12 results on '"Yr, Lawrence"'
Search Results
2. Single-Fraction Celiac Plexus Radiosurgery: A Preliminary Proof-of-Concept Phase 2 Clinical Trial.
- Author
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Hammer L, Hausner D, Ben-Ayun M, Shacham-Shmueli E, Morag O, Margalit O, Boursi B, Yarom N, Jacobson G, Katzman T, Abrams R, Dicker A, Golan T, Symon Z, and Lawrence YR
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- Aged, Humans, Prospective Studies, Pancreatic Neoplasms, Cancer Pain etiology, Cancer Pain radiotherapy, Celiac Plexus, Pancreatic Neoplasms complications, Pancreatic Neoplasms radiotherapy, Radiosurgery adverse effects
- Abstract
Background: Refractory epigastric/midback pain is associated with locally advanced abdominal malignancies, especially pancreatic cancer. The pain is caused by tumor infiltration of the celiac plexus, a nerve network attached to the abdominal aorta. Contemporary palliative approaches are often inadequate. We hypothesized that ablative radiation targeted to the celiac plexus would alleviate this pain., Methods and Materials: We performed a single-arm prospective clinical trial (ClinicalTrials.gov identifier: NCT02356406). Eligible and evaluable patients had celiac pain of at least 5 out of 10 on the Numerical Rating Scale, completed treatment per protocol, and had at least 1 posttreatment visit. The entire retroperitoneal celiac plexus was irradiated with a single 25-Gy fraction. The primary endpoint was change in the Numerical Rating Scale 3 weeks posttreatment. Toxic effects and pain interference (as measured with the Brief Pain Inventory) were secondary endpoints., Results: For our study, 31 patients signed consent, and, of these, 18 patients were treated and evaluable. Median age was 68 years (range, 51-79); 89% of the patients had pancreatic cancer; the median Eastern Cooperative Oncology Group performance status was 1; and the median interval from initial diagnosis to treatment was 9 months (range, 1-36), and, in this interval, patients received a median of 1 systemic treatment line (range, 0-3). Acute toxicity was limited to grade 1 to 2. Three weeks after treatment, 16 patients (84%) reported decreased celiac pain, with median pain level falling from 6 out of 10 (interquartile range [IQR], 5.0-7.5) at baseline to 3 out of 10 (IQR, 1.0-4.3); six weeks after treatment, the Numerical Rating Scale number fell further to 2.8 out of 10 (IQR, 0-3.3; both P < .005 vs baseline), including 4 patients who reported complete eradication of their celiac pain. Total daily morphine milligram equivalents decreased from 59 pretreatment to 50 at 3 weeks, and from 50 to 45 at 6 weeks. Significant improvement was seen in pain-interference scores., Conclusions: Celiac plexus radiosurgery appears to alleviate cancer-related pain. An international multicenter phase 2 trial is currently accruing., (Copyright © 2022 Elsevier Inc. All rights reserved.)
- Published
- 2022
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3. Benefits of Continuous Positive Airway Pressure (CPAP) During Radiation Therapy: A Prospective Trial.
