Evaluation of Proclarix in the diagnostic work-up of prostate cancer

Objectives

The use of multiparametric magnetic resonance imaging (mpMRI) has been widely adopted in the diagnostic work-up for suspicious prostate cancer (PCa) and is recommended in most current guidelines. However, mpMRI lesions are often indeterminate and/or turn out to be false-positive on prostate biopsy. The aim of this work was to evaluate Proclarix, a biomarker test for the detection of relevant PCa, regarding its diagnostic value in all men before biopsy and in men with indeterminate lesions on mpMRI (PI-RADS 3) during work-up for PCa.

Materials and Methods

Men undergoing mpMRI-targeted and systematic biopsy of the prostate were prospectively enrolled. The Proclarix test was evaluated for the detection accuracy of clinically significant PCa (csPCa) defined as Grade Group ≥ 2 and its association to mpMRI results. Further, Proclarix's performance was also tested when adapted to prostate volume (Proclarix density) and performance compared to PSA density (PSAD).

Results

A total of 150 men with a median age of 65 years and median PSA of 5.8 ng/mL were included in this study. CsPCa was diagnosed in 65 (43%) men. Proclarix was significantly associated with csPCa and higher PI-RADS score (p < 0.001). At the pre-defined cut-off of 10%, Proclarix's sensitivity for csPCa was 94%, specificity 19%, negative predictive value 80% and positive predictive value 47%. Proclarix density showed the highest AUC for the detection of csPCa of 0.77 (95%CI: 0.69-0.85) compared to PSA, PSAD and Proclarix alone. Proclarix was able to identify all six csPCa in men with PI-RADS 3 lesions (n = 28), whereas PSAD missed two out of six. At optimized cut-offs, Proclarix density outperformed PSAD by potentially avoiding 41% of unnecessary biopsies.

Conclusion

Proclarix demonstrates high sensitivity in detecting csPCa but may still result in unnecessary biopsies. However, Proclarix density was able to outperform PSAD and Proclarix and was found to be useful in men with PI-RADS 3 findings by safely avoiding unnecessary biopsies without missing csPCa.

Interobserver agreement on definition of the target volume in stereotactic radiotherapy for pancreatic adenocarcinoma using different imaging modalities

PURPOSE

The aim of this study was to evaluate interobserver agreement (IOA) on target volume definition for pancreatic cancer (PACA) within the Radiosurgery and Stereotactic Radiotherapy Working Group of the German Society of Radiation Oncology (DEGRO) and to identify the influence of imaging modalities on the definition of the target volumes.

METHODS

Two cases of locally advanced PACA and one local recurrence were selected from a large SBRT database. Delineation was based on either a planning 4D CT with or without (w/wo) IV contrast, w/wo PET/CT, and w/wo diagnostic MRI. Novel compared to other studies, a combination of four metrics was used to integrate several aspects of target volume segmentation: the Dice coefficient (DSC), the Hausdorff distance (HD), the probabilistic distance (PBD), and the volumetric similarity (VS).

RESULTS

For all three GTVs, the median DSC was 0.75 (range 0.17-0.95), the median HD 15 (range 3.22-67.11) mm, the median PBD 0.33 (range 0.06-4.86), and the median VS was 0.88 (range 0.31-1). For ITVs and PTVs the results were similar. When comparing the imaging modalities for delineation, the best agreement for the GTV was achieved using PET/CT, and for the ITV and PTV using 4D PET/CT, in treatment position with abdominal compression.

CONCLUSION

Overall, there was good GTV agreement (DSC). Combined metrics appeared to allow a more valid detection of interobserver variation. For SBRT, either 4D PET/CT or 3D PET/CT in treatment position with abdominal compression leads to better agreement and should be considered as a very useful imaging modality for the definition of treatment volumes in pancreatic SBRT. Contouring does not appear to be the weakest link in the treatment planning chain of SBRT for PACA.

