Frontiers in the Application of RF Vacuum Electronics.

The application of radio frequency (RF) vacuum electronics for the betterment of the human condition began soon after the invention of the first vacuum tubes in the 1920s and has not stopped since. Today, microwave vacuum devices are powering important applications in health treatment, material and biological science, wireless communication-terrestrial and space, Earth environment remote sensing, and the promise of safe, reliable, and inexhaustible energy. This article highlights some of the exciting application frontiers of vacuum electronics.

Use and outcomes of dual antiplatelet therapy for acute coronary syndrome in patients with chronic kidney disease: insights from the Canadian Observational Antiplatelet Study (COAPT).

Chronic kidney disease (CKD) increases the risk of adverse outcomes in acute coronary syndrome (ACS). The optimal regimen of dual antiplatelet therapy (DAPT) post-percutaneous coronary intervention (PCI) in CKD poses a challenge due to the increased bleeding and clotting tendencies, particularly since patients with CKD were underrepresented in randomized controlled trials. We examined the practice patterns of DAPT prescription stratified by the presence of CKD. The multicentre prospective Canadian Observational Antiplatelet Study (COAPT) enrolled patients with ACS between December 2011 and May 2013. The present study is a subgroup analysis comparing type and duration of DAPT and associated outcomes among patients with and without CKD (eGFR < 60 ml/min/1.73 m2, calculated by CKD-EPI). Patients with CKD (275/1921, 14.3%) were prescribed prasugrel/ticagrelor less (18.5% vs 25.8%, p = 0.01) and had a shorter duration of DAPT therapy versus patients without CKD (median 382 vs 402 days, p = 0.003). CKD was associated with major adverse cardiovascular events (MACE) at 12 months (p < 0.001) but not bleeding when compared to patients without CKD. CKD was associated with MACE in both patients on prasugrel/ticagrelor (p = 0.017) and those on clopidogrel (p < 0.001) (p for heterogeneity = 0.70). CKD was associated with increased bleeding only among patients receiving prasugrel/ticagrelor (p = 0.007), but not among those receiving clopidogrel (p = 0.64) (p for heterogeneity = 0.036). Patients with CKD had a shorter DAPT duration and were less frequently prescribed potent P2Y12 inhibitors than patients without CKD. Overall, compared with patients without CKD, patients with CKD had higher rates of MACE and similar bleeding rates. However, among those prescribed more potent P2Y12 inhibitors, CKD was associated with more bleeding than those without CKD. Further studies are needed to better define the benefit/risk evaluation, and establish a more tailored and evidence-based DAPT regimen for this high-risk patient group.

Elective Nodal Irradiation for Limited-stage Small-cell Lung Cancer: Survey of US Radiation Oncologists on Practice Patterns.

BACKGROUND: Traditionally, elective nodal irradiation (ENI) has been used in clinical trials that have established thoracic radiotherapy as instrumental in improving survival for patients with limited-stage small-cell lung cancer (LS-SCLC). However, several reports have suggested that the omission of ENI might be appropriate. Current US practice patterns are unknown regarding ENI for patients with LS-SCLC. MATERIALS AND METHODS: We surveyed US radiation oncologists via an institutional review board-approved questionnaire. The questions covered demographics, treatment recommendations, and self-assessed knowledge of key clinical trials. χ2 and Cochran-Armitage tests were used to evaluate for statistically significant correlations between responses. RESULTS: We received 309 responses. Of the respondents, 21% recommended ENI for N0 LS-SCLC, 29% for N1, and 30% for N2; 64% did not recommend ENI for any of these clinical scenarios. The respondents who recommended ENI were more likely to have been practicing for > 10 years (P < .001), more likely to be in private practice (P = .04), and less likely to be familiar with the ongoing Cancer and Leukemia Group B 30610 trial (P = .04). Almost all respondents (93%) prescribed the same radiation dose to the primary disease and involved lymph nodes. When delivering ENI, 36% prescribed the same dose to the involved and elective nodes, and 64% prescribed a lower dose to the elective nodes. CONCLUSION: Nearly two thirds of respondents did not recommend ENI, which represents a shift in practice. A recent large clinical trial that omitted ENI reported greater overall survival than previously reported and lower-than-expected radiation toxicities, lending further evidence that omitting ENI should be considered a standard treatment strategy.

Radiation Dose and Fractionation for Limited-stage Small-cell Lung Cancer: Survey of US Radiation Oncologists on Practice Patterns.

BACKGROUND: Thoracic radiotherapy (TRT) with concurrent chemotherapy is standard for limited-stage small-cell lung cancer (LS-SCLC). However, the optimal dosing and fractionation remain unclear. The National Comprehensive Cancer Network guidelines have recommended either 45 Gy delivered twice daily (BID) or 60 to 70 Gy delivered once daily (QD). However, the current practice patterns among US radiation oncologists are unknown. MATERIALS AND METHODS: We surveyed US radiation oncologists using an institutional review board-approved questionnaire. The questions covered demographic data, self-rated knowledge of key trials, and treatment recommendations. RESULTS: We received 309 responses from radiation oncologists. Of the 309 radiation oncologists, 60% preferred TRT QD and 76% acknowledged QD to be more common in their practice. The respondents in academic settings were more likely to endorse BID treatment by both preference (P = .001) and actual practice (P = .009). The concordance between preferring QD and administering QD in practice was 100%. In contrast, 40% of respondents who preferred BID actually administered QD more often. Also, 15% of physicians would be unwilling to switch from QD to BID and 3% would be unwilling to switch from BID to QD, even on patient request. Most respondents (88%) recommended a dose of 45 Gy for BID treatment. For QD treatment, the division was greater, with 54% recommending 60 Gy, 30% recommending 63 to 66 Gy, and 10% recommending 70 Gy. CONCLUSION: Substantial variation exists in how US radiation oncologists approach TRT dosing and fractionation for LS-SCLC. Three quarters of our respondents reported administering TRT QD most often. The most common doses were 60 Gy QD and 45 Gy BID. The results of the present survey have provided the most up-to-date information on US practice patterns for LS-SCLC.

Timing of Thoracic Radiation Therapy With Chemotherapy in Limited-stage Small-cell Lung Cancer: Survey of US Radiation Oncologists on Current Practice Patterns.

INTRODUCTION: For limited-stage small-cell lung cancer (LS-SCLC), National Comprehensive Cancer Network guidelines recommend that thoracic radiotherapy (TRT) be delivered concurrently with chemotherapy and early in the regimen, with cycle 1 or 2. Evidence is conflicting regarding the benefit of early timing of TRT. A Korean randomized trial did not see a survival difference between early (cycle 1) and late (cycle 3) TRT. Current United States (US) practice patterns are unknown. MATERIALS AND METHODS: We surveyed US radiation oncologists using an institutional review board-approved online questionnaire. Questions covered treatment recommendations, self-rated knowledge of trials, and demographics. RESULTS: We received 309 responses from radiation oncologists. Ninety-eight percent recommend concurrent chemoradiotherapy over sequential. Seventy-one percent recommend starting TRT in cycle 1 of chemotherapy, and 25% recommend starting in cycle 2. In actual practice, TRT is started most commonly in cycle 2 (48%) and cycle 1 (44%). One-half of respondents (54%) believe starting in cycle 1 improves survival compared with starting in cycle 3. Knowledge of the Korean trial was associated with flexibility in delaying TRT to cycle 2 or 3 (P = .02). Over one-third (38%) treat based on pre-chemotherapy volume. CONCLUSION: US radiation oncologists strongly align with National Comprehensive Cancer Network guidelines, which recommend early concurrent chemoradiotherapy. Nearly three-quarters of respondents prefer starting TRT with cycle 1 of chemotherapy. However, knowledge of a trial supporting a later start was associated with flexibility in delaying TRT. Treating based on pre-chemotherapy volume-endorsed by over one-third of respondents-may add unnecessary toxicity. This survey can inform development of future trials.