- Author
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Jacobson G, Lawrence YR, Appel S, Weiss I, Ben Ayun M, Akiva Ben-David M, Peled N, Goldstein JD, Weizman N, Galper S, Kaidar-Person O, and Symon Z
- Subjects
- Adult, Aged, Aged, 80 and over, Female, Four-Dimensional Computed Tomography, Heart radiation effects, Humans, Imaging, Three-Dimensional, Liver Neoplasms diagnostic imaging, Liver Neoplasms secondary, Lung radiation effects, Lung Neoplasms diagnostic imaging, Lung Neoplasms secondary, Lung Volume Measurements, Male, Middle Aged, Organ Motion, Prospective Studies, Radiation Pneumonitis etiology, Respiration, Tomography, X-Ray Computed, Unilateral Breast Neoplasms diagnostic imaging, Continuous Positive Airway Pressure statistics & numerical data, Liver Neoplasms radiotherapy, Lung Neoplasms radiotherapy, Unilateral Breast Neoplasms radiotherapy
- Abstract
Purpose: This study aimed to study the impact of continuous positive airway pressure (CPAP) on chest anatomy and tumor motion in patients receiving radiation therapy., Methods and Materials: Patients with primary or secondary lung tumors, left-sided breast cancer, or liver metastases referred for radiation therapy were trained to breathe with a CPAP device using a face mask to a maximal pressure of 15 cm H
2 O. Three- and 4-dimensional computed tomography simulation was performed twice for each patient: once with free breathing (FB) and again using CPAP. Volumetric and dosimetric parameters of treatment plans were compared., Results: Forty-nine patients were enrolled, of whom 6 withdrew consent before simulation and 3 withdrew because of discomfort. Thus, a total of 40 patients were analyzed. Twenty-seven patients (67.5%) were treated with CPAP based on confirmation of the volumetric or dosimetric benefit of CPAP. Mean lung volume increased by 37% (P < .001). The mean augmentation was 1283 ± 1128 cm3 (CPAP vs FB; P = .0006) in patients with normal lung function tests and 719 ± 341 cm3 (P = .003) in patients with a restrictive pattern. Increased lung volume was independent of age, body mass index, sex, chronic obstructive pulmonary disease, smoking status, and heart disease. Tumor motion in the lung was decreased as reflected in a mean reduction of planning target volume by 19% (P < .001). The greatest reduction of tumor trajectory and planning target volume occurred in tumors in the lower lung, particularly in the range of up to 6 cm above the dome of the diaphragm. The mean lung dose was reduced by 15%, lung V20 by 20%, lung V5 by 11%, and heart V5 by 16% (P < .01)., Conclusions: In this prospective trial, the use of CPAP was associated with significant volumetric and dosimetric benefits compared with FB. CPAP was safe, simple to implement, and well tolerated by most patients, and it should be studied further as a method to reduce the risk of lung and heart toxicity., (Copyright © 2021 Elsevier Inc. All rights reserved.)- Published
- 2021
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4. Continuous Positive Airway Pressure for Motion Management in Stereotactic Body Radiation Therapy to the Lung: A Controlled Pilot Study.
- Author
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Goldstein JD, Lawrence YR, Appel S, Landau E, Ben-David MA, Rabin T, Benayun M, Dubinski S, Weizman N, Alezra D, Gnessin H, Goldstein AM, Baidun K, Segel MJ, Peled N, and Symon Z
- Subjects
- Adult, Aged, Confidence Intervals, Feasibility Studies, Female, Four-Dimensional Computed Tomography, Humans, Lung Neoplasms diagnostic imaging, Male, Middle Aged, Pilot Projects, Radiotherapy Planning, Computer-Assisted methods, Statistics, Nonparametric, Continuous Positive Airway Pressure, Lung Neoplasms surgery, Movement, Radiosurgery methods, Respiration
- Abstract
Objective: To determine the effect of continuous positive airway pressure (CPAP) on tumor motion, lung volume, and dose to critical organs in patients receiving stereotactic body radiation therapy (SBRT) for lung tumors., Methods and Materials: After institutional review board approval in December 2013, patients with primary or secondary lung tumors referred for SBRT underwent 4-dimensional computed tomographic simulation twice: with free breathing and with CPAP. Tumor excursion was calculated by subtracting the vector of the greatest dimension of the gross tumor volume (GTV) from the internal target volume (ITV). Volumetric and dosimetric determinations were compared with the Wilcoxon signed-rank test. CPAP was used during treatment if judged beneficial., Results: CPAP was tolerated well in 10 of the 11 patients enrolled. Ten patients with 18 lesions were evaluated. The use of CPAP decreased tumor excursion by 0.5 ± 0.8 cm, 0.4 ± 0.7 cm, and 0.6 ± 0.8 cm in the superior-inferior, right-left, and anterior-posterior planes, respectively (P ≤ .02). Relative to free breathing, the mean ITV reduction was 27% (95% confidence interval [CI] 16%-39%, P<.001). CPAP significantly augmented lung volume, with a mean absolute increase of 915 ± 432 cm(3) and a relative increase of 32% (95% CI 21%-42%, P=.003), contributing to a 22% relative reduction (95% CI 13%-32%, P=.001) in mean lung dose. The use of CPAP was also associated with a relative reduction in mean heart dose by 29% (95% CI 23%-36%, P=.001)., Conclusion: In this pilot study, CPAP significantly reduced lung tumor motion compared with free breathing. The smaller ITV, the planning target volume (PTV), and the increase in total lung volume associated with CPAP contributed to a reduction in lung and heart dose. CPAP was well tolerated, reproducible, and simple to implement in the treatment room and should be evaluated further as a novel strategy for motion management in radiation therapy., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
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5. In reply to Franken and Barendsen.
