Fabian Pohl

University Hospital Regensburg, Ratisbon, Bavaria, Germany

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Publications (44)101.71 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Prognosis in childhood cranio-pharyngioma, is frequently impaired due to sequelae. Radical surgery was the treatment of choice for decades. Even at experienced facilities radical surgery can result in hypothalamic disorders such as severe obesity. Objective: We analyzed, whether treatment strategies for childhood craniopharyngioma patients recruited in GPOH studies have changed during the last 12 years. Materials and methods: We compared the grade of pre-surgical hypothalamic involvement, treatment, degree of resection and grade of surgical hypothalamic lesions between patients recruited in KRANIOPHARYNGEOM 2000 (n=120; 2001-2007) and KRANIOPHARYNGEOM 2007 (n=106; 2007-2012). Results: The grade of initial hypothalamic involvement was similar in patients treated 2001-2007 and 2007-2012. The realized treatment was more radical (p=0.01) in patients recruited 2001-2007 (38%) when compared with patients treated 2007-2012 (18%). In patients with pre-surgical involvement of anterior/posterior hypothalamic areas, the rate of hypothalamus-sparing operations resulting in no (further) hypothalamic lesions was higher (p=0.005) in patients treated 2007-2012 (35%) in comparison with the 2001-2007 cohort (13%). Event-free-survival rates were similar in both cohorts. Conclusions: A trend towards less radical surgical approaches is observed, which was accompanied by a reduced rate of severe hypothalamic lesions. Radical surgery is not an appropriate treatment strategy in patients with hypothalamic involvement. Despite previous recommendations to centralize treatment at specialized centers, a trend towards further decentralization was seen.
    Klinische Pädiatrie 05/2014; 226(3):161-168. · 1.90 Impact Factor
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    ABSTRACT: Many cancer patients receive a central venous catheter or port system prior to therapy to assure correct drug administration. Even appropriate hygienic intervention maintenance carries the risk of contaminating the middle port (C-port) of a three-way cock (TWC), a risk that increases with the number of medical interventions. Because of the complexity of the cleaning procedure with disconnection and reconnection of the standard luer lock cap (referred as "intervention"), we compared luer lock caps with a "closed access system" consisting of a luer access split septum system with regard to process optimization (work simplification, process time), efficiency (costs) and hygiene (patient safety). For determination of process optimization the workflow of an intervention according to the usual practice and risks was depicted in a process diagram. For determining the actual process costs, we analyzed use of material and time parameters per intervention and used the process parameters for programming the process into a simulation run (n=1000) to determine the process costs as well as their differences (ACTUAL vs. NOMINAL) within the framework of a discrete event simulation.Additionally cultures were carried out at the TWC C-ports to evaluate possible contamination. With the closed access system, the mean working time of 5.5minutes could be reduced to 2.97minutes. The results for average process costs (labour and material costs per use) were 3.92 [euro sign] for luer lock caps and 2.55 [euro sign] for the closed access system. The hypothesis test (2-sample t-test, CI 0.95, p-value <0.05) confirmed the significance of the result.In 50 reviewed samples (TWC's), the contamination rate for the luer lock cap was 8% (4 out of 50 samples were positive), the contamination rate of the 50 samples with the closed access system was 0%.Possible hygienic risks (related to material, surroundings, staff handling) could be reduced by 65.38%. In the present research, the closed access system with a divided split septum was superior to conventional luer lock caps. The advantage of the closed access system lies in the simplified handling for staff, which results in a reduced risk of patient infection due to improved clinical hygiene.
    BMC Infectious Diseases 01/2014; 14(1):41. · 3.03 Impact Factor
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    ABSTRACT: The multikinase inhibitor sunitinib (S) seems to have promising potential in the treatment of thyroid cancer. We focused on the impact of S and/or irradiation (R) on mechanisms of apoptosis in follicular thyroid cancer cells. The effects of R, S and their combination were evaluated 2 and 4 days after treatment, using the human thyroid cancer cell line CGTH W-1. The transcription of genes involved in the regulation of apoptosis was investigated using quantitative real-time PCR. Western blot analyses of caspases and survivin were also performed. S elevated BAX (day 4), CASP9, CASP3, BIRC5 (day 4) and PRKACA (day 4) gene expression, whereas the mRNAs of BCL2, CASP8, PRKCA, ERK1, and ERK2 were not significantly changed. S, R and R+S clearly induced caspase-9 protein and elevated caspase-3 activity. Survivin was down-regulated at day 4 in control cells and the expression was blunted by S treatment. R+S induced survivin expression at day 2 followed by a reduction at day 4 of treatment. Sunitinib and the combined application with radiation induced apoptosis in follicular thyroid cancer cells via the intrinsic pathway of apoptosis. In addition, sunitinib might induce apoptosis via decreased expression of the anti-apoptotic protein survivin. These findings suggest the potential use of sunitinib for the treatment of poorly differentiated follicular thyroid carcinomas.
    Apoptosis 11/2013; · 4.07 Impact Factor
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    ABSTRACT: Background/Aims: Thyroid cancer accounts for about 1% of all cancer cases. Multikinase inhibitors like sunitinib (S) have a promising potential in thyroid cancer therapy. Therefore, the principal aim of this study was to investigate the impact of sunitinib on the secretion of cytokines of follicular thyroid cancer cells. Method: The effects of irradiation (R), S, and their combination (R+S) on cytokine secretion by the human thyroid cancer cell lines ML-1 and CGTH W-1 were evaluated after two (d2) and four days (d4) of treatment. Results: Multi-Analyte Profiling of cytokine release showed a decrease after S treatment (CGTH W-1: IFN-γ, IL-4, IL-8 d2, MIP-1a, MMP-2, TNF-α and TNF-β; ML-1: IFN-γ, IL-4, IL-6, IL-7, IL-8; MIP-1α, MMP-2, MCP-1, TNF-α and TNF-β). R elevated significantly the release of cytokines (exception ML-1: MCP-1, MMP-2; CGTH W-1: IL-4, TNF-β). In contrast, R+S treatment resulted in a reduction of IFN-γ, IL-4, and MMP-2 in both cell lines. IL-6, IL-8 and MCP-1 proteins in the supernatant correlated with the data obtained by quantitative RT-PCR. VEGFD mRNAs were significantly elevated by R+S. Conclusion: A target-based therapy with R+S changed VEGFD, IL-6 and IL-8 in follicular thyroid cancer cells. These in vitro-experiments suggest IL-6, IL-8, VEGFD and TNF-α as interesting biomarkers to be investigated in vivo. Different reactions of the cell lines under equal treatment might be due to their different origin and characteristics.
    Cellular Physiology and Biochemistry 07/2013; 32(1):154-170. · 3.42 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the impact of Cone Beam CT (CBCT) based setup correction on total dose distributions in fractionated frameless stereotactic radiation therapy of intracranial lesions. Ten patients with intracranial lesions treated with 30 Gy in 6 fractions were included in this study. Treatment planning was performed with Oncentra(R) for a SynergyS(R) (Elekta Ltd, Crawley, UK) linear accelerator with XVI(R) Cone Beam CT, and HexaPODTM couch top. Patients were immobilized by thermoplastic masks (BrainLab, Reuther). After initial patient setup with respect to lasers, a CBCT study was acquired and registered to the planning CT (PL-CT) study. Patient positioning was corrected according to the correction values (translational, rotational) calculated by the XVI(R) system. Afterwards a second CBCT study was acquired and registered to the PL-CT to confirm the accuracy of the corrections. An in-house developed software was used for rigid transformation of the PL-CT to the CBCT geometry, and dose calculations for each fraction were performed on the transformed CT. The total dose distribution was achieved by back-transformation and summation of the dose distributions of each fraction. Dose distributions based on PL-CT, CBCT (laser set-up), and final CBCT were compared to assess the influence of setup inaccuracies. The mean displacement vector, calculated over all treatments, was reduced from (4.3 +/- 1.3) mm for laser based setup to (0.5 +/- 0.2) mm if CBCT corrections were applied. The mean rotational errors around the medial-lateral, superior-inferior, anterior-posterior axis were reduced from (-0.1 +/- 1.4)[degree sign], (0.1 +/- 1.2)[degree sign] and (-0.2 +/- 1.0)[degree sign], to (0.04 +/- 0.4)[degree sign], (0.01 +/- 0.4)[degree sign] and (0.02 +/- 0.3)[degree sign]. As a consequence the mean deviation between planned and delivered dose in the planning target volume (PTV) could be reduced from 12.3% to 0.4% for D95 and from 5.9% to 0.1% for Dav. Maximum deviation was reduced from 31.8% to 0.8% for D95, and from 20.4% to 0.1% for Dav. Real dose distributions differ substantially from planned dose distributions, if setup is performed according to lasers only. Thermoplasic masks combined with a daily CBCT enabled a sufficient accuracy in dose distribution.
    Radiation Oncology 06/2013; 8(1):153. · 2.11 Impact Factor
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    ABSTRACT: BACKGROUND: The inflammatory response clinically observed after radiation has been described to correlate with elevated expression of cytokines and adhesion molecules by endothelial cells. Therapeutic compensation for this microvascular compromise could be an important approach in the treatment of irradiated wounds. Clinical reports describe the potential of adipose-derived stem cells to enhance wound healing, but the underlying cellular mechanisms remain largely unclear. METHODS: Human dermal microvascular endothelial cells (HDMEC) and human adipose-derived stem cells (ASC) were cultured in a co-culture setting and irradiated with sequential doses of 2 to 12 Gy. Cell count was determined 48 h after radiation using a semi-automated cell counting system. Levels of interleukin-6 (IL-6), basic fibroblast growth factor (FGF), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were determined in the supernatants using enzyme-linked immunosorbent assay (ELISA). Irradiated HDMEC and ASC as well as non-irradiated co-cultures, HDMEC or ASC respectively were used as controls. RESULTS: Cell count was significantly reduced in irradiated co-cultures of HDMEC and ASC compared to non-irradiated controls. Levels of IL-6, FGF, ICAM-1 and VCAM-1 in the supernatants of the co-cultures were significantly less affected by external radiation in comparison to HDMEC. CONCLUSION: The increased expression of cytokines and adhesion molecules by HDMEC after external radiation is mitigated in the co-culture setting with ASC. These in vitro changes seem to support the clinical observation that ASC may have a stabilizing effect when injected into irradiated wounds.
    Radiation Oncology 03/2013; 8(1):66. · 2.11 Impact Factor
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    ABSTRACT: Background: Radiation-induced wound healing complications represent an important clinical problem. Microvascular compromise is an important component of its pathogenesis and the microvascular endothelial cell is the key representative affected at the cellular level. Material and Methods: Human dermal microvascular endothelial cells (HDMEC) were cultured and irradiated with doses of 2 to 12 Gy. Cell density was determined 48 h after radiation using a semi-automated cell counting system. Levels of interleukin-6 (IL-6), basic fibroblast growth factor (FGF), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in the supernatants of HDMEC were determined by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Non irradiated HDMEC were used as controls. Results: Cell density was significantly impaired in irradiated cells compared to non irradiated controls. Radiation resulted in significant elevation of levels of IL-6, FGF, ICAM-1 and VCAM-1 in the supernatants of HDMEC in a dose dependent manner. Conclusion: The inflammatory response observed clinically after radiation seems to correlate with elevated expression of cytokines and adhesion molecules by microvascula endothelial cells. The model of HDMEC documents the impairment of microcirculation. These in vitro changes may enhance our understanding of the pathomechanisms leading to radiation-induced vasculitis and associated wound healing problems.
    Clinical hemorheology and microcirculation 10/2012; · 3.40 Impact Factor
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    ABSTRACT: Carbonic anhydrase (CA) IX is over-expressed in glioblastoma; however, its functions in this context are unknown. Metabolically, glioblastomas are highly glycolytic, leading to a significant lactic acid load. Paradoxically, the intracellular pH is alkaline. We hypothesized that CAIX contributes to the extrusion of hydrogen ions into the extracellular space, thereby moderating intra- and extracellular pH and creating an environment conductive to enhanced invasion. We investigated the role of CAIX as a prognostic marker in patients with glioblastoma and its biological function in vitro. CAIX expression was analyzed in 59 patients with glioblastoma by immunohistochemistry. The expression levels were correlated to overall survival. In vitro, U251 and Ln 18 glioblastoma cells were incubated under hypoxia to induce CAIX expression, and RNA interference (RNAi) was used to examine the function of CAIX on cell attachment, invasion, intracellular energy transfer, and susceptibility to adjuvant treatment. High CAIX expression was identified as an independent factor for poor survival in patients with glioblastoma. In vitro, cell attachment and invasion were strongly reduced after knockdown of CAIX. Finally, the effects of radiation and chemotherapy were strongly augmented after CAIX interference and were accompanied by a higher rate of apoptotic cell death. CAIX is an independent prognostic factor for poor outcome in patients with glioblastoma. Cell attachment, invasion, and survival during adjuvant treatment are significantly influenced by high CAIX expression. These results indicate that inhibition of CAIX is a potential metabolic target for the treatment of patients with glioblastoma.
    Neuro-Oncology 10/2012; 14(11):1357-66. · 6.18 Impact Factor
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    ABSTRACT: Radiation therapy is an established modality in the treatment of head and neck cancer patients. Compromised wound healing in irradiated tissues is a common and challenging clinical problem. The pathophysiology and underlying cellular mechanisms including the complex interaction of cytokines and growth factors are still not understood completely. In this review, the current state of research regarding the pathomechanisms of compromised wound healing in irradiated tissues is presented. Current and possible future treatment strategies are critically reviewed.
    Radiation Oncology 09/2012; 7(1). · 2.11 Impact Factor
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    ABSTRACT: Context:Craniopharyngioma (CP), Rathke's cyst (RC), and xanthogranuloma (XG) are closely related rare sellar masses. Treatment strategies in children lack consensus.Objective:Our objective was to study clinical manifestations and treatment-related outcome in RC, XG, and CP patients.Design:We conducted a multicenter surveillance trial.Patients:Inclusion criteria were 1) histological diagnosis of CP, XG, or RC and 2) diagnosis at age of 18 yr or less. A total of 117 CP, 14 XG (2001-2006), and 14 RC (1996-2006) were recruited.Main Outcome:Overall survival (OS), event-free survival (EFS), and quality of life (QoL) were evaluated.Results:The 5-yr OS rates were 1.00 ± 0.00 in RC and XG and 0.97 ± 0.02 in CP. The 5-yr EFS rates were 0.85 ± 0.10 in RC, 1.00 ± 0.00 in XG, and 0.50 ± 0.05 in CP. Surgical resection of XG results in complete remission without recurrence. Recurrences occur in RC (14%) and CR (59%) but can be efficiently treated by irradiation, reoperation, and/or intracystic treatment. Severe hypothalamic sequelae such as obesity and others affecting QoL are predominant in CP due to presurgical involvement (59%) and postsurgical lesions (44%) of posterior hypothalamic structures. Centers with lower neurosurgery patient load use more radical surgical approaches to treat CP, resulting in higher rates of obesity and reduced QoL. Despite 46% anterior hypothalamic involvement, severe obesity is not encountered in XG.Conclusions:Treatment of choice in XG and RC is radical surgery. In CP involving hypothalamic structures, less radical surgical approaches preserving hypothalamic integrity are recommended. Due to frequent relapses, regular imaging during follow-up is recommended for CP and RC. Treatment of patients with sellar masses should be confined to experienced multidisciplinary teams.
    The Journal of Clinical Endocrinology and Metabolism 09/2012; · 6.31 Impact Factor
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    ABSTRACT: This case study presents a rare case of left-sided breast cancer in a patient with funnel chest, which is a technical challenge for radiation therapy planning. To identify the best treatment technique for this case, 3 techniques were compared: conventional tangential fields (3D conformal radiotherapy [3D-CRT]), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT). The plans were created for a SynergyS® (Elekta, Ltd, Crawley, UK) linear accelerator with a BeamModulator™ head and 6-MV photons. The planning system was Oncentra Masterplan® v3.3 SP1 (Nucletron BV, Veenendal, Netherlands). Calculations were performed with collapsed cone algorithm. Dose prescription was 50.4 Gy to the average of the planning target volume (PTV). PTV coverage and homogeneity was comparable for all techniques. VMAT allowed reducing dose to the ipsilateral organs at risk (OAR) and the contralateral breast compared with IMRT and 3D-CRT: The volume of the left lung receiving 20 Gy was 19.3% for VMAT, 26.1% for IMRT, and 32.4% for 3D-CRT. In the heart, a D(15%) of 9.7 Gy could be achieved with VMAT compared with 14 Gy for IMRT and 46 Gy for 3D-CRT. In the contralateral breast, D(15%) was 6.4 Gy for VMAT, 8.8 Gy for IMRT, and 10.2 Gy for 3D-CRT. In the contralateral lung, however, the lowest dose was achieved with 3D-CRT with D(10%) of 1.7 Gy for 3D-CRT, and 6.7 Gy for both IMRT and VMAT. The lowest number of monitor units (MU) per 1.8-Gy fraction was required by 3D-CRT (192 MU) followed by VMAT (518 MU) and IMRT (727 MU). Treatment time was similar for 3D-CRT (3 min) and VMAT (4 min) but substantially increased for IMRT (13 min). VMAT is considered the best treatment option for the presented case of a patient with funnel chest. It allows reducing dose in most OAR without compromising target coverage, keeping delivery time well below 5 minutes.
    Medical dosimetry: official journal of the American Association of Medical Dosimetrists 06/2012; · 1.26 Impact Factor
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    ABSTRACT: Fanconi anaemia (FA) is a rare genetic syndrome characterized by progressive pancytopenia, variably expressed congenital abnormalities and susceptibility, amongst others, to solid tumours. Early detection by oral health professionals of a pathological process can have a critical impact on the clinical course of that condition. In this paper we report the case of a 27-year-old male patient with tonsillar squamous cell carcinoma (cT4 cN2b cM0 G3) associated with FA. Due to the locally advanced growth of the tumour and the poor systemic condition we ruled out primary surgery and settled for primary radio- and chemotherapy. Given the poor clinical course a focus on the aspect of secondary prevention is reasonable, given that it is known that patients with FA are at higher risk of developing malignancy than the general population. A multi-disciplinary approach is necessary in which the prevention of, surveillance for and the treatment of malignancies are important aspects of management and may improve disease-free survival.
    Journal of cranio-maxillo-facial surgery: official publication of the European Association for Cranio-Maxillo-Facial Surgery 09/2011; 40(6):510-5. · 1.25 Impact Factor
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    ABSTRACT: Hypothalamic obesity has major impact on prognosis and quality of life (QoL) in childhood craniopharyngioma. For this study, 120 patients were prospectively recruited during 2001 and 2007 and evaluated after 3 years of follow-up (KRANIOPHARYNGEOM 2000). Body mass index (BMI) and QoL at diagnosis and 36 months after diagnosis were analysed based on the reference assessment of tumour localisation and post-surgical hypothalamic lesions. Treatment was analysed based on the neurosurgical strategy of 50 participating neurosurgical centres, the centre size based on the patient load. BMI SDS at diagnosis was similar in patients with or without hypothalamic involvement. Surgical lesions of anterior and posterior hypothalamic areas were associated with higher increase in BMI SDS during 36 months post-diagnosis compared with patients without or only anterior lesion (+1.8 BMISD, P=0.033, +2.1 BMISD; P=0.011), negative impact on QoL in patients with posterior hypothalamic lesions. Surgical strategies varied among the 50 neurosurgical centres (three large-sized, 24 middle-sized and 23 small-sized centres). Patients treated in small-sized centres presented with a higher rate of hypothalamic involvement compared with those treated in the middle- and large-sized centres. Treatment in large-sized centres was less radical, and the rates of complete resection and hypothalamic surgical lesions were lower in large-sized centres than those of the middle- and small-sized centres. However, a multivariable analysis showed that pre-operative hypothalamic involvement was the only independent risk factor for severe obesity (P=0.002). Radical neurosurgical strategies leading to posterior hypothalamic lesions are not recommended due to the potential to exacerbate hypothalamic obesity and impaired QoL. Treatment should be confined to experienced multidisciplinary teams.
    European Journal of Endocrinology 07/2011; 165(1):17-24. · 3.14 Impact Factor
  • Pediatric Blood & Cancer 03/2011; 56(3):503-5. · 2.35 Impact Factor
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    ABSTRACT: Thirty-eight consecutive children treated according to the HIT2000 and HIT91 studies for medulloblastoma who suffered 40 recurrence events were identified from a neuroradiological database. Relapse was associated with younger median age compared with all children treated on HIT2000. Eight patients relapsed with isolated local recurrence. There was no correlation with incomplete surgical removal or violation of the respective treatment protocol. Four patients were younger than 4 years at time of initial presentation and thus were not treated primarily with radiotherapy, suggesting that delayed radiotherapy might be a contributing factor. Meningeal dissemination was present in 32 events; 16 were located in the frontal region, 8 of which were isolated nodular frontal and frontobasal meningeal disease. Circumscribed meningeal recurrences were associated with better overall survival (OS) compared with diffuse, widespread recurrences. Isolated frontobasal meningeal relapses are a well-known phenomenon in medulloblastomas even years after treatment and have been correlated to an underdose of radiation in many literature reports. However, in our patients there was no correlation to possible treatment violations, indicating that inadequate radiation dose to the frontobasal region was unlikely to be a causative factor. Surgical technique varied due to the multicentric nature of our study, so position during surgery was not recognized as a predisposing factor for frontobasal recurrence.
    Journal of Neuro-Oncology 11/2010; 103(3):705-11. · 3.12 Impact Factor
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    ABSTRACT: Poorly differentiated thyroid carcinoma (PDTC) has an unfavorable prognosis. Surgical management is the principal treatment approach. In addition, radioiodine treatment and external beam radiotherapy (EBRT) are given to reduce the risk of local relapse. Despite aggressive therapy, the response to treatment tends to become increasingly poorer over time. The objective of this study was to investigate the induction of apoptosis by EBRT as a function of p53 and bcl-2 protein levels in PDTC. The predictive value of these molecules with respect to treatment efficacy was evaluated. Two different cell lines of PDTC (FTC-133 and ML-1) were irradiated with a dose of 30 Gy. Apoptotic cells were quantified using terminal deoxynucleotidyltransferase-dUTP nick-end labeling staining without irradiation, 48 and 96 hours after irradiation. The protein levels of p53 and bcl-2 were measured simultaneously using flow cytometry and western blotting. The cell cycle distribution was determined. Untreated FTC-133 cells showed a high rate of apoptosis, a high protein level of p53, and a low bcl-2 protein level. Forty-eight hours after irradiation, a slight reduction in apoptotic cells was observed in conjunction with an increase in bcl-2 and p53 protein levels. The slightly reduced fraction of apoptotic cells remained at the same level up to 96 hours after irradiation, whereas the p53 protein level was further downregulated. The cell cycle distribution showed a significant G2/M arrest after 48 hours and recovery 96 hours after irradiation. ML-1 cells did not show any detectable p53 levels and revealed a low rate of apoptosis which significantly increased 48 hours after irradiation. Ninety-six hours after irradiation, a decrease in apoptosis was detectable. The protein level of bcl-2 increased significantly within 48 hours and decreased 96 hours after irradiation. The cell cycle distribution showed a G2/M arrest after 48 hours without a recovery 96 hours after irradiation. The p53 and bcl-2 expression profiles and the observed apoptotic rates of FTC-133 and ML-1 under irradiation are consistent with a more aggressive FTC-133 phenotype. Alterations in p53- and bcl-2 protein levels yield predictive information for EBRT efficacy.
