Jürgen Dunst

Plasma osteopontin levels in patients with head and neck cancer and cervix cancer are critically dependent on the choice of ELISA system

BackgroundThe tumor-associated glycoprotein osteopontin (OPN) is discussed as a plasma surrogate marker of tumor hypoxia and as an indicator of the presence of pleural mesothelioma in asbestos-exposed individuals. The clinical introduction of plasma OPN measurements requires the availability of a reliable enzyme-linked immunosorbence assay (ELISA).MethodsWe compared previously described and currently available ELISA systems on 88 archival plasma samples obtained from patients with head and neck or cervix cancer between 20 days before and 171 after the start of radiotherapy.ResultsMedian (range) plasma OPN levels were 667 (148.8–2095) ng/ml and 9.8 (3.5–189.5) ng/ml for a previously described and a newly marketed assay, respectively. Although results for different assays were significantly correlated (r = 0.38, p < 0.05, Spearman rank test), between-assay factors ranged from 2.0 to 217.9 (median 74.6) in individual patients. OPN levels in cervix cancer patients were comparable to those of head and neck cancer patients.ConclusionCommercially available OPN ELISA systems produce different absolute plasma OPN levels, compromising a comparison of individual patient data with published results. However, different assays appear to have a similar capacity to rank patients according to plasma OPN level. A review of literature data suggests that plasma OPN levels measured even with identical ELISA systems can only be compared with caution.

Scoring Systems to Estimate Intracerebral Control and Survival Rates of Patients Irradiated for Brain Metastases

PURPOSEnTo create and validate scoring systems for intracerebral control (IC) and overall survival (OS) of patients irradiated for brain metastases.nnnMETHODS AND MATERIALSnIn this study, 1,797 patients were randomly assigned to the test (n = 1,198) or the validation group (n = 599). Two scoring systems were developed, one for IC and another for OS. The scores included prognostic factors found significant on multivariate analyses. Age, performance status, extracerebral metastases, interval tumor diagnosis to RT, and number of brain metastases were associated with OS. Tumor type, performance status, interval, and number of brain metastases were associated with IC. The score for each factor was determined by dividing the 6-month IC or OS rate (given in percent) by 10. The total score represented the sum of the scores for each factor. The score groups of the test group were compared with the corresponding score groups of the validation group.nnnRESULTSnIn the test group, 6-month IC rates were 17% for 14-18 points, 49% for 19-23 points, and 77% for 24-27 points (p < 0.0001). IC rates in the validation group were 19%, 52%, and 77%, respectively (p < 0.0001). In the test group, 6-month OS rates were 9% for 15-19 points, 41% for 20-25 points, and 78% for 26-30 points (p < 0.0001). OS rates in the validation group were 7%, 39%, and 79%, respectively (p < 0.0001).nnnCONCLUSIONSnPatients irradiated for brain metastases can be given scores to estimate OS and IC. IC and OS rates of the validation group were similar to the test group demonstrating the validity and reproducibility of both scores.

Late sequelae in oncology

Increasing survival figures and the use of more intense combined treatment regimens in modern oncology have raised the problem of late therapeutic sequelae in long-term survivors after cancer. Recent scientific approaches to late sequelae concentrate on the evaluation of subclinical changes with sophisticated functional measurements and experimental investigation of the underlying pathophysiological mechanisms. The object of this book is to bring together recent clinical and experimental data from different medical disciplines to give an overview of the most relevant problems of late sequelae. In clinical practice the book can be used to estimate risks, select diagnostic methods, and estimate the prognosis of late sequelae.

Immunohistochemical Detection of HIF-1α and CAIX in Advanced Head-and-Neck Cancer

Background:Tumor hypoxia has an impact on the outcome of cancer patients treated with radiotherapy. The validity of endogenous markers such as hypoxia-inducible factor-1α (HIF-1α) and carbonic anhydrase isozyme IX (CAIX) to detect therapeutically relevant levels of hypoxia within tumors is controversially discussed. Furthermore, the association of these hypoxia markers with tumor markers or tumor oxygenation parameters is of importance for understanding the relationship between the different factors.Patients and Methods:Tumor tissue sections of 34 patients with advanced head-and-neck cancer treated with radio(chemo)therapy were assessed by immunohistochemistry for the expression of HIF-1α and CAIX. The relationships of both markers with tumor oxygenation parameters, molecular factors like P53, OPN, VEGF, VHL, survivin, and Ki67 levels, and clinical parameters were studied.Results:Bivariate analysis showed a significant correlation of HIF-1α expression with high P53 and high OPN expression, high serum VEGF levels, and low VHL and low Ki67 expression. The CAIX expression was inversely correlated with pH value and directly correlated with T-stage. However, no correlation was found between HIF-1α and CAIX expression.Neither in a univariate Cox proportional hazard regression nor in a Kaplan-Meier analysis did expression of HIF-1α or CAIX have a significant impact on clinical outcome. However, in a Kaplan-Meier analysis, the combination of both factors showed that patients with intratumoral overexpression of either HIF-1α or CAIX or both markers died on average 2 years earlier than patients whose tumors had low expression of both factors (p < 0.05).Conclusion:Expression of HIF-1α and CAIX was correlated with different tumor parameters. Only combined HIF-1α and CAIX expression was significantly predictive of patients overall survival.Hintergrund:Hypoxie in Tumoren hat einen Einfluss auf die Prognose von Tumorpatienten, die eine Strahlentherapie erhielten. Der Einsatz von endogenen Markern wie hypoxieinduzierbarem Faktor-1α (HIF-1α) und Carboanhydrase-Isoenzym IX (CAIX) zur Identifizierung therapierelevanter hypoxischer Tumorbereiche wird jedoch kontrovers diskutiert. Die Untersuchung der Assoziation von Tumormarkern und tumorrelevanten Oxygenierungsparametern ist deshalb von wesentlicher Bedeutung für das Verständnis der Beziehung dieser biologischen Indikation.Patienten und Methodik:An Tumorgewebeschnitten von 34 Patienten mit radio(chemo)therapierten fortgeschrittenen Kopf-Hals-Tumoren wurde immunhistochemisch die Expression von HIF-1α und CAIX untersucht. Die Expression beider Marker wurde mit Tumoroxygenierungsparametern, der Expression molekularer Faktoren wie P53, OPN, VEGF, VHL, Survivin und Ki67 sowie klinischen Parametern in Beziehung gesetzt.Ergebnisse:Bivariate Analysen zeigten eine signifikante Korrelation zwischen einer HIF-1α-Expression und einer hohen P53- und OPN-Expression, einem hohen Serum-VEGF-Gehalt sowie einer geringeren VHL- und Ki67-Expression. Eine hohe CAIX-Expression korrelierte invers mit dem pH-Wert und direkt mit dem T-Stadium. Zwischen der HIF-1α- und CAIX-Expression wurde keine Korrelation nachgewiesen.Mittels univariater Cox-Regressions- bzw. Kaplan-Meier-Analyse zeigte weder die HIF-1α- noch die CAIX-Expression einen signifikanten Einfluss auf das Überleben. Die Kombination der beiden Faktoren ergab dagegen in der Kaplan-Meier-Analyse, dass Patienten mit intratumoraler Überexpression von HIF-1α oder CAIX oder beiden Markern durchschnittlich 2 Jahre früher verstarben als Patienten, deren Tumoren eine geringe Expression beider Faktoren aufwiesen (p < 0,05).Schlussfolgerung:Die Expression von HIF-1α und CAIX korrelierte mit verschiedenen Tumorparametern. Erst die Kombination der Marker HIF-1α und CAIX zeigte einen signifikanten prädiktiven Einfluss auf das Gesamtüberleben von Patienten mit Kopf-Hals-Tumoren nach einer Radio(chemo)therapie.

Ionizing radiation induces a motile phenotype in human carcinoma cells in vitro through hyperactivation of the TGF-beta signaling pathway

Radiotherapy, a major treatment modality against cancer, can lead to secondary malignancies but it is uncertain as to whether tumor cells that survive ionizing radiation (IR) treatment undergo epithelial–mesenchymal transition (EMT) and eventually become invasive or metastatic. Here, we have tested the hypothesis that the application of IR (10xa0MeV photon beams, 2–20xa0Gy) to lung and pancreatic carcinoma cells induces a migratory/invasive phenotype in these cells by hyperactivation of TGF-β and/or activin signaling. In accordance with this assumption, IR induced gene expression patterns and migratory responses consistent with an EMT phenotype. Moreover, in A549 cells, IR triggered the synthesis and secretion of both TGF-β1 and activin A as well as activation of intracellular TGF-β/activin signaling as evidenced by Smad phosphorylation and transcriptional activation of a TGF-β-responsive reporter gene. These responses were sensitive to SB431542, an inhibitor of type I receptors for TGF-β and activin. Likewise, specific antibody-mediated neutralization of soluble TGF-β, or dominant-negative inhibition of the TGF-β receptors, but not the activin type I receptor, alleviated IR-induced cell migration. Moreover, the TGF-β-specific approaches also blocked IR-dependent TGF-β1 secretion, Smad phosphorylation, and reporter gene activity, collectively indicating that autocrine production of TGF-β(s) and subsequent activation of TGF-β rather than activin signaling drives these changes. IR strongly sensitized cells to further increase their migration in response to recombinant TGF-β1 and this was accompanied by upregulation of TGF-β receptor expression. Our data raise the possibility that hyperactivation of TGF-β signaling during radiotherapy contributes to EMT-associated changes like metastasis, cancer stem cell formation and chemoresistance of tumor cells.

Inverse treatment planning for spinal robotic radiosurgery: an international multi-institutional benchmark trial

Stereotactic radiosurgery (SRS) is the accurate, conformal delivery of high-dose radiation to well-defined targets while minimizing normal structure doses via steep dose gradients. While inverse treatment planning (ITP) with computerized optimization algorithms are routine, many aspects of the planning process remain user-dependent. We performed an international, multi-institutional benchmark trial to study planning variability and to analyze preferable ITP practice for spinal robotic radiosurgery. 10 SRS treatment plans were generated for a complex-shaped spinal metastasis with 21 Gy in 3 fractions and tight constraints for spinal cord (V14Gy<2u2009cc, V18Gy<0.1u2009cc) and target (coverage >95%). The resulting plans were rated on a scale from 1 to 4 (excellent-poor) in five categories (constraint compliance, optimization goals, low-dose regions, ITP complexity, and clinical acceptability) by a blinded review panel. Additionally, the plans were mathematically rated based on plan indices (critical structure and target doses, conformity, monitor units, normal tissue complication probability, and treatment time) and compared to the human rankings. The treatment plans and the reviewers rankings varied substantially among the participating centers. The average mean overall rank was 2.4 (1.2-4.0) and 8/10 plans were rated excellent in at least one category by at least one reviewer. The mathematical rankings agreed with the mean overall human rankings in 9/10 cases pointing toward the possibility for sole mathematical plan quality comparison. The final rankings revealed that a plan with a well-balanced trade-off among all planning objectives was preferred for treatment by most participants, reviewers, and the mathematical ranking system. Furthermore, this plan was generated with simple planning techniques. Our multi-institutional planning study found wide variability in ITP approaches for spinal robotic radiosurgery. The participants, reviewers, and mathematical match on preferable treatment plans and ITP techniques indicate that agreement on treatment planning and plan quality can be reached for spinal robotic radiosurgery. PACS number(s): 87.55.de.Stereotactic radiosurgery (SRS) is the accurate, conformal delivery of high‐dose radiation to well‐defined targets while minimizing normal structure doses via steep dose gradients. While inverse treatment planning (ITP) with computerized optimization algorithms are routine, many aspects of the planning process remain user‐dependent. We performed an international, multi‐institutional benchmark trial to study planning variability and to analyze preferable ITP practice for spinal robotic radiosurgery. 10 SRS treatment plans were generated for a complex‐shaped spinal metastasis with 21 Gy in 3 fractions and tight constraints for spinal cord (V14Gy<2u2009cc, V18Gy<0.1u2009cc) and target (coverage >95%). The resulting plans were rated on a scale from 1 to 4 (excellent‐poor) in five categories (constraint compliance, optimization goals, low‐dose regions, ITP complexity, and clinical acceptability) by a blinded review panel. Additionally, the plans were mathematically rated based on plan indices (critical structure and target doses, conformity, monitor units, normal tissue complication probability, and treatment time) and compared to the human rankings. The treatment plans and the reviewers rankings varied substantially among the participating centers. The average mean overall rank was 2.4 (1.2‐4.0) and 8/10 plans were rated excellent in at least one category by at least one reviewer. The mathematical rankings agreed with the mean overall human rankings in 9/10 cases pointing toward the possibility for sole mathematical plan quality comparison. The final rankings revealed that a plan with a well‐balanced trade‐off among all planning objectives was preferred for treatment by most participants, reviewers, and the mathematical ranking system. Furthermore, this plan was generated with simple planning techniques. Our multi‐institutional planning study found wide variability in ITP approaches for spinal robotic radiosurgery. The participants, reviewers, and mathematical match on preferable treatment plans and ITP techniques indicate that agreement on treatment planning and plan quality can be reached for spinal robotic radiosurgery. PACS number(s): 87.55.de

A liquid fluorescence dosimeter for proton dosimetry

The pyromellitic acid (benzene-1,2,4,5-tetracrboxylic acid) dosimeter is a liquid, nearly tissue equivalent detector (the density of the solution is 1.000u200956 g cm⁻³). This acid fluoresces after exposure to proton radiation, if excited with light. The detector was exposed to proton doses of 1.0-10.0 Gy (energies: 138 and 160 MeV). The correlation between fluorescence intensity and delivered energy dose is one to one and linear, whereby the deviation from the linear behavior for all measured values is less than 1%. Variations of the dose rate between 2.4 and 6.0 Gy s⁻¹ had no influence on the correlation between dose and fluorescence. The quenching of the pyromellitic acid detector amounts to about 22% for 138 MeV protons in the Bragg peak. For the period of 1-26 days after exposure, an increase in fluorescence intensity of the exposed solutions (5.0 Gy) was noticed, which corresponds to a daily data drift averaging 0.91% if the solution is stored in the dark at 4 °C. Non-exposed solutions showed no change of the control value.

Factors influencing heterogeneity of radiation-induced DNA-damage measured by the alkaline comet assay

BackgroundTo investigate whether different conditions of DNA structure and radiation treatment could modify heterogeneity of response. Additionally to study variance as a potential parameter of heterogeneity for radiosensitivity testing.MethodsTwo-hundred leukocytes per sample of healthy donors were split into four groups. I: Intact chromatin structure; II: Nucleoids of histone-depleted DNA; III: Nucleoids of histone-depleted DNA with 90u2009mM DMSO as antioxidant. Response to single (I-III) and twice (IV) irradiation with 4u2009Gy and repair kinetics were evaluated using %Tail-DNA. Heterogeneity of DNA damage was determined by calculation of variance of DNA-damage (V) and mean variance (Mvar), mutual comparisons were done by one-way analysis of variance (ANOVA).ResultsHeterogeneity of initial DNA-damage (I, 0u2009min repair) increased without histones (II). Absence of histones was balanced by addition of antioxidants (III). Repair reduced heterogeneity of all samples (with and without irradiation). However double irradiation plus repair led to a higher level of heterogeneity distinguishable from single irradiation and repair in intact cells. Increase of mean DNA damage was associated with a similarly elevated variance of DNA damage (ru2009=u2009+0.88).ConclusionsHeterogeneity of DNA-damage can be modified by histone level, antioxidant concentration, repair and radiation dose and was positively correlated with DNA damage. Experimental conditions might be optimized by reducing scatter of comet assay data by repair and antioxidants, potentially allowing better discrimination of small differences. Amount of heterogeneity measured by variance might be an additional useful parameter to characterize radiosensitivity.

Treatment Planning Considerations for Robotic Guided Cardiac Radiosurgery for Atrial Fibrillation

Purpose Robotic guided stereotactic radiosurgery has recently been investigated for the treatment of atrial fibrillation (AF). Before moving into human treatments, multiple implications for treatment planning given a potential target tracking approach have to be considered. Materials & Methods Theoretical AF radiosurgery treatment plans for twenty-four patients were generated for baseline comparison. Eighteen patients were investigated under ideal tracking conditions, twelve patients under regional dose rate (RDR = applied dose over a certain time window) optimized conditions (beam delivery sequence sorting according to regional beam targeting), four patients under ultrasound tracking conditions (beam block of the ultrasound probe) and four patients with temporary single fiducial tracking conditions (differential surrogate-to-target respiratory and cardiac motion). Results With currently known guidelines on dose limitations of critical structures, treatment planning for AF radiosurgery with 25 Gy under ideal tracking conditions with a 3 mm safety margin may only be feasible in less than 40% of the patients due to the unfavorable esophagus and bronchial tree location relative to the left atrial antrum (target area). Beam delivery sequence sorting showed a large increase in RDR coverage (% of voxels having a larger dose rate for a given time window) of 10.8-92.4% (median, 38.0%) for a 40-50 min time window, which may be significant for non-malignant targets. For ultrasound tracking, blocking beams through the ultrasound probe was found to have no visible impact on plan quality given previous optimal ultrasound window estimation for the planning CT. For fiducial tracking in the right atrial septum, the differential motion may reduce target coverage by up to -24.9% which could be reduced to a median of -0.8% (maximum, -12.0%) by using 4D dose optimization. The cardiac motion was also found to have an impact on the dose distribution, at the anterior left atrial wall; however, the results need to be verified. Conclusion Robotic AF radiosurgery with 25 Gy may be feasible in a subgroup of patients under ideal tracking conditions. Ultrasound tracking was found to have the lowest impact on treatment planning and given its real-time imaging capability should be considered for AF robotic radiosurgery. Nevertheless, advanced treatment planning using RDR or 4D respiratory and cardiac dose optimization may be still advised despite using ideal tracking methods.

Concurrent chemoradiation of metastases with capecitabine and oxaliplatin and 3D-CRT in patients with oligometastatic colorectal cancer: results of a phase I study

BackgroundLocal control appears to be an important treatment aim in patients with limited metastases (oligometastases) of colorectal cancer (CRC). Those patients show a favourable prognosis, if - in addition to the local effective treatment - an occurrence of new metastases may also be postponed by effective systemic therapy. The purpose of this dose escalation phase I study was to establish the efficacy of local radiotherapy (RT) of oligometastatic CRC with a concurrent standard chemotherapy regimen.MethodsPatients with first-, second- or third-line therapy of oligometastatic CRC (1–3 metastases or local recurrence plus max. 2 metastases) received capecitabine (825u2009mg/m2/d BID d 1–14; 22–35) and oxaliplatin (50u2009mg/m2 d 1, 8, 22, 29). 3D-conformal RT of all metastatic lesions was delivered in 2.0u2009Gy up to 36u2009Gy to 50u2009Gy (3 dose levels). Primary endpoint was the maximal tolerable dose (MTD) of RT defined as the level at which two or more of six patients experienced dose-limiting toxicity (DLT).ResultsBetween 09/2004 and 08/2007, 9 patients (7 male, 2 female, 50–74u2009years) were enrolled, 6 patients treated at dose level 1 (36u2009Gy), 3 patients at dose level 2 (44u2009Gy). 1 patient from the first cohort experienced DLT (oxaliplatin-related hypersensitivity reaction). No radiation-induced DLT occurred. 6/9 patients achieved objective response (partial remission). One year after initiation, all patients were alive, 6 patients survived (16 to 54u2009months) patients died of tumor progression (14 to 23u2009months). The phase II part of the trial had to be closed due to recruitment failure.ConclusionsLocal 3D-CRT to metastatic lesions in addition to standard chemotherapy was feasible, DLT was not documented. 3/9 patients survived for a period of 3.5 to 4.4u2009years (time at the last evaluation). Radiotherapy of metastatic lesions should be incorporated into subsequent trials.