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Lawrence YR, Dicker AP, and Ohri N
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- Humans, Dose Fractionation, Radiation, Models, Biological, Neoplasms radiotherapy, Radiation Tolerance drug effects, Radiation-Sensitizing Agents pharmacology
- Published
- 2013
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6. A phase I study of the combination of sorafenib with temozolomide and radiation therapy for the treatment of primary and recurrent high-grade gliomas.
- Author
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Den RB, Kamrava M, Sheng Z, Werner-Wasik M, Dougherty E, Marinucchi M, Lawrence YR, Hegarty S, Hyslop T, Andrews DW, Glass J, Friedman DP, Green MR, Camphausen K, and Dicker AP
- Subjects
- Adult, Aged, Antineoplastic Combined Chemotherapy Protocols administration & dosage, Brain Neoplasms blood supply, Brain Neoplasms mortality, Brain Neoplasms pathology, Cell Line, Tumor, Cell Survival drug effects, Cell Survival radiation effects, Chemoradiotherapy adverse effects, Dacarbazine administration & dosage, Dacarbazine therapeutic use, Female, Glioma blood supply, Glioma mortality, Glioma pathology, Humans, Male, Maximum Tolerated Dose, Middle Aged, Neoplasm Proteins blood, Neoplasm Recurrence, Local blood supply, Neoplasm Recurrence, Local mortality, Neoplasm Recurrence, Local pathology, Niacinamide administration & dosage, Niacinamide adverse effects, Niacinamide therapeutic use, Phenylurea Compounds administration & dosage, Phenylurea Compounds adverse effects, Radiotherapy Dosage, Sorafenib, Temozolomide, Vascular Endothelial Growth Factor A blood, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Brain Neoplasms therapy, Chemoradiotherapy methods, Dacarbazine analogs & derivatives, Glioma therapy, Neoplasm Recurrence, Local therapy, Niacinamide analogs & derivatives, Phenylurea Compounds therapeutic use
- Abstract
Purpose: Despite recent advances in the management of high-grade and recurrent gliomas, survival remains poor. Antiangiogenic therapy has been shown to be efficacious in the treatment of high-grade gliomas both in preclinical models and in clinical trials. We sought to determine the safety and maximum tolerated dose of sorafenib when combined with both radiation and temozolomide in the primary setting or radiation alone in the recurrent setting., Methods and Materials: This was a preclinical study and an open-label phase I dose escalation trial. Multiple glioma cell lines were analyzed for viability after treatment with radiation, temozolomide, or sorafenib or combinations of them. For patients with primary disease, sorafenib was given concurrently with temozolomide (75 mg/m(2)) and 60 Gy radiation, for 30 days after completion of radiation. For patients with recurrent disease, sorafenib was combined with a hypofractionated course of radiation (35 Gy in 10 fractions)., Results: Cell viability was significantly reduced with the combination of radiation, temozolomide, and sorafenib or radiation and sorafenib. Eighteen patients (11 in the primary cohort, 7 in the recurrent cohort) were enrolled onto this trial approved by the institutional review board. All patients completed the planned course of radiation therapy. The most common toxicities were hematologic, fatigue, and rash. There were 18 grade 3 or higher toxicities. The median overall survival was 18 months for the entire population., Conclusions: Sorafenib can be safely combined with radiation and temozolomide in patients with high-grade glioma and with radiation alone in patients with recurrent glioma. The recommended phase II dose of sorafenib is 200 mg twice daily when combined with temozolomide and radiation and 400 mg with radiation alone. To our knowledge, this is the first publication of concurrent sorafenib with radiation monotherapy or combined with radiation and temozolomide., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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7. Quality assurance peer review chart rounds in 2011: a survey of academic institutions in the United States.
- Author
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Lawrence YR, Whiton MA, Symon Z, Wuthrick EJ, Doyle L, Harrison AS, and Dicker AP
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- Academies and Institutes standards, Academies and Institutes statistics & numerical data, Brachytherapy standards, Brachytherapy statistics & numerical data, Health Care Surveys, Health Physics statistics & numerical data, Humans, Internship and Residency statistics & numerical data, Peer Review, Health Care methods, Radiation Oncology standards, Radiation Oncology statistics & numerical data, Radiosurgery standards, Radiosurgery statistics & numerical data, Radiotherapy statistics & numerical data, Radiotherapy, Intensity-Modulated standards, Radiotherapy, Intensity-Modulated statistics & numerical data, United States, Peer Review, Health Care standards, Quality Assurance, Health Care methods, Radiotherapy standards
- Abstract
Purpose: In light of concerns regarding the quality of radiation treatment delivery, we surveyed the practice of quality assurance peer review chart rounds at American academic institutions., Methods and Materials: An anonymous web-based survey was sent to the chief resident of each institution across the United States., Results: The response rate was 80% (57/71). The median amount of time spent per patient was 2.7 minutes (range, 0.6-14.4). The mean attendance by senior physicians and residents was 73% and 93%, respectively. A physicist was consistently present at peer review rounds in 66% of departments. There was a close association between attendance by senior physicians and departmental organization: in departments with protected time policies, good attendance was 81% vs. 31% without protected time (p = 0.001), and in departments that documented attendance, attending presence was 69% vs. 29% in departments without documentation (p < 0.05). More than 80% of institutions peer review all external beam therapy courses; however, rates were much lower for other modalities (radiosurgery 58%, brachytherapy 40%-47%). Patient history, chart documentation, and dose prescription were always peer reviewed in >75% of institutions, whereas dosimetric details (beams, wedges), isodose coverage, intensity-modulated radiation therapy constraints, and dose-volume histograms were always peer reviewed in 63%, 59%, 42%, and 50% of cases, respectively. Chart rounds led to both minor (defined as a small multileaf collimator change/repeated port film) and major (change to dose prescription or replan with dosimetry) treatment changes. Whereas at the majority of institutions changes were rare (<10% of cases), 39% and 11% of institutions reported that minor and major changes, respectively, were made to more than 10% of cases., Conclusion: The implementation of peer review chart rounds seems inconsistent across American academic institutions. Brachytherapy and radiosurgical procedures are rarely reviewed. Attendance by senior physicians is variable, but it improves when scheduling clashes are avoided. The potential effect of a more thorough quality assurance peer review on patient outcomes is not known., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
- Full Text
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8. Radiotherapy improves survival in unresected stage I-III bronchoalveolar carcinoma.
- Author
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Urban D, Mishra M, Onn A, Dicker AP, Symon Z, Pfeffer MR, and Lawrence YR
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- Adenocarcinoma, Bronchiolo-Alveolar mortality, Adenocarcinoma, Bronchiolo-Alveolar pathology, Adolescent, Adult, Age Factors, Aged, Aged, 80 and over, Carcinoma, Non-Small-Cell Lung mortality, Carcinoma, Non-Small-Cell Lung pathology, Child, Female, Humans, Lung Neoplasms mortality, Lung Neoplasms pathology, Male, Middle Aged, Prognosis, SEER Program, Sex Factors, Treatment Outcome, Young Adult, Adenocarcinoma, Bronchiolo-Alveolar radiotherapy, Carcinoma, Non-Small-Cell Lung radiotherapy, Lung Neoplasms radiotherapy
- Abstract
Purpose: To test the hypothesis that radiotherapy (RT) improves the outcome of patients with unresected, nonmetastatic bronchoalveolar carcinoma (BAC) by performing a population-based analysis within the Surveillance, Epidemiology, and End Results (SEER) registry., Methods and Materials: Inclusion criteria were as follows: patients diagnosed with BAC, Stage I-III, between 2001 and 2007. Exclusion criteria included unknown stage, unknown primary treatment modality, Stage IV disease, and those diagnosed at autopsy. Demographic data, treatment details, and overall survival were retrieved from the SEER database. Survival was analyzed using the Kaplan-Meier method and log-rank test., Results: A total of 6933 patients with Stage I-III BAC were included in the analysis. The median age at diagnosis was 70 years (range, 10-101 years). The majority of patients were diagnosed with Stage I (74.4%); 968 patients (14%) did not undergo surgical resection. Unresected patients were more likely to be older (p < 0.0001), male (p = 0.001), black (p < 0.0001), and Stage III (p < 0.0001). Within the cohort of unresected patients, 300 (31%) were treated with RT. The estimated 2-year overall survival for patients with unresected, nonmetastatic BAC was 58%, 44%, and 27% in Stage I, II, and III, respectively. Factors associated with improved survival included female sex, earlier stage at diagnosis, and use of RT. Median survival in those not receiving RT vs. receiving RT was as follows: Stage I, 28 months vs. 33 months (n = 364, p = 0.06); Stage II, 18 months vs. not reached (n = 31, nonsignificant); Stage III, 10 months vs. 17 months (n = 517, p < 0.003)., Conclusions: The use of RT is associated with improved prognosis in unresected Stage I-III BAC. Less than a third of patients who could have potentially benefited from RT received it, suggesting that the medical specialists involved in the care of these patients underappreciate the importance of RT., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
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9. Implanted dosimeters identify radiation overdoses during IMRT for prostate cancer.
- Author
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Den RB, Nowak K, Buzurovic I, Cao J, Harrison AS, Lawrence YR, Dicker AP, and Showalter TN
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- Cone-Beam Computed Tomography, Humans, Male, Movement, Prostate diagnostic imaging, Prostatic Neoplasms diagnostic imaging, Radiometry instrumentation, Radiotherapy Planning, Computer-Assisted, Radiotherapy, Image-Guided methods, Radiotherapy, Intensity-Modulated methods, Prostatic Neoplasms radiotherapy, Radiotherapy Dosage, Radiotherapy, Image-Guided instrumentation, Radiotherapy, Intensity-Modulated instrumentation
- Abstract
Purpose: Image-guided dose-escalated radiotherapy is the standard of care for the treatment of prostate cancer. Although many published methods are available that account for prostate motion during delivery, evidence demonstrating that the planned dose is actually delivered on a daily basis is lacking. We report our initial clinical experience using implantable dosimeters to quantify and adjust the dose received during intensity-modulated radiotherapy (IMRT)., Methods and Materials: A total of 20 patients undergoing IMRT with cone-beam computed tomography (CT) image guidance for prostate cancer had the dose verification system with radiopaque metal-oxide-semiconductor field effect transistor dosimeters implanted before treatment planning. All patients underwent planning with CT simulation in the supine position with custom immobilization, and the implanted dosimeters were located in the IMRT plans. The predicted dose for each dosimeter was defined and compared with the wireless readings before and after each treatment session. Investigations by physicians and medical physicists were initiated for two or more discrepancies >6% for any five consecutive fractions or for any discrepancy ≥10%., Results: Using implanted in vivo dosimeters, dose measurements consistently >6% greater than the predicted values were observed during treatment for 3 of 20 prostate cancer patients who received IMRT with daily image guidance. A review of the daily cone-beam CT images revealed acceptable alignment of the prostate target volumes and implanted dosimeters but identified significant anatomic changes within the treated region. Repeat CT simulation and RT planning was performed, with resolution of the dose discrepancies in all 3 cases with the adoption of a new IMRT plan., Conclusions: Our report illustrates the potential effect of implanted in vivo dosimetry for prostate IMRT and emphasizes the importance of careful planning and delivery with attention to systematic shifts or anatomic changes that could alter the dose distributions., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
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10. Can drugs enhance hypofractionated radiotherapy? A novel method of modeling radiosensitization using in vitro data.