What MRI Sequences are Necessary for Automated Neural Network-Based Metastasis Segmentation - An Ablation Study

PURPOSE/OBJECTIVE(S)

Brain metastasis (BM) delineation is a time-consuming process in both daily clinical practice and research. Automated BM segmentation algorithms can be used to assist in this task. Most approaches to brain tumor segmentation, such as algorithms trained on the BraTS challenge, use four magnetic resonance imaging (MRI) sequences as input, making them susceptible to missing or corrupted sequences and increase the number of sequences necessary for MRI RT planning. The goal of this project is to compare neural networks with different combinations of input sequences for the segmentation of the contrast-enhancing metastasis and the surrounding FLAIR hyperintense edema. All models were tested in a multicenter international external test cohort. This allows us to determine which MRI sequences are needed for effective automated segmentations.

MATERIALS/METHODS

In total, we had T1-weighted sequences without (T1) and with contrast enhancement (T1-CE), T2-weighted sequences (T2), and T2 fluid-attenuated inversion recovery (FLAIR) sequences from 339 patients with at least one brain metastasis from seven centers available. Preprocessing yielded co-registered, skull-stripped sequences with an isotropic resolution of 1 millimeter. The contrast-enhancing metastasis as well as the surrounding FLAIR hyperintense edema were manually segmented to create reference labels. A baseline 3D U-Net with all four sequences as well as six additional U-Nets with different clinically plausible combinations (T1-CE; T1; FLAIR; T1-CE+FLAIR; T1-CE+T1+FLAIR; T1-CE+T1) of input sequences were trained on a cohort of 239 patients from two centers and subsequently tested on an external cohort of 100 patients from the remaining five centers.

RESULTS

All models that included T1-CE in their selected sequences showed similar performance for metastasis segmentation with a median Dice similarity coefficient (DSC) of 0.93-0.96. T1-CE alone likewise achieved a performance of 0.96 (IQR 0.93-0.97). The model trained with only FLAIR performed worse (DSC = 0.73, IQR 0.54-0.84). For edema segmentation, models that included both T1-CE and FLAIR performed best (median DSC = 0.93), while the remaining four models without simultaneous inclusion of these two sequences (T1-CE; T1; FLAIR; T1-CE+T1) reached a median DSC of 0.81-0.89.

CONCLUSION

Automatic segmentation of brain metastases with less than four input sequences is feasible with minimal or no loss of quality. A T1-CE-only protocol suffices for metastasis segmentation. In contrast, for edema segmentation, the combination of T1-CE and FLAIR seems to be important. Missing either T1-CE or FLAIR decreases performance. These findings may improve future imaging routines by omitting unnecessary sequences, thus speeding up procedures in daily clinical practice while allowing for optimal neural network-based target definitions.

Stereotactic radiosurgery and radiotherapy for resected brain metastases: current pattern of care in the Radiosurgery and Stereotactic Radiotherapy Working Group of the German Association for Radiation Oncology (DEGRO)

PURPOSE

Preoperative stereotactic radiosurgery (SRS) of brain metastases may achieve similar local control and better leptomeningeal control rates than postoperative fractionated stereotactic radiotherapy (FSRT) in patients treated with elective metastasectomy. To plan a multicentre trial of preoperative SRS compared with postoperative FSRT, a survey of experts was conducted to determine current practice.

METHODS

A survey with 15 questions was distributed to the DEGRO Radiosurgery and Stereotactic Radiotherapy Working Group. Participants were asked under what circumstances they offered SRS, FSRT, partial and/or whole brain radiotherapy before or after resection of a brain metastasis, as well as the feasibility of preoperative stereotactic radiosurgery and neurosurgical resection within 6 days.

RESULTS

Of 25 participants from 24 centres, 22 completed 100% of the questions. 24 respondents were radiation oncologists and 1 was a neurosurgeon. All 24 centres have one or more dedicated radiosurgery platform and all offer postoperative FSRT. Preoperative SRS is offered by 4/24 (16.7%) centres, and 9/24 (37.5%) sometimes recommend single-fraction postoperative SRS. Partial brain irradiation is offered by 8/24 (33.3%) centres and 12/24 (50%) occasionally recommend whole-brain irradiation. Two centres are participating in clinical trials of preoperative SRS. SRS techniques and fractionation varied between centres.

CONCLUSION

All responding centres currently offer postoperative FSRT after brain metastasectomy. Approximately one third offer single-fraction postoperative SRS and four already perform preoperative SRS. With regard to potential co-investigators, 18 were identified for the PREOP‑2 multicentre trial, which will randomise between preoperative SRS and postoperative FSRT.

A novel serum biomarker quintet reveals added prognostic value when combined with standard clinical parameters in prostate cancer patients by predicting biochemical recurrence and adverse pathology

The objective was to determine the prognostic utility of a new biomarker combination in prostate cancer (PCa) patients undergoing Radical Prostatectomy (RP). Serum samples and clinical data of 557 men who underwent RP for PCa with pathological stage (pT) <3 at Martini Clinic (Hamburg, Germany) were used for analysis. Clinical Grade Group and clinical stage was determined using biopsy samples while tumor marker concentrations were measured in serum using immunoassays. The prognostic utility of the proposed marker combination was assessed using Cox proportional hazard regression and Kaplan-Meier analysis. The performance was compared to the Cancer of the Prostate Risk Assessment (CAPRA) score in the overall cohort and in a low-risk patient subset. A multivariable model comprising fibronectin 1, galectin-3-binding protein, lumican, matrix metalloprotease 9, thrombospondin-1 and PSA together with clinical Grade Group (GG) and clinical stage (cT) was created. The proposed model was a significant predictor of biochemical recurrence (BCR) (HR 1.29 per 5 units score, 95%CI 1.20–1.38, p<0.001). The Kaplan-Meier analysis showed that the proposed model had a better prediction for low-risk disease after RP compared to CAPRA (respectively 5.0% vs. 9.1% chance of BCR). In a pre-defined low risk population subset, the risk of BCR using the proposed model was below 5.2% and thus lower when compared to CAPRA = 0–2 (9%), GG<2 (7%) and NCCN = low-risk (6%) subsets. Additionally, the proposed model could significantly (p<0.001) discriminate patients with adverse pathology (AP) events at RP from those without. In conclusion, the proposed model is superior to CAPRA for the prediction of BCR after RP in the overall cohort as well as a in a pre-defined low risk patient population subset. It is also significantly associated with AP at RP.

Improving interinstitutional and intertechnology consistency of pulmonary SBRT by dose prescription to the mean internal target volume dose

Purpose

Dose, fractionation, normalization and the dose profile inside the target volume vary substantially in pulmonary stereotactic body radiotherapy (SBRT) between different institutions and SBRT technologies. Published planning studies have shown large variations of the mean dose in planning target volume (PTV) and gross tumor volume (GTV) or internal target volume (ITV) when dose prescription is performed to the PTV covering isodose. This planning study investigated whether dose prescription to the mean dose of the ITV improves consistency in pulmonary SBRT dose distributions.

Materials and methods

This was a multi-institutional planning study by the German Society of Radiation Oncology (DEGRO) working group Radiosurgery and Stereotactic Radiotherapy. CT images and structures of ITV, PTV and all relevant organs at risk (OAR) for two patients with early stage non-small cell lung cancer (NSCLC) were distributed to all participating institutions. Each institute created a treatment plan with the technique commonly used in the institute for lung SBRT. The specified dose fractionation was 3 × 21.5 Gy normalized to the mean ITV dose. Additional dose objectives for target volumes and OAR were provided.

Results

In all, 52 plans from 25 institutions were included in this analysis: 8 robotic radiosurgery (RRS), 34 intensity-modulated (MOD), and 10 3D-conformal (3D) radiation therapy plans. The distribution of the mean dose in the PTV did not differ significantly between the two patients (median 56.9 Gy vs 56.6 Gy). There was only a small difference between the techniques, with RRS having the lowest mean PTV dose with a median of 55.9 Gy followed by MOD plans with 56.7 Gy and 3D plans with 57.4 Gy having the highest. For the different organs at risk no significant difference between the techniques could be found.

Conclusions

This planning study pointed out that multiparameter dose prescription including normalization on the mean ITV dose in combination with detailed objectives for the PTV and ITV achieve consistent dose distributions for peripheral lung tumors in combination with an ITV concept between different delivery techniques and across institutions.

Supplementary Information

The online version of this article (10.1007/s00066-021-01799-w) contains supplementary material, which is available to authorized users.

[Results of surgical and radiotherapeutic treatment of adenoid cystic carcinoma of the salivary glands]

Surgical treatment in patients with rare adenoid cystic carcinoma (ACC) of the salivary glands is considered to be the state of the art. With respect to an additional radiotherapy there are different approaches regarding the type of radiotherapy and timing. In this study the overall survival and recurrence-free survival in 52 individuals with salivary gland ACC who were treated at the University Hospital in Essen and received irradiation with fast neutrons and photons (mixed beam technique) either A) immediately following surgical treatment or B) only after the appearance of local recurrence were compared. Group A (n = 28, first diagnosis, FD September 1991-September 2009) received adjuvant radiotherapy immediately postoperative, group B (n = 24, FD June 1979-November 2001) underwent primarily surgical tumor resection according to the treatment regimen at that time and were irradiated only on the appearance of a local recurrence. In comparison to group B, patients in group A showed a lower recurrence rate and a significantly longer local relapse-free survival. Group B, however, showed a significantly higher overall survival. The frequency of distant metastasis occurred equally in both groups but the onset of distant metastasis was significantly earlier in group A. In general, overall survival was negatively influenced by distant metastasis. The local recurrence rate was very high after primary surgical treatment only. The immediate adjuvant high-linear energy transfer (LET) radiotherapy reduced the local recurrence rates. Irradiation after the appearance of a recurrence had a positive influence on overall survival. Overall, definitive high-LET radiotherapy in the mixed beam technique enabled high local control rates both primarily postoperative and also locoregional recurrences.

Analytical performance of thrombospondin-1 and cathepsin D immunoassays part of a novel CE-IVD marked test as an aid in the diagnosis of prostate cancer

The Prostate Specific Antigen (PSA) test suffers from low specificity for the diagnosis of Prostate Cancer (PCa). We originally discovered two cancer-related proteins thrombospondin-1 (THBS1) and cathepsin D (CTSD) using a mass-spectrometry-based proteomics approach. The two serum proteins were shown to improve the diagnosis of high-grade PCa. Thus, we developed quantitative ELISAs for the determination of their concentration in human serum. Here we report their analytical performance in terms of limit of detection, specificity, precision, linearity and interferences, which were determined based on CLSI guidelines. Further, we investigated the influence of pre-analytical factors on concentration measurements. For this, blood from 4-6 donors was collected in different tubes and stored at room temperature for different times prior to centrifugation at different centrifugal forces and temperatures. Stability of THBS1 and CTSD under different storage temperatures was also evaluated. Our results show that the assays are specific, linear and sensitive enough to allow measurement of clinical samples. Precision in terms of repeatability and total within-laboratory coefficient of variation (CV) are 5.5% and 8.1% for THBS1 and 4.3% and 7.2% for CTSD, respectively. Relative laboratory-to-laboratory differences were -6.3% for THBS1 and -3% for CTSD. Both THBS1 and CTSD were stable in serum samples, with 80-120% recoveries of concentrations across donors, sample preparation and storage. In conclusion, the ELISAs as part of the novel commercial in vitro diagnostic test Proclarix are suitable for the use in clