To present long-term results of RTOG 0915/NCCTG N0927, a randomized lung stereotactic body radiation therapy trial of 34 Gy in 1 fraction versus 48 Gy in 4 fractions. METHODS AND MATERIALS: This was a phase 2 multicenter study of patients with medically inoperable non-small cell lung cancer with biopsy-proven peripheral T1 or T2 N0M0 tumors, with 1-year toxicity rates as the primary endpoint and selected failure and survival outcomes as secondary endpoints. The study opened in September 2009 and closed in March 2011. Final data were analyzed through May 17, 2018. RESULTS: Eighty-four of 94 patients accrued were eligible for analysis: 39 in arm 1 and 45 in arm 2. Median follow-up time was 4.0 years for all patients and 6.0 years for those alive at analysis. Rates of grade 3 and higher toxicity were 2.6% in arm 1 and 11.1% in arm 2. Median survival times (in years) for 34 Gy and 48 Gy were 4.1 versus 4.6, respectively. Five-year outcomes (95% confidence interval) for 34 Gy and 48 Gy were a primary tumor failure rate of 10.6% (3.3%-23.1%) versus 6.8% (1.7%-16.9%); overall survival of 29.6% (16.2%-44.4%) versus 41.1% (26.6%-55.1%); and progression-free survival of 19.1% (8.5%-33.0%) versus 33.3% (20.2%-47.0%). Distant failure as the sole failure or a component of first failure occurred in 6 patients (37.5%) in the 34 Gy arm and in 7 (41.2%) in the 48 Gy arm. CONCLUSIONS: No excess in late-appearing toxicity was seen in either arm. Primary tumor control rates at 5 years were similar by arm. A median survival time of 4 years for each arm suggests similar efficacy, pending any larger studies appropriately powered to detect survival differences.

Radiation safety issues with positron-emission/computed tomography simulation for stereotactic body radiation therapy.

Stereotactic body radiation therapy (SBRT) simulations using a Stereotactic Body Frame (SBF: Elekta, Stockholm, Sweden) were expanded to include 18F-deoxyglucosone positron-emission tomography (FDG PET) for treatment planning. Because of the length of time that staff members are in close proximity to the patient, concerns arose over the radiation safety issues associated with these simulations. The present study examines the radiation exposures of the staff performing SBRT simulations, and provides some guidance on limiting staff exposure during these simulations. Fifteen patients were simulated with PET/CT using the SBF. Patients were immobilized in the SBF before the FDG was administered. The patients were removed from the frame, injected with FDG, and allowed to uptake for approximately 45 minutes. After uptake, the patients were repositioned in the SBF. During the repositioning, exposure rates were recorded at the patient's surface, at the SBF surface, and at 15 cm, 30 cm, and 1 m from the SBF. Administered dose and the approximate time spent on patient repositioning were also recorded. The estimated dose to staff was compared with the dose to staff performing conventional diagnostic PET studies. The average length of time spent in close proximity (<50 cm) to the patient after injection was 11.7 minutes, or more than twice the length of time reported for diagnostic PET staff. That time yielded an estimated average dose to the staff of 26.5 microSv per simulation. The annual occupational exposure limit is 50 mSv. Based on dose per simulation, staff would have to perform nearly 1900 SBRT simulations annually to exceed the occupational limit. Therefore, at the current rate of 50-100 simulations annually, the addition of PET studies to SBRT simulations is safe for our staff. However, ALARA ("as low as reasonably achievable") principles still require some radiation safety considerations during SBRT simulations. The PET/CT-based SBRT simulations are safe and important for treatment planning that optimizes biologic dose distribution with highly accurate and reproducible target definition.

Stereotactic Body Radiation Therapy Versus Surgery for Early Lung Cancer Among US Veterans.

BACKGROUND: Stereotactic body radiation therapy (SBRT) has been proposed as a potential alternative to surgery for early lung cancer, although we lack well-powered prospective randomized data comparing these treatments, and existing studies suffer from incomplete information on confounders that can bias results. Here, we evaluated the comparative effectiveness of surgery and SBRT in lung cancer treatment using a large extensively detailed database from the Veteran's Affairs system. METHODS: We identified veterans with biopsy-proven clinical stage I non-small cell lung cancer diagnosed between 2006 and 2015 from within the Veteran's Affairs Informatics and Computing Infrastructure. We compared cancer-specific survival among patients receiving lobectomy, sublobar resection, or SBRT using univariable and multivariable competing risk analyses. Multivariable analyses adjusted for confounders including preoperative pulmonary function, smoking status, comorbidity, and staging workup procedures. RESULTS: In all, 4,069 patients were included (449 SBRT, 2,986 lobectomy, 634 sublobar resection). Unadjusted analysis found higher immediate postprocedural mortality in the surgery groups compared with the SBRT group. The multivariable analysis considering long-term survival found higher cancer-specific mortality for SBRT compared with lobectomy (subdistribution hazard ratio 1.45, 95% confidence interval: 1.09 to 1.94, p = 0.01), although no survival difference between SBRT and sublobar resection (subdistribution hazard ratio 1.25, 95% confidence interval: 0.93 to 1.68, p = 0.15). CONCLUSIONS: Among a large cohort of early stage lung cancer patients, we found that lobectomy had improved survival compared with SBRT, although we found no survival difference between sublobar resection and SBRT. Despite these findings, the potential for unmeasured confounding remains and prospective randomized trials are needed to better compare these treatment modalities.

Phase 1 Study of Accelerated Hypofractionated Radiation Therapy With Concurrent Chemotherapy for Stage III Non-Small Cell Lung Cancer: CALGB 31102 (Alliance).