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Ohri N, Dicker AP, and Lawrence YR
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- Brain Neoplasms radiotherapy, Carcinoma, Non-Small-Cell Lung radiotherapy, Cell Line, Tumor, Cell Survival drug effects, Cell Survival physiology, Cell Survival radiation effects, Glioblastoma radiotherapy, Head and Neck Neoplasms radiotherapy, Humans, Linear Models, Lung Neoplasms radiotherapy, Pancreatic Neoplasms radiotherapy, Radiation Tolerance physiology, Relative Biological Effectiveness, Dose Fractionation, Radiation, Models, Biological, Neoplasms radiotherapy, Radiation Tolerance drug effects, Radiation-Sensitizing Agents pharmacology
- Abstract
Purpose: Hypofractionated radiotherapy (hRT) is being explored for a number of malignancies. The potential benefit of giving concurrent chemotherapy with hRT is not known. We sought to predict the effects of combined modality treatments by using mathematical models derived from laboratory data., Methods and Materials: Data from 26 published clonogenic survival assays for cancer cell lines with and without the use of radiosensitizing chemotherapy were collected. The first three data points of the RT arm of each assay were used to derive parameters for the linear quadratic (LQ) model, the multitarget (MT) model, and the generalized linear quadratic (gLQ) model. For each assay and model, the difference between the predicted and observed surviving fractions at the highest tested RT dose was calculated. The gLQ model was fitted to all the data from each RT cell survival assay, and the biologically equivalent doses in 2-Gy fractions (EQD2s) of clinically relevant hRT regimens were calculated. The increase in cell kill conferred by the addition of chemotherapy was used to estimate the EQD2 of hRT along with a radiosensitizing agent. For comparison, this was repeated using conventionally fractionated RT regimens., Results: At a mean RT dose of 8.0 Gy, the average errors for the LQ, MT, and gLQ models were 1.63, 0.83, and 0.56 log units, respectively, favoring the gLQ model (p < 0.05). Radiosensitizing chemotherapy increased the EQD2 of hRT schedules by an average of 28% to 82%, depending on disease site. This increase was similar to the gains predicted for the addition of chemotherapy to conventionally fractionated RT., Conclusions: Based on published in vitro assays, the gLQ equation is superior to the LQ and MT models in predicting cell kill at high doses of RT. Modeling exercises demonstrate that significant increases in biologically equivalent dose may be achieved with the addition of radiosensitizing agents to hRT. Clinical study of this approach is warranted., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
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11. Epidermal growth factor receptor expression modulates antitumor efficacy of vandetanib or cediranib combined with radiotherapy in human glioblastoma xenografts.
- Author
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Wachsberger PR, Lawrence YR, Liu Y, Daroczi B, Xu X, and Dicker AP
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- Animals, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Biomarkers, Tumor metabolism, Cell Line, Tumor, Chemoradiotherapy methods, Drug Administration Schedule, Glioblastoma metabolism, Glioblastoma pathology, Humans, Mice, Mice, Nude, Radiation Tolerance, Tumor Burden, Xenograft Model Antitumor Assays, Antineoplastic Agents therapeutic use, ErbB Receptors metabolism, Glioblastoma therapy, Neoplasm Proteins metabolism, Piperidines therapeutic use, Quinazolines therapeutic use, Receptors, Vascular Endothelial Growth Factor antagonists & inhibitors
- Abstract
Purpose: The purpose of this study was to determine the ability of radiation therapy (RT) combined with the tyrosine kinase inhibitors (TKI) vandetanib (antiepidermal growth factor receptor [EGFR] plus antivascular endothelial growth factor receptor [anti-VEGFR]) and cediranib (anti-VEGFR) to inhibit glioblastoma multiforme (GBM) growth. A secondary aim was to investigate how this regimen is modulated by tumor EGFR expression., Methods and Materials: Radiosensitivity was assessed by clonogenic cell survival assay. VEGF secretion was quantified by enzyme-linked immunosorbent assay. GBM (U87MG wild-type EGFR [wtEGFR] and U87MG EGFR-null) xenografts were treated with vandetanib, cediranib, and RT, alone or in combinations. Excised tumor sections were stained for proliferative and survival biomarkers., Results: In vitro, U87MG wtEGFR and U87 EGFR-null cells had similar growth kinetics. Neither TKI affected clonogenic cell survival following RT. However, in vivo, exogenous overexpression of wtEGFR decreased tumor doubling time (T2x) in U87MG xenografts (2.70 vs. 4.41 days for U87MG wtEGFR vs. U87MG vector, respectively). In U87MG EGFR-null cells, TKI combined with radiation was no better than radiation therapy alone. In U87MG wtEGFR, RT in combination with vandetanib (but not with cediranib) significantly increased tumor T2x compared with RT alone (T2x, 10.4 days vs. 4.8 days; p < 0.001). In vivo, growth delay correlated with suppression of pAkt, survivin, and Ki67 expression in tumor samples. The presence of EGFR augmented RT-stimulated VEGF release; this effect was inhibited by vandetanib., Conclusions: EGFR expression promoted tumor growth in vivo but not in vitro, suggesting a microenvironmental effect. GBM xenografts expressing EGFR exhibited greater sensitivity to both cediranib and vandetanib than EGFR-null tumors. Hence EGFR status plays a major role in determining a tumor's in vivo response to radiation combined with TKI, supporting a "personalized" approach to GBM management., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
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12. Radiation dose-volume effects in the brain.
- Author
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Lawrence YR, Li XA, el Naqa I, Hahn CA, Marks LB, Merchant TE, and Dicker AP
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- Adult, Age Factors, Brain pathology, Cranial Irradiation adverse effects, Cranial Irradiation methods, Dose-Response Relationship, Radiation, Humans, Models, Biological, Models, Theoretical, Necrosis etiology, Radiation Tolerance, Radiosurgery methods, Brain radiation effects, Cognition Disorders etiology, Radiosurgery adverse effects
- Abstract
We have reviewed the published data regarding radiotherapy (RT)-induced brain injury. Radiation necrosis appears a median of 1-2 years after RT; however, cognitive decline develops over many years. The incidence and severity is dose and volume dependent and can also be increased by chemotherapy, age, diabetes, and spatial factors. For fractionated RT with a fraction size of <2.5 Gy, an incidence of radiation necrosis of 5% and 10% is predicted to occur at a biologically effective dose of 120 Gy (range, 100-140) and 150 Gy (range, 140-170), respectively. For twice-daily fractionation, a steep increase in toxicity appears to occur when the biologically effective dose is >80 Gy. For large fraction sizes (>or=2.5 Gy), the incidence and severity of toxicity is unpredictable. For single fraction radiosurgery, a clear correlation has been demonstrated between the target size and the risk of adverse events. Substantial variation among different centers' reported outcomes have prevented us from making toxicity-risk predictions. Cognitive dysfunction in children is largely seen for whole brain doses of >or=18 Gy. No substantial evidence has shown that RT induces irreversible cognitive decline in adults within 4 years of RT., (Copyright 2010 Elsevier Inc. All rights reserved.)
- Published
- 2010
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