    Thyroid: official journal of the American Thyroid Association 02/2010; 20(2):159-66. · 2.60 Impact Factor
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    ABSTRACT: Controversies surround various treatment variables for patients with childhood craniopharyngioma such as growth hormone (GH) replacement, which some believe can exacerbate recurrence/progression. We prospectively assessed the risk of tumor recurrence/progression in survivors of childhood craniopharyngioma. Multivariable analyses of risk factors (age at diagnosis, degree of resection, irradiation, GH treatment and gender) and descriptive analyses of overall survival (OS) and event-free survival (EFS) rates were performed in 117 patients, recruited prospectively and evaluated after 3 years of follow-up in the German, Austrian and Swiss multicenter trial KRANIOPHARYNGEOM 2000. We observed a 3-year OS of 0.97 and a 3-year EFS of 0.46, indicating high recurrence rates after complete resection (CR) (n = 47; 3-year-EFS: 0.64) and high progression rates after incomplete resection (IR) (n = 64; 3-year EFS: 0.31). The risk of an event decreased by 80% after CR compared to IR (hazard ratio = 0.20; p < 0.001). Irradiation had protective effects on EFS: irradiated patients had an 88% lower risk of recurrence/progression compared to patients without/before irradiation (hazard ratio = 0.12; p < 0.001). GH treatment had no impact on 3-year EFS rates. Tumor recurrences/progressions are frequent and occur early after initial treatment of childhood craniopharyngioma. A radical resection preserving the integrity of hypothalamic structures appears optimal at original diagnosis. Irradiation was efficient in preventing recurrences/progressions. GH treatment had no impact on the low 3-year EFS observed in our study. However, further conclusions on the influence of GH on recurrence rates have to be refined to long-term follow-up studies of patients with childhood craniopharyngioma.
    Hormone Research in Paediatrics 01/2010; 73(3):175-80. · 1.55 Impact Factor
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    ABSTRACT: Several comparison studies have shown the capability of VMAT to achieve similar or better plan quality as IMRT, while reducing the treatment time. The experience of VMAT in a multi vendor environment is limited. We compared the plan quality and performance of VMAT to IMRT and we investigate the effects of varying various user-selectable parameters. IMRT, single arc VMAT and dual arc VMAT were compared for four different head-and-neck tumors. For VMAT, the effect of varying gantry angle spacing and treatment time on the plan quality was investigated. A comparison of monitor units and treatment time was performed. IMRT and dual arc VMAT achieved a similar plan quality, while single arc could not provide an acceptable plan quality. Increasing the number of control points does not improve the plan quality. Dual arc VMAT delivery time is about 30% of IMRT delivery time. Dual arc VMAT is a fast and accurate technique for the treatment of head and neck cancer. It applies similar number of MUs as IMRT, but the treatment time is strongly reduced, maintaining similar or better dose conformity to the PTV and OAR sparing.
