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Background: Correlating postcardiotomy extracorporeal membrane oxygenation (ECMO) troponin I (TnI) levels and outcomes. Methods: Between January 2006 and August 2010, 34 patients needed postcardiotomy ECMO for low cardiac output. Bailout ECMO was required either after unsuccessful weaning from bypass (n = 17, 50%), postoperatively from prolonged hemodynamic failure (n = 8, 23.5%), or following resuscitation (n = 9, 26.5%). The TnI levels were measured following surgery or resuscitation during 10 days and compared between survivors (group I) and non-survivors (group II). Results: Median support duration was seven days (range: 0-31). Surgery involving hypoplastic aortic arch repair (Norwood palliation; n = 7, 20.6%, or biventricular repair; n = 11, 32.4%) led to most ECMO runs. Successful weaning from ECMO and hospital survival were 76.5% and 50%, respectively. In group I, peak TnI levels were reached by 24 hours postoperatively, comparable to levels in group II (36 ± 34 vs 49 ± 38 ng/mL; P = .98). However, in group II, TnI levels formed a plateau by the second postoperative day, whereas group I showed a steep decline in TnI levels, suggesting myocardial recovery ( P = .028). All patients (n = 4) who reached or maintained peak TnI levels at 48 hours died. On days 8, 9 and 10, TnI levels were significantly higher in group II ( P = .024, .019, and .013, respectively). Conclusions: Postcardiotomy ECMO was most commonly required after aortic arch repair. In the absence of ongoing myocardial insult due to ECMO hardware issues, coronary insufficiency or residual lesions, plateau TnI levels at 48 hours may seem to indicate an unfavorable outcome due to irreversible myocardial damage.

Discrimination measures for continuous time-to-event outcomes have become an important tool in medical decision making. The idea behind discrimination measures is to evaluate the performance of a prediction model by measuring its ability to distinguish between observations having an event and those having no event. Researchers proposed a variety of approaches to estimate discrimination measures from a set of right-censored data. These approaches rely on different regularity assumptions that are needed to ensure consistency of the respective estimators. Typical examples of regularity assumptions include the proportional hazards assumption in Cox regression and the random censoring assumption. Because regularity assumptions are often violated in practice, conducting a sensitivity analysis of the estimators is of considerable interest. The aim of the paper is to analyze and to compare the most popular estimators of discrimination measures for event time outcomes. On the basis of the results of an extensive simulation study and the analysis of molecular data, we investigate the behavior of the estimators in situations where the underlying regularity assumptions do not hold. We show that violations of the regularity assumptions may induce a nonignorable bias and may therefore result in biased medical decision making.

– Aim: To evaluate the influence of reinforcement material on in vitro dental splint rigidity. Materials and Methods: A custom-made artificial model was used. The central incisors simulated ‘injured’ teeth with increased mobility, and the lateral incisors served as ‘uninjured’ teeth with physiologic mobility. The Periotest and Zwick methods were used to assess horizontal and vertical tooth mobility before and after splinting, and relative splint effect (SpErel) was calculated. Teeth 12–22 were splinted using two wire-composite splints (WCS), WCS1 (Dentaflex 0.45 mm), and WCS2 (Strengtheners 0.8 × 1.8 mm) as well as four quartz-fiber splints, QS1 (Quartz Splint UD 1.5 mm), QS2 (Quartz Splint Rope 1.5 mm), QS3 (Quartz Splint Woven 2.5 mm), and QS4 (dry fibers 667 tex). The influence of the splint type was evaluated using anova, Tukey range, and the Dunnett-T3 test (α = 0.05). To test the influence of initial tooth mobility, the t-test was applied (α = 0.05). Results: Reinforcement materials significantly influenced splint rigidity (P

Objectives To evaluate the influence of wire dimension and wire length on the splint rigidity of wire-composite splints in vitro. Materials and methods A custom-made artificial model was used. The central incisors simulated 'injured' teeth with increased mobility, and the lateral incisors and canines served as 'uninjured' teeth with physiological mobility. To assess horizontal and vertical tooth mobility before and after splinting, the Periotest and Zwick methods were applied. Teeth 13-23 were splinted using wire-composite splint 1 (WCS1; Dentaflex 0.45 mm) and wire-composite splint 2 (WCS2; Strengtheners 0.8 × 1.8 mm). Splint length was varied by successively shortening the wire. The influence of wire dimension was tested using t-test and Wilcoxon-Mann-Whitney test with the Bonferroni-Holm procedure (α = 0.05). To test the influence of wire length, anova and Kruskal-Wallis tests as well as Tukey range and Wilcoxon test with Bonferroni-Holm procedure were applied (α = 0.05). Results Wire dimension significantly influenced splint rigidity (P 0.05). Conclusion WCS1 is flexible compared with the more rigid WCS2. The wire length influences the rigidity. To ensure adequate fixation and reduce the risk of enamel damage during splint removal, the splint should include only one 'uninjured' tooth bilaterally.

Objectives The aim of this in vitro study was to investigate a dynamic and static tooth mobility assessment method in terms of reproducibility and correlation. Materials and methods A custom-made artificial model was used. The central incisors simulated 'injured' teeth with increased mobility, and the lateral incisors served as 'uninjured' teeth with physiological mobility. To assess tooth mobility, three consecutively repeated measurements were taken, in the vertical and horizontal dimensions before and after splinting, using the Periotest method as well as the Zwick universal testing machine. Reproducibility of the measurements was tested using anova and the Bonferroni post hoc test (α = 0.05). Correlation was analysed using Spearman's rank correlation (α = 0.05). Results No significant differences were found when comparing the three consecutively taken Periotest values and the vertical Zwick values (P > 0.05). In the horizontal dimension, the first Zwick values differed from the second and third values (P 0.05). Conclusions The Periotest and vertical Zwick values are highly reproducible. The measurements of the two methods do not correlate; therefore, a conversion of Periotest values into metric displacement data is not feasible. The two methods provide different valuable information about tooth mobility. The Periotest method describes the damping characteristics of the periodontal ligament while the Zwick method reveals quantitative metric values.

– Aim: We developed two versions of an artificial model and assessed their suitability for splint rigidity evaluation. These models allowed the simulation of traumatically loosened teeth and the use of the acid-etch technique for splint application. Materials and methods: A straight and half-round arch bar model with bovine tooth facets were manufactured. Using the Periotest method, tooth mobility was evaluated before (PTVpre) and after (PTVpost) splinting. Two types of previously investigated wire-composite splints, WCS1 (Dentaflex 0.45 mm; Dentaurum) and WCS2 (Strengthens 0.8 × 1.8 mm; Dentaurum), were applied (n = 10) to each model. The relative splint effect (SpErel = ΔPTV/PTVpre) was calculated, and the working times for the models and splints were evaluated. Student’s t-test and the Mann–Whitney U-test were employed with Bonferroni correction for multiple hypotheses. Results: When comparing the relative splint effect of the ‘injured’ central incisors between the models within one splint type, differences were only found for tooth 21 (WCS2; P

In many medical applications, data are taken from paired organs or from repeated measurements of the same organ or subject. Subject based as opposed to observation based evaluation of these data results in increased efficiency of the estimation of the misclassification rate. A subject based approach for classification in the generation of bootstrap samples of bagging and bundling methods is analyzed. A simulation model is used to compare the performance of different strategies to create the bootstrap samples which are used to grow individual trees. The proposed approach is compared to linear discriminant analysis, logistic regression, random forests and gradient boosting. Finally, the simulation results are applied to glaucoma diagnosis using both eyes of glaucoma patients and healthy controls. It is demonstrated that the proposed subject based resampling reduces the misclassification rate.

In many medical applications, longitudinal data sets are available. Longitudinal data, as well as observations from paired organs, show a dependency structure which should be respected in the evaluation. Adler et al. (Comput Stat Data Anal 53(3):718–729, 2009) proposed various bootstrapping strategies for ensemble methods based on classification trees for two measurements of paired organs. These strategies have shown to improve the classification performance compared to the traditional approach, where only one observation per subject is used. We extend the methodology to the situation, where an arbitrary number of observations per individual are available and investigate the performance of the proposed methods with bagged classification trees (bagging) and random forests in the situation of longitudinal data. Moreover, we adapt the estimation of classification performance criteria to repeated measurements data. The clinical data set consists of morphological examinations of both eyes of glaucoma patients and healthy controls over a time period of up to 7 years. The performance of our modified classifiers is evaluated by a subject-based leave-one-out bootstrap ROC analysis. Simulation results and results for the glaucoma data set demonstrate that our proposal is an improvement of adhoc strategies and of the use all measurements of each subject or block strategy.