Prophylactic Cranial Irradiation for Limited-Stage Small-Cell Lung Cancer: Survey of US Radiation Oncologists on Current Practice Patterns.

PURPOSE: Prophylactic cranial irradiation (PCI) in patients with limited-stage small-cell lung cancer (LS-SCLC) is considered the standard of care. Meta-analysis of 7 clinical trials indicates a survival benefit to PCI, but all of these trials were conducted in the pre-magnetic resonance imaging (MRI) era. Therefore, routine brain imaging with MRI before PCI-as recommended by National Comprehensive Cancer Network guidelines-is not directly supported by the evidence. Current US practice patterns for patients with LS-SCLC are unknown. MATERIALS AND METHODS: We surveyed practicing US radiation oncologists via an institutional review board-approved online questionnaire. Questions covered demographic information and treatment recommendations for LS-SCLC. RESULTS: We received 309 responses from US radiation oncologists. Ninety-eight percent recommended PCI for patients with LS-SCLC, 96% obtained brain MRI before PCI, 33% obtained serial brain imaging with MRI after PCI to detect new metastases, and 35% recommended memantine for patients undergoing PCI. Recommending memantine was associated with fewer years of practice (P < .001), fewer lung cancer patients treated per year (P = .045), and fewer LS-SCLC patients treated per year (P = .024). CONCLUSION: Almost all responding radiation oncologists recommended PCI and pre-PCI brain MRI for LS-SCLC patients with disease responsive to initial therapy. Only a third of respondents followed these patients with serial brain MRI. Approximately one third provided memantine therapy to try to limit neurocognitive effects of PCI. Further research is warranted to determine the best treatment for patients with LS-SCLC. This survey can inform the development of future trials that depend on participation from radiation oncologists.

Baseline characteristics, adenosine diphosphate receptor inhibitor treatment patterns, and in-hospital outcomes of myocardial infarction patients undergoing percutaneous coronary intervention in the prospective Canadian Observational AntiPlatelet sTudy (COAPT).

BACKGROUND: Contemporary use of dual antiplatelet therapy and consistency with guideline recommendations in acute coronary syndrome patients undergoing percutaneous coronary intervention (PCI) have not been well characterized. METHODS: The COAPT was a prospective, observational, multicenter, longitudinal study of patients with myocardial infarction (MI) undergoing PCI. Baseline characteristics, treatment patterns, processes of care, factors associated with switching to and from novel adenosine diphosphate receptor inhibitors (ADPris), and in-hospital outcomes are described. RESULTS: Among 2,179 MI patients undergoing PCI during their index hospitalization, 1,328 (60.9%) had ST elevation. Initial ADPri use included clopidogrel in 1,812 (83.2%), prasugrel in 125 (5.7%), and ticagrelor in 242 (11.1%). At discharge, 1,597 patients (73.4%) were prescribed clopidogrel, 220 (10.1%) prasugrel, and 358 (16.5%) ticagrelor. Switching between ADPri therapies during the index hospitalization occurred in 15.3%, 22.4%, and 25.2% of patients initially started on clopidogrel, prasugrel, and ticagrelor, respectively. Most switches over the 15-month study period occurred during the index admission (16.8% of patients vs 4.4% switches postdischarge). Major adverse cardiovascular events occurred in 7.5% of patients during the index hospitalization. In-hospital bleeding events occurred in 6.0% of patients and most were mild. CONCLUSIONS: Despite randomized trial evidence and guideline recommendations, only a minority of Canadian MI patients undergoing PCI initially received or were discharged on one of the newer ADPri agents. These findings suggest an opportunity to improve upon the appropriate selection of the ADPris at index hospitalization and discharge in Canadian MI patients undergoing PCI.

Ischemic and bleeding events in patients with myocardial infarction undergoing percutaneous coronary intervention who require oral anticoagulation: Insights from the Canadian observational AntiPlatelet sTudy.