PURPOSE: To investigate the safety of accelerated hypofractionated radiation therapy (AHRT) with concurrent chemotherapy (CT) for inoperable stage III non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: The primary objectives were to define the maximally tolerable course of accelerated radiation therapy and to describe toxicities of therapy. Total radiation therapy remained at 60 Gy. The number of once-daily fractions in each successive cohort was reduced as follows: cohort 1, 60 Gy in 27 fractions; cohort 2, 60 Gy in 24 fractions; cohort 3, 60 Gy in 22 fractions; and cohort 4, 60 Gy in 20 fractions. Concurrent treatment consisted of weekly carboplatin area under the curve (AUC) 2 and paclitaxel 45 mg/m2. Consolidation treatment consisted of carboplatin AUC 6 and paclitaxel 200 mg/m2 every weeks × 2 cycles. Maximum tolerated dose: Of 6 patients/cohort, ≤2 patients experienced grade ≥3 toxicity, and ≤1 patient experienced grade ≥4 toxicity. RESULTS: 22 patients were accrued; of those, 21 patients were evaluable between July 2012 and May 2014. Grade 5 toxicity occurred in 3 patients: 1 patient in cohort 2 (hemoptysis), 2 patients in cohort 3 (hemoptysis, pneumonitis). The maximum tolerated dose (MTD) was defined by cohort 2 (60 Gy in 2.5 Gy/fraction). Time to grade 5 toxicity was 9 months, 6 months, and 9 months after the start of treatment. The median follow-up time was 23.0 months (range, 7.6-30.6 months) in living patients, the median overall survival was 19.3 months (95% confidence interval [CI] 9.3-34.0 months), and the median progression-free survival was 12.2 months (95% CI 6.1-22.5 months). CONCLUSIONS: Only modest hypofractionation was achievable as a result of long-term toxicities. Nevertheless, the MTD of 60 Gy given at 2.5 Gy/fraction allows completion of RT in 20% fewer treatments than conventional therapy. Further investigation of AHRT may help to better define the therapeutic index.

Long-Term Outcomes of a Phase 2 Trial of Chemotherapy With Consolidative Radiation Therapy for Oligometastatic Non-Small Cell Lung Cancer.

PURPOSE: Recent data indicate consolidative radiation therapy improves progression-free survival (PFS) for patients with oligometastatic non-small cell lung cancer (NSCLC). Data on long-term outcomes are limited. METHODS AND MATERIALS: This prospective, multicenter, single-arm, phase 2 trial was initiated in 2010 and enrolled patients with oligometastatic NSCLC. Oligometastatic disease was defined as a maximum of 5 metastatic lesions for all disease sites, including no more than 3 active extracranial metastatic lesions. Limited mediastinal lymph node involvement was allowed. Patients achieving a partial response or stable disease after 3 to 6 cycles of platinum-based chemotherapy were treated with CRT to the primary and metastatic sites of disease, followed by observation alone. The primary endpoint was PFS, with secondary endpoints of local control, overall survival (OS), and safety. RESULTS: Twenty-nine patients were enrolled between October 2010 and October 2015, and 27 were eligible for consolidative radiation therapy. The study was closed early because of slow accrual but met its primary endpoint for success, which was PFS >6 months (P < .0001). The median PFS (95% confidence interval) was 11.2 months (7.6-15.9 months), and the median OS was 28.4 months (14.5-45.8 months). Survival outcomes were not significantly different for patients with brain metastases (P = .87 for PFS; P = .12 for OS) or lymph node involvement (P = .74 for PFS; P = .86 for OS). CONCLUSIONS: For patients with oligometastatic NSCLC, chemotherapy followed by consolidative radiation therapy without maintenance chemotherapy was associated with encouraging long-term outcomes.

Classification for long-term survival in oligometastatic patients treated with ablative radiotherapy: A multi-institutional pooled analysis.

BACKGROUND: Radiotherapy is increasingly used to treat oligometastatic patients. We sought to identify prognostic criteria in oligometastatic patients undergoing definitive hypofractionated image-guided radiotherapy (HIGRT). METHODS: Exclusively extracranial oligometastatic patients treated with HIGRT were pooled. Characteristics including age, sex, primary tumor type, interval to metastatic diagnosis, number of treated metastases and organs, metastatic site, prior systemic therapy for primary tumor treatment, prior definitive metastasis-directed therapy, and systemic therapy for metastasis associated with overall survival (OS), progression-free survival (PFS), and treated metastasis control (TMC) were assessed by the Cox proportional hazards method. Recursive partitioning analysis (RPA) identified prognostic risk strata for OS and PFS based on pretreatment factors. RESULTS: 361 patients were included. Primary tumors included non-small cell lung (17%), colorectal (19%), and breast cancer (16%). Three-year OS was 56%, PFS was 24%, and TMC was 72%. On multivariate analysis, primary tumor, interval to metastases, treated metastases number, and mediastinal/hilar lymph node, liver, or adrenal metastases were associated with OS. Primary tumor site, involved organ number, liver metastasis, and prior primary disease chemotherapy were associated with PFS. OS RPA identified five classes: class 1: all breast, kidney, or prostate cancer patients (BKP) (3-year OS 75%, 95% CI 66-85%); class 2: patients without BKP with disease-free interval of 75+ months (3-year OS 85%, 95% CI 67-100%); class 3: patients without BKP, shorter disease-free interval, ≤ two metastases, and age < 62 (3-year OS 55%, 95% CI 48-64%); class 4: patients without BKP, shorter disease-free interval, ≥ three metastases, and age < 62 (3-year OS 38%, 95% CI 24-60%); class 5: all others (3-year OS 13%, 95% CI 5-35%). Higher biologically effective dose (BED) (p < 0.01) was associated with OS. CONCLUSIONS: We identified clinical factors defining oligometastatic patients with favorable outcomes, who we hypothesize are most likely to benefit from metastasis-directed therapy.