Indices of biotic integrity have become an established tool to quantify the condition of small non-tidal streams and their watersheds. To investigate the effects of watershed characteristics on stream biological condition, we present a new technique for regressing IBIs on watershed-specific explanatory variables. Since IBIs are typically evaluated on an ordinal scale, our method is based on the proportional odds model for ordinal outcomes. To avoid overfitting, we do not use classical maximum likelihood estimation but a component-wise functional gradient boosting approach. Because component-wise gradient boosting has an intrinsic mechanism for variable selection and model choice, determinants of biotic integrity can be identified. In addition, the method offers a relatively simple way to account for spatial correlation in ecological data. An analysis of the Maryland Biological Streams Survey shows that nonlinear effects of predictor variables on stream condition can be quantified while, in addition, accurate predictions of biological condition at unsurveyed locations are obtained.

Objective: The longevity of valved right ventricle to pulmonary artery (RV-PA) conduits is limited due to calcification and degeneration of nonviable structures. Xenografts are commonly used because of the restricted availability of cryopreserved homografts. Tissue-engineered (decellularised) pulmonary valves (TEPVs) were thought to be a valuable alternative to cryopreserved pulmonary homografts due to postoperative seeding with viable autologous vascular endothelial cells. Methods: From July 2007 to December 2008, xenogenous TEPV (Matrix P plus#) were implanted in 16patients in the rightventricular outflowtract for differentindications, relatedto congenitalheart disease.Mean age at operation was 14 11 years, including three patients younger than 1 year. The median conduit size was 22 mm (range: 13—26 mm). Results: The early and late survival rates were 100%. At a median follow-up of 10 months (range: 2—17 months), six patients (38%) had to be re-operated upon due to obstructed grafts. Five of these patients were older than 13 years (range: 13—26 years); one patient was younger than 1 year. On echocardiography before re-operation, mean systolic gradient in the main PA was 66 18 mmHg. In explanted conduits, we found a predominantly peripheral conduit narrowing without leaflet calcification. Histological examination revealed stenosis formation, due to inflammatory infiltration and severely fibrogenic pseudo-intimal reaction. Conclusions: On the basis of our short-term results, the Matrix P plus# de-cellularised tissueengineered pulmonary valve cannot be regarded as an ideal conduit for right ventricular outflow tract reconstruction, as the widespread use of these grafts may increase the possibility of frequent early conduit failures. # 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

Boosting is one of the most important methods for fitting regression models and building prediction rules. A notable feature of boosting is that the technique can be modified such that it includes a built-in mechanism for shrinking coefficient estimates and variable selection. This regularization mechanism makes boosting a suitable method for analyzing data characterized by small sample sizes and large numbers of predictors. We extend the existing methodology by developing a boosting method for prediction functions with multiple components. Such multidimensional functions occur in many types of statistical models, for example in count data models and in models involving outcome variables with a mixture distribution. As will be demonstrated, the new algorithm is suitable for both the estimation of the prediction function and regularization of the estimates. In addition, nuisance parameters can be estimated simultaneously with the prediction function.

Patient empowerment through the Internet is seen as a chance to improve patient-physician communication. Studies on the prevalence of Internet use for health related purposes and on how patients perceive those technologies are still rare. We therefore studied perception of and trends in health related Internet use. As part of a European survey 1.000 German individuals were interviewed using a computer-based telephone interview (CATI: Gabler-Hader-Design, random-digit-dialing, last birthday method) in October 2005. Descriptive statistics and logistic regression models were applied for elaborating characteristics of the health Internet users. Internet use in general (72.3%) and for health related purposes (53.1%) is already quite high. Its importance, relative to other sources of health related information, was rated rather low. Younger citizens and people with paid work used the Internet more often for health related purposes, nevertheless, assessing it as less important for health related purposes than their counterparts. Despite booming of Internet use in Germany, consumers still value and use more the traditional sources of health information/communication with their doctors. Followup studies with a subsequent survey in 2007 will be pursued.

Recent developments in molecular biology have led to the massive discovery of new marker candidates for the prediction of patient survival. To evaluate the predictive value of these markers, statistical tools for measuring the performance of survival models are needed. We consider estimators of discrimination measures, which are a popular approach to evaluate survival predictions in biomarker studies. Estimators of discrimination measures are usually based on regularity assumptions such as the proportional hazards assumption. Based on two sets of molecular data and a simulation study, we show that violations of the regularity assumptions may lead to over-optimistic estimates of prediction accuracy and may therefore result in biased conclusions regarding the clinical utility of new biomarkers. In particular, we demonstrate that biased medical decision making is possible even if statistical checks indicate that all regularity assumptions are satisfied.

Aim To evaluate the influence of adhesive point dimension and splint type on the rigidity of wire-composite splints in vitro. Materials and Methods A custom-made artificial model was used. The two central incisors served as injured teeth (degrees of loosening III and II) and the two lateral incisors as non-injured teeth (physiological mobility). Horizontal and vertical tooth mobilities were investigated before and after splinting with the Periotest® method; the percent change was taken as the relative splint effect. Teeth were splinted with three types of wire-composite splints: Dentaflex (0.45 mm), Strengtheners (0.8 × 1.8 mm), and Dentaflex completely covered with composite. Four adhesive point dimensions (2, 3, 4, and 5 mm) were evaluated. Normal distribution was tested with the Kolmogorov–Smirnov test. Differences were evaluated with the anova and post hoc tests for pair-wise comparisons. Significance level was set at 0.05. Results The adhesive point dimension did not influence splint rigidity, in general ( P = 0.288). Significant effects were found in non-injured teeth with the Dentaflex ( P

Summary Background Preoperative chemoradiotherapy, total mesorectal excision surgery, and adjuvant chemotherapy with fluorouracil is the standard combined modality treatment for rectal cancer. With the aim of improving disease-free survival (DFS), this phase 3 study (CAO/ARO/AIO-04) integrated oxaliplatin into standard treatment. Methods This was a multicentre, open-label, randomised, phase 3 study in patients with histologically proven carcinoma of the rectum with clinically staged T3–4 or any node-positive disease. Between July 25, 2006, and Feb 26, 2010, patients were randomly assigned to two groups: a control group receiving standard fluorouracil-based combined modality treatment, consisting of preoperative radiotherapy of 50·4 Gy plus infusional fluorouracil (1000 mg/m 2 days 1–5 and 29–33), followed by surgery and four cycles of bolus fluorouracil (500 mg/m 2 days 1–5 and 29; fluorouracil group); and an experimental group receiving preoperative radiotherapy of 50·4 Gy plus infusional fluorouracil (250 mg/m 2 days 1–14 and 22–35) and oxaliplatin (50 mg/m 2 days 1, 8, 22, and 29), followed by surgery and eight cycles of adjuvant chemotherapy with oxaliplatin (100 mg/m 2 days 1 and 15), leucovorin (400 mg/m 2 days 1 and 15), and infusional fluorouracil (2400 mg/m 2 days 1–2 and 15–16; fluorouracil plus oxaliplatin group). Randomisation was done with computer-generated block-randomisation codes stratified by centre, clinical T category (cT1–4 vs cT4), and clinical N category (cN0 vs cN1–2) without masking. DFS is the primary endpoint. Secondary endpoints, including toxicity, compliance, and histopathological response are reported here. Safety and compliance analyses included patients as treated, efficacy endpoints were analysed according to the intention-to-treat principle. This study is registered with ClinicalTrials.gov, number NCT00349076. Findings Of the 1265 patients initially enrolled, 1236 were evaluable (613 in the fluorouracil plus oxaliplatin group and 623 in the fluorouracil group). Preoperative grade 3–4 toxic effects occurred in 140 (23%) of 606 patients who actually received fluorouracil and oxaliplatin during chemoradiotherapy and in 127 (20%) of 624 patients who actually received fluorouracil chemoradiotherapy. Grade 3–4 diarrhoea was more common in those who received fluorouracil and oxaliplatin during chemoradiotherapy than in those who received fluorouracil during chemoradiotherapy (73 patients [12%] vs 52 patients [8%]), as was grade 3–4 nausea or vomiting (23 [4%] vs nine [1%]). 516 (85%) of the 606 patients who received fluorouracil and oxaliplatin-based chemoradiotherapy had the full dose of chemotherapy, and 571 (94%) had the full dose of radiotherapy; as did 495 (79%) and 601 (96%) of 624 patients who received fluorouracil-based chemoradiotherapy, respectively. A pathological complete response was achieved in 103 (17%) of 591 patients who underwent surgery in the fluorouracil and oxaliplatin group and in 81 (13%) of 606 patients who underwent surgery in the fluorouracil group (odds ratio 1·40, 95% CI 1·02–1·92; p=0·038). In the fluorouracil and oxaliplatin group, 352 (81%) of 435 patients who began adjuvant chemotherapy completed all cycles (with or without dose reduction), as did 386 (83%) of 463 patients in the fluorouracil group. Interpretation Inclusion of oxaliplatin into modified fluorouracil-based combined modality treatment was feasible and led to more patients achieving a pathological complete response than did standard treatment. Longer follow-up is needed to assess DFS. Funding German Cancer Aid (Deutsche Krebshilfe).