BACKGROUND: Since the introduction of newer, more potent P2Y12 receptor inhibitors (P2Y12ris), practice patterns and associated clinical outcomes in patients with myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI) and also requiring oral anticoagulation (OAC) have not been fully characterized. METHODS: The Canadian Observational Antiplatelet Study was a prospective, multicenter, longitudinal, observational study (26 hospitals, December 2011 to May 2013) describing P2Y12ri treatment patterns and outcomes in patients with ST-elevation and non-ST-elevation MI undergoing PCI. We describe the clinical characteristics, treatment patterns, bleeding, and ischemic outcomes over the 15-month follow-up within and between the subgroups of patients discharged on either dual-antiplatelet therapy (DAPT) (acetyl salicylic acid [ASA]+P2Y12ri) or triple therapy (ASA+P2Y12ri+OAC). RESULTS: Of the 2,034 patients at discharge, 86% (n = 1,757) were on DAPT, whereas 14% (n = 277) were on triple therapy (50% warfarin, 50% non-vitamin K OAC [NOAC]). The frequency of newer P2Y12ri use (prasugrel or ticagrelor) was similar in the DAPT and triple therapy groups (28% vs 26%, respectively). In the triple therapy group, NOAC use was higher in those receiving a new P2Y12ri compared to those receiving clopidogrel (75% vs 41%, respectively, P < .0001). The unadjusted and adjusted events of major cardiovascular event (MACE) and bleeding were higher in the triple therapy group. For patients on triple therapy, the bleeding or MACE events were not significantly different between those on clopidogrel versus those on ticagrelor or prasugrel. CONCLUSION: In this observational study of MI patients requiring PCI, 1 in 8 were discharged on triple antithrombotic therapy, of whom 26% were on newer P2Y12ris. Patients on triple therapy had higher risk at baseline, with higher unadjusted and adjusted MACE and bleeding events compared to those on DAPT alone. Among triple therapy-treated patients, there was no difference in the MACE and bleeding events regardless of the P2Y12ri used.

Current Patterns of Care for Patients with Extensive-Stage SCLC: Survey of U.S. Radiation Oncologists on Their Recommendations Regarding Prophylactic Cranial Irradiation.

INTRODUCTION: Conflicting data from randomized clinical trials incite the debate over the appropriate use of prophylactic cranial irradiation (PCI) for patients with extensive-stage SCLC (ES-SCLC) who achieve clinical response to systemic chemotherapy. The current pattern of practice among U.S. radiation oncologists is unknown. METHODS: We surveyed practicing U.S. radiation oncologists through a short online questionnaire. Respondents' characteristics and their self-rated knowledge base were analyzed for association with their treatment recommendations. RESULTS: We received 473 responses from practicing U.S. radiation oncologists. More than half of the respondents had been practicing for more than 10 years after completing residency training, and 70% had treated more than 10 patients with lung cancer per year. Of the respondents, 90% recommended brain magnetic resonance imaging (MRI) before initiation of PCI and 98% recommended PCI for patients with ES-SCLC after systemic chemotherapy. Half of the respondents followed their patients with brain MRI after completion of PCI. One-third of the respondents prescribed memantine to patients undergoing PCI. Among the respondents, recent graduates (p = 0.004) and physicians practicing in academic centers (p = 0.005) were more likely to prescribe memantine. Self-rated knowledge base was not associated with any treatment recommendations. CONCLUSIONS: Our analysis revealed that among the respondents, there was a very high adherence to current National Comprehensive Cancer Network guidelines, which recommend providing universal PCI and obtaining brain MRI before initiation of PCI for patients with ES-SCLC with clinical response to systemic chemotherapy. These guidelines and practice patterns are not supported by clinical evidence because patients in the European Organization for Research and Treatment of Cancer trial did not undergo brain MRI before PCI and the Japanese randomized trial has shown a possible detrimental effect of PCI on overall survival when brain MRI was incorporated. A critical reevaluation of current guidelines is essential to determine the appropriate management of these patients.

Does Graded Prognostic Assessment outperform Recursive Partitioning Analysis in patients with moderate prognosis brain metastases?