    Radiation Oncology 01/2010; 5:110. · 2.11 Impact Factor
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    ABSTRACT: Induction of apoptosis is a widely used strategy for cancer therapy, but evaluating the degree and success of this therapy still poses a problem. Radiolabeled annexin V has been proposed to be a promising candidate for detecting apoptotic cells in tumors following chemotherapy in vivo. In order to see whether radiolabeled annexin V could be a suitable substance for the noninvasive in vivo detection of apoptosis in thyroid tissue and to establish an optimized study protocol, we investigated two poorly differentiated thyroid carcinoma cell lines: ML-1 and FTC-133. Apoptosis was evaluated before as well as 2 and 4 days after in vitro irradiation with 30 Gy X-rays. In this study, binding of FITC- and of (125)I-labeled annexin V was measured in comparison to other apoptosis markers such as Bax, caspase-3 and Fas, which were determined by flow cytometry and Western blot analysis with densitometric evaluation. ML-1 and FTC-133 cells showed a significant increase in annexin V binding 48 h after irradiation. Ninety-six hours after irradiation, the annexin V absorption capability of ML-1 cells was still maximal, while the living fraction of FTC-133 increased significantly. The amount of caspase-3 and Bax was clearly increased 48 h after irradiation and had normalized after 96 h in both cell lines. Fas protein concentrations remained unchanged in ML-1 cells but were significantly enhanced in FTC-133 cells. The binding of FITC- and (125)I-labeled annexin V showed a significant accordance. A reliable evaluation of apoptosis induced by radiotherapy in thyroid tumors was possible 48 h after irradiation, when binding of radiolabeled annexin V is most significantly enhanced. Using two poorly differentiated cell lines of thyroid carcinoma, one may expect to find a nearly similar response to external irradiation. In contrast, the cell lines showed a completely contrary response. However, an individualized study protocol for each type of tumor and probably within each type is necessary.
    Nuclear Medicine and Biology 02/2009; 36(1):89-98. · 2.52 Impact Factor
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    ABSTRACT: The purpose of the study was to investigate the potential of direct machine parameter optimization (DMPO) to achieve parotid sparing without compromising target coverage in IMRT of oropharyngeal cancer as compared to fluence modulation with subsequent leaf sequencing (IM) and forward planned 2-step arc therapy (IMAT). IMRT plans were generated for 10 oropharyngeal cancer patients using DMPO and IM. The resulting dose volume histograms (DVH) were evaluated with regard to compliance with the dose volume objectives (DVO) and plan quality. DMPO met the DVO for the targets better than IM but violated the DVO to the parotids in some cases. DMPO provided better target coverage and dose homogeneity than IM and comparable to IMAT. Dose to the parotids (23Gy) was significantly lower than for IMAT (48Gy), but somewhat higher than for IM (20Gy). Parotid sparing with IM was, however, only achieved at the cost of target coverage and homogeneity. DMPO allows achieving parotid sparing in the treatment of oropharyngeal cancer without compromising target coverage and dose homogeneity in the target as compared to 2-step IMAT. Better overall plan quality can be delivered with less monitor units than with IM.
    Journal of Applied Clinical Medical Physics 01/2009; 10(4):3066. · 0.96 Impact Factor

Publication Stats

243 Citations
101.71 Total Impact Points

Institutions

  • 2008–2013
    • University Hospital Regensburg
      • Klinik und Poliklinik für Strahlentherapie
      Ratisbon, Bavaria, Germany
  • 2007–2011
    • Universität Regensburg
      • Lehrstuhl für Strahlentherapie
      Ratisbon, Bavaria, Germany
  • 2006
    • Klinikum Oldenburg
      Oldenburg, Lower Saxony, Germany
  • 2003–2006
    • University of Wuerzburg
      • Department of Radiation Oncology
      Würzburg, Bavaria, Germany