Surgical reconstruction of the right ventricular outflow tract (RVOT) often requires implantation of a valved conduit. A single-centre 10-year experience with the Hancock porcine-valved Dacron conduit was retrospectively assessed.The records of 63 patients who underwent RVOT reconstruction with Hancock conduit implantation between August 2000 and July 2010 were retrospectively reviewed. The median age was 13 years (range, 4 months to 64 years) and the median weight 44 kg (range, 6.5-75 kg). Fifty-one patients (83%) had previous cardiac surgery, and conduit replacement was performed in 31 patients (49%). Patient and conduit survivals with respect to factors precipitating conduit degeneration were analysed. Conduit failure was defined as severe conduit regurgitation or stenosis with a main pulmonary artery systolic gradient over 60 mmHg.Early mortality was 4.8% and not related to conduit failure. Follow-up was complete with a mean duration of 3.5 ± 2.6 years. Patient survival after conduit implantation was 93 [95% confidence interval (CI), 87-100], 90 (95% CI, 81-100) and 85% (95% CI, 74-98) after 1, 3 and 5 years, respectively. Conduit failure occurred in six patients after a median of 5.6 years (range, 2.7-9.0 years). Freedom from conduit failure was 100, 96 (95% CI, 89-100) and 83% (95% CI, 62-100%) after 1, 3 and 5 years, respectively. Mean systolic gradient over the stenotic conduit valve was 87 ± 11 mmHg. Neither RVOT-aneurysm formation nor distal conduit stenosis occurred. Univariate analysis revealed younger age and absent pulmonary valve syndrome as risk factors for conduit failure (P = 0.01 and P0.01). Stepwise logistic regression identified higher white blood cell count at postoperative day 8 as a significant risk factor for conduit failure (odds ratio, 0.7; 95% CI, 0.52-0.89; P0.01).The Hancock conduit is a valuable option for pulmonary valve replacement. It is not associated with RVOT-aneurysm formation or distal conduit stenosis. A persisting perioperative inflammatory reaction may be a predictor for later conduit failure.

The expression of selected microRNAs (miRNAs) known to be involved in the regulation of immune responses was analyzed in 74 patients with relapsing remitting multiple sclerosis (RRMS) and 32 healthy controls. Four miRNAs (miR-326, miR-155, miR-146a, miR-142-3p) were aberrantly expressed in peripheral blood mononuclear cells from RRMS patients compared to controls. Although expression of these selected miRNAs did not differ between treatment-naïve (n = 36) and interferon-beta treated RRMS patients (n = 18), expression of miR-146a and miR-142-3p was significantly lower in glatiramer acetate (GA) treated RRMS patients (n = 20) suggesting that GA, at least in part, restores the expression of deregulated miRNAs in MS.

To evaluate the influence of reinforcement material on in vitro dental splint rigidity. A custom-made artificial model was used. The central incisors simulated 'injured' teeth with increased mobility, and the lateral incisors served as 'uninjured' teeth with physiologic mobility. The Periotest and Zwick methods were used to assess horizontal and vertical tooth mobility before and after splinting, and relative splint effect (SpErel) was calculated. Teeth 12-22 were splinted using two wire-composite splints (WCS), WCS1 (Dentaflex 0.45mm), and WCS2 (Strengtheners 0.8×1.8mm) as well as four quartz-fiber splints, QS1 (Quartz Splint UD 1.5mm), QS2 (Quartz Splint Rope 1.5mm), QS3 (Quartz Splint Woven 2.5mm), and QS4 (dry fibers 667 tex). The influence of the splint type was evaluated using anova, Tukey range, and the Dunnett-T3 test (α=0.05). To test the influence of initial tooth mobility, the t-test was applied (α=0.05). Reinforcement materials significantly influenced splint rigidity (P0.05). The horizontal and vertical SpErel of WCS1 compared with WCS2 and QFSs1-4 was statistically significant (P0.05). Significant differences were found when comparing the horizontal SpErel of WCS2 with WCS1 and QSs1-4 (P0.05). SpErels of the 'injured' and 'uninjured' teeth showed significant differences (P0.05). WCS1 is flexible compared with the more rigid WCS2 and QSs1-4. Initial tooth mobility influences SpErel. The flexible WCS1 can be recommended for splinting dislocation injuries whereas the semi-rigid/rigid WCS2 and QS1-4 can be used for horizontal root fractures and alveolar process fractures. The QS1-4 provide good esthetic outcome.

The aim of this in vitro study was to investigate a dynamic and static tooth mobility assessment method in terms of reproducibility and correlation.A custom-made artificial model was used. The central incisors simulated 'injured' teeth with increased mobility, and the lateral incisors served as 'uninjured' teeth with physiological mobility. To assess tooth mobility, three consecutively repeated measurements were taken, in the vertical and horizontal dimensions before and after splinting, using the Periotest method as well as the Zwick universal testing machine. Reproducibility of the measurements was tested using anova and the Bonferroni post hoc test (α = 0.05). Correlation was analysed using Spearman's rank correlation (α = 0.05).No significant differences were found when comparing the three consecutively taken Periotest values and the vertical Zwick values (P0.05). In the horizontal dimension, the first Zwick values differed from the second and third values (P0.05). Only a few random correlations (P0.05) were found when comparing the two assessment methods. Horizontal and vertical measurements within one method did not correlate (P0.05).The Periotest and vertical Zwick values are highly reproducible. The measurements of the two methods do not correlate; therefore, a conversion of Periotest values into metric displacement data is not feasible. The two methods provide different valuable information about tooth mobility. The Periotest method describes the damping characteristics of the periodontal ligament while the Zwick method reveals quantitative metric values.

Background Improved survival after Norwood stage 1 palliation is giving more patients the opportunity to reach stage 2 palliation; thus, more patients are exposed to the risk of interstage death. Methods A single-center review of patients who underwent stage 1 palliation from January 1998 to December 2007 (n = 58) was performed. Pulmonary blood flow was established either by a modified Blalock-Taussig-shunt (mBTS, n=33) or a right ventricle–to–pulmonary artery conduit (RVPAC, n=25). Results Hospital, interstage, and 1-year survival was not significantly different between groups. However, Kaplan-Meier survival analysis reflected a significantly higher survival probability for RVPAC patients until the age of 120 days (RVAPC, 92% ± 5% [standard error of the mean]; 95% confidence interval, 82 to 100; mBTS, 63% ± 9%; 95% confidence interval, 48 to 82; p = 0.01). During a 1-year follow-up, all 11 nonsurvivors with mBTS died at an age younger than 120 days, including 2 patients with early stage 2 palliation. In contrast, besides 2 early deaths, all RVPAC patients (n = 5) showed later attrition at an age older than 120 days while awaiting stage 2 palliation. Interstage death occurred significantly later among RVPAC patients (RVPAC, 146 ± 60 days versus mBTS, 81 ± 23 days; p = 0.01). After stage 2 palliation, all patients with RVPAC survived, including 7 patients with surgery at an age younger than 120 days. All interstage and late deaths were related to compromising cardiac lesions with no statistical difference between groups. Conclusions After Norwood stage 1 palliation, survival was improved with RVPAC for the first 4 months. However, a loss of the favorable primary outcome was present by delaying stage 2 palliation beyond the age of 120 days. Progressive volume load as a result of conduit regurgitation may play a crucial role for later attrition. Residual lesions should be addressed early to preserve cardiac function.

2040 Background: It is controversial whether concurrent chemoradiotherapy (CRT) with temozolomide is feasible and beneficial in elderly patients with glioblastoma (GBM). Methods: Retrospective analysis of 76 elderly GBM patients (≥ 65 years) treated with concurrent CRT with temozolomide. Factors influencing prognosis and feasibility of CRT were investigated. Results: Median overall survival (mOS) was 11.3 months. Univariate analysis showed a significant difference in mOS for cumulative dose of concurrent temozolomide (optimal cutoff, 2655 mg/m²; 13.9 months for > 2655 mg/m² v 4.9 months for ≤ 2655 mg/m²; P = .0103). Significant independent prognostic parameters in multivariate analysis were: a cumulative dose of concurrent temozolomide > 2655 mg/m² (hazard ratio [HR], 0.41; P = .008), thrombocytopenia grade III/IV (HR, 3.05; P = .034), and biopsy only (HR, 2.10; P = .022). Hematotoxicity was the most common cause of treatment interruption or discontinuation in patients with an insufficient cumulative temo...