AIM: To compare the clinical utility of the Recursive Partitioning Analysis (RPA) and Graded Prognostic Assessment (GPA) in predicting outcomes for moderate prognosis patients with brain metastases. METHODS & MATERIALS: We reviewed 101 whole brain radiotherapy cases. RPA and GPA were calculated. Overall survival was compared. RESULTS: Sixty-eight patients had moderate prognosis. RPA patient characteristics for increased death hazard were ≤10 WBRT fractions or no surgery/radiosurgery. GPA patients had increased death risk with no surgery/radiosurgery or lower Karnofsky Performance Status. CONCLUSION: The indices have similar predicted survival. Patients scored by RPA with longer radiation schedules had longer survival; patients scored by GPA did not. This indicates GPA is more clinically useful, leaving less room for subjective treatment choices.

Proton therapy for atypical meningiomas.

We report clinical outcomes of proton therapy in patients with World Health Organization grade 2 (atypical) meningiomas. Between 2005 and 2013, 22 patients with atypical meningiomas were treated to a median dose of 63 Gy (RBE) using proton therapy, as an adjuvant therapy after surgery (n = 12) or for recurrence or progression of residual tumor (n = 10). Six patients had presumed radiation-induced meningiomas, but none had received prior radiotherapy for their meningioma. The median follow-up time after radiation was 39 months (range 7-104) and all patients remain alive at last follow-up. The 5-year estimate of local control was 71.1% (95% CI 49.3-92.9%). The 5-year estimate of local control was 87.5% following a radiation dose >60 Gy (RBE), compared to 50.0% for ≤ 60 Gy (RBE) (p = 0.038). The 5-year estimate of neuraxis dissemination was 5% (95% CI 0-14.6%) and 6.2% (95% CI 0-18.2%) for metastases outside of the central nervous system. Radiation necrosis was observed in one patient with a history of prior cranial irradiation. Fractionated proton therapy was associated with favorable tumor control rates for grade 2 meningiomas. Prospective studies are needed to define the optimal radiation dose for high-grade meningiomas.

ACR Appropriateness Criteria® pre-irradiation evaluation and management of brain metastases.

Pretreatment evaluation is performed to determine the number, location, and size of the brain metastases and magnetic resonance imaging (MRI) is the recommended imaging technique, particularly in patients being considered for surgery or stereotactic radiosurgery. A contiguous thin-cut volumetric MRI with gadolinium with newer gadolinium-based agents can improve detection of small brain metastases. A systemic workup and medical evaluation are important, given that subsequent treatment for the brain metastases will also depend on the extent of the extracranial disease and on the age and performance status of the patient. Patients with hydrocephalus or impending brain herniation should be started on high doses of corticosteroids and evaluated for possible neurosurgical intervention. Patients with moderate symptoms should receive approximately 4-8 mg/d of dexamethasone in divided doses. The routine use of corticosteroids in patients without neurologic symptoms is not necessary. There is no proven benefit of anticonvulsants in patient without seizures. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

A phase I study of lapatinib with whole brain radiotherapy in patients with Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer brain metastases.

Brain metastases are common in patients with advanced, Human Epidermal Growth Factor Receptor 2 (HER2)-positive breast cancer. We evaluated the maximum tolerated dose (MTD) and feasibility of lapatinib given concurrently with whole brain radiotherapy (WBRT). Eligible patients had (HER2)-positive breast cancer and ≥1 brain metastasis. Patients received lapatinib 750 mg twice on day one followed by 1000, 1250, or 1500 mg once daily. WBRT (37.5 Gy, 15 fractions) began 1-8 days after starting lapatinib. Lapatinib was continued through WBRT. Following WBRT, patients received trastuzumab 2 mg/kg weekly and lapatinib 1000 mg once daily. The regimen would be considered feasible if <3/27 pts treated at the MTD experienced a dose-limiting toxicity (DLT). Thirty-five patients were enrolled; 17 % had central nervous disease (CNS) only. During dose escalation, no patients receiving 1,000 or 1,250 mg and two of five patients receiving 1,500 mg experienced DLTs (grade 3 mucositis and rash). Overall, 7/27 patients at 1,250 mg (MTD) had DLTs: grade 3 rash (n = 2), diarrhea (n = 2), hypoxia (n = 1), and grade 4 pulmonary embolus (n = 2). Among 28 evaluable patients, the CNS objective response rate (ORR) was 79 % [95% confidence interval (CI) 59-92 %] by pre-specified volumetric criteria; 46 % remained progression-free (CNS or non-CNS) at 6 months. The study did not meet the pre-defined criteria for feasibility because of toxicity, although the relationship between study treatment and some DLTs was uncertain. Given the high ORR, concurrent lapatinib-WBRT could still be considered for future study with careful safety monitoring.

Whole brain radiotherapy for poor prognosis patients with brain metastases: predictably poor results.

BACKGROUND: Patients with brain metastases from solid tumors can be subdivided by characteristics into separate prognostic groups, such as the Radiation Therapy Oncology Group's Recursive Partitioning Analysis (RPA) or the Graded Prognostic Assessment (GPA). At our institution, patients falling into the poorest prognostic groups are often treated with whole brain radiotherapy (WBRT). OBJECTIVE: To determine if observed survival of poor prognosis patients treated with WBRT for brain metastases at our institution matches the survival predicted by RPA and GPA prognostic indices. METHODS: The charts of 101 consecutive patients with newly diagnosed brain metastases from solid tumors who received WBRT were retrospectively reviewed. We calculated each patient's RPA and GPA and compiled treatment and survival data. Observed median survival was compared to that predicted by the RPA and GPA prognostic indices. RESULTS: RPA III patients (n = 25) had a median survival of 2.4 months in our study. GPA 0.0-1.0 patients (n = 35) had a median survival of 2.4 months in our study. These values did not vary significantly from those predicted by the respective indices. LIMITATIONS: This is a retrospective analysis and subject to selection bias. CONCLUSION: Given the delivery time for WBRT and the potential side effects associated with the treatment, the predictably short overall survival in poor prognosis patients calls into question the value of WBRT in this patient subgroup.

ACR Appropriateness Criteria® follow-up and retreatment of brain metastases.

Multiple options for retreatment are available, which include whole-brain radiation therapy, stereotactic radiosurgery, surgery, chemotherapy, and supportive care. Size, number, timing, location, histology, performance status, and extracranial disease status all need to be carefully considered when choosing a treatment modality. There are no randomized trials examining the retreatment of brain metastases. Repeat whole-brain radiation has been examined in a single-institution experience, showing the potential for clinical responses in selected patients. Local control rates as high as 91% using stereotactic radiosurgery for relapses after whole-brain radiation are reported. Surgery can be indicated in progressive and/or hemorrhagic lesions causing mass effect. The role of chemotherapy in the recurrent setting is limited but some agents may have activity on the basis of experiences on a smaller scale. Supportive care continues to be an important option, especially in those with a poor prognosis. Follow-up for brain metastases patients is discussed, examining the modality, frequency of imaging, and imaging options in differentiating treatment effect from recurrence. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of the current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Dosimetric comparison of metastatic spinal photon treatment techniques.

Traditional palliative treatment of metastatic cancer to the vertebral bodies often results in doses to the spinal cord that are higher than the dose prescribed to the target, or gross tumor volume (GTV). This study compares traditional techniques of spine palliation with intensity-modulated radiation therapy (IMRT). The purpose of the study is 2-fold: first, the study demonstrates the benefits of using IMRT to lower the dose to the organs at risk (OAR), particularly for the spinal cord and other nonspecified normal tissues; second, the article provides information regarding the advantages and disadvantages of commonly used conventional techniques for treating the vertebral bodies based on patient anatomy. Because the use of IMRT or other advanced techniques may be prohibitive because of insurance issues, treatment plans were created that compared optimal coverage vs. optimal sparing for single-field, wedged-pair, and opposed-beam arrangements. Fifty-five patients were selected and divided by location of target (cervical, thoracic, and lumbar spine) and also by the measured separation between the anterior and posterior surface of the patient at the level of mid-GTV. Within each anatomic category the patients again were divided into the categories of small, medium, and large based on separation. The patient dataset that most closely represented the average separation within each category was selected, resulting in a total of 9 patients, and the appropriate treatment plan techniques were calculated for each of the 9 patients. The results of the study do show that the use of IMRT is far superior when compared with other techniques, both for coverage and for sparing of the surrounding tissue, regardless of patient size and the section of spine being treated. Based on a combination of both target coverage and sparing of normal tissues, the conventional plan of choice may vary by both the section of spine to be treated and by the size of the patient.

A dose-volume analysis of radiation pneumonitis in non-small cell lung cancer patients treated with stereotactic body radiation therapy.

PURPOSE: To examine the rates and risk factors of radiation pneumonitis (RP) in non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT). METHODS AND MATERIALS: Dosimetry records for 251 patients with lymph node-negative Stage I-IIB NSCLC and no prior chest radiation therapy (RT) treated with SBRT were reviewed. Patients were coded on the basis of the presence of at least Grade (G) 2 RP using the Common Toxicity Criteria version 2 criteria. Radiation doses, V5, V10, V20, and mean lung dose (MLD) data points were extracted from the dose-volume histogram (DVH). RESULTS: Median PTV volume was 48 cc. Median prescribed radiation dose was 60 Gy delivered in three fractions to the 80% isodose line. Median age at treatment was 74 years. Median follow-up was 17 months. RP was reported after treatment of 42 lesions: G1 in 19 (8%), G2 in 17 (7%), G3 in 5 (2%), and G4 in 1 (0.4%). Total lung DVHs were available for 143 patients. For evaluable patients, median MLD, V5, V10, and V20 were 4.1 Gy, 20%, 12%, and 4%, respectively. Median MLDs were 4 Gy and 5 Gy for G0-1 and G2-4 groups, respectively (p = 0.14); median V5 was 20% for G0-1 and 24% for G2-4 (p = 0.70); median V10 was 12% in G0-1 and 16% in G2-4 (p = 0.08), and median V20 was 4% in G0-1 and 6.6% in G2-4 (p = 0.05). G2-4 RP was noted in 4.3% of patients with MLD ≤4 Gy compared with 17.6% of patients with MLD >4 Gy (p = 0.02), and in 4.3% of patients with V20 ≤4% compared with 16.4% of patients with V20 >4% (p = 0.03). CONCLUSION: Overall rate of G2-4 RP in our population treated with SBRT was 9.4%. Development of symptomatic RP in this series correlated with MLD and V20.

Evaluation of response after stereotactic body radiotherapy for hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is increasing in incidence due to hepatitis C. Stereotactic body radiotherapy (SBRT) is a noninvasive, effective therapy in the management of liver malignancies. The authors evaluated radiological response in 26 patients with HCC treated with SBRT at Indiana University. METHODS: Between March 2005 and June 2008, 26 patients with HCC who were not surgical candidates were enrolled in a phase 1 to 2 trial. Eligibility criteria included solitary tumors ≤ 6 cm or up to 3 lesions with sum diameters ≤ 6 cm, and well-compensated cirrhosis. All patients had imaging before, at 1 to 3 months, and every 3 to 6 months after SBRT. RESULTS: Patients received 3 to 5 fractions of SBRT. Median SBRT dose was 42 Gray (Gy) (range: 24-48 Gy). Median follow-up was 13 months. Per Response Evaluation Criteria in Solid Tumors (RECIST), 4 patients had a complete response (CR), 15 had a partial response (PR), and 7 achieved stable disease (SD) at 12 months. One patient with SD experienced progression marginal to the treated area. The overall best response rate (CR + PR) was 73%. In comparison, by European Association for the Study of the Liver (EASL) criteria, 18 of 26 patients had ≥ 50% nonenhancement at 12 months. Thirteen of 18 demonstrated 100% nonenhancement, being > 50% in 5 patients. Kaplan-Meier 1- and 2-year survival estimates were 77% and 60%, respectively. CONCLUSIONS: SBRT is effective therapy for patients with HCC with an overall best response rate (CR + PR) of 73%. Nonenhancement on imaging, a surrogate for ablation, may be a more useful indicator than size reduction in evaluating HCC response to SBRT in the first 6 to 12 months, supporting EASL criteria.

Chest wall toxicity after stereotactic body radiotherapy for malignant lesions of the lung and liver.

PURPOSE: To quantify the frequency of rib fracture and chest wall (CW) pain and identify the dose-volume parameters that predict CW toxicity after stereotactic body radiotherapy (SBRT). METHODS AND MATERIALS: The records of patients treated with SBRT between 2000 and 2008 were reviewed, and toxicity was scored according to Common Terminology Criteria for Adverse Events v3.0 for pain and rib fracture. Dosimetric data for CW and rib were analyzed and related to the frequency of toxicity. The risks of CW toxicity were then further characterized according to the median effective concentration (EC(50)) dose-response model. RESULTS: A total of 347 lesions were treated with a median follow-up of 19 months. Frequency of Grade I and higher CW pain and/or fracture for CW vs. non-CW lesions was 21% vs. 4%, respectively (p < 0.0001). A dose of 50 Gy was the cutoff for maximum dose (Dmax) to CW and rib above which there was a significant increase in the frequency of any grade pain and fracture (p = 0.03 and p = 0.025, respectively). Volume of CW receiving 15 Gy - 40 Gy was highly predictive of toxicity (R(2) > 0.9). According to the EC(50) model, 5 cc and 15 cc of CW receiving 40 Gy predict a 10% and 30% risk of CW toxicity, respectively. CONCLUSION: Adequate tumor coverage remains the primary objective when treating lung or liver lesions with SBRT. To minimize toxicity when treating lesions in close proximity to the CW, Dmax of the CW and/or ribs should remain <50 Gy, and <5 cc of CW should receive ≥ 40 Gy.

Phase I feasibility trial of stereotactic body radiation therapy for primary hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is increasing in incidence and the majority of patients are not candidates for radical therapies. Therefore, interest in minimally invasive therapies in growing. METHODS: A Phase I dose escalation trial was conducted at Indiana University to determine the feasibility and toxicity of stereotactic body radiation therapy (SBRT) for primary HCC. Eligible patients had Child-Turcotte-Pugh's Class (CTP) A or B, were not candidates for resection, had 1-3 lesions and cumulative tumour diameter less than or equal to 6 cm. Dose escalation started at 36 Gy in 3 fractions (12 Gy/fraction) with a subsequent planned escalation of 2 Gy/ fraction/level. Dose-limiting toxicity (DLT) was defined as Common Terminology Criteria for Adverse Events v3.0 grade 3 or greater toxicity. RESULTS: Seventeen patients with 25 lesions were enrolled. Dose was escalated to 48 Gy (16 Gy/fraction) in CTP-A patients without DLT. Two patients with CPC-B disease developed grade 3 hepatic toxicity at the 42-Gy (14 Gy/fraction) level. The protocol was amended for subsequent CTP-B patients to receive a regimen of 5 fractions starting at 40 Gy (8 Gy/fraction) with one patient experiencing progressive liver failure. Four additional patients were enrolled (one died of unrelated causes after an incomplete SBRT course) without DLT. The only factor related to more than one grade 3 or greater liver toxicity or death within 6 months was the CTP score (p=0.03). Six patients underwent a liver transplant. Ten patients are alive without progression with a median FU of 24 months (10-42 months), with local control/stabilisation of the disease of 100%. One and two-year Kaplan-Meier estimates for overall survival are 75% and 60%, respectively. CONCLUSIONS: SBRT is a non-invasive feasible and well tolerated therapy in adequately selected patients with HCC. The preliminary local control and survival are encouraging. A confirmatory Phase II trial is currently open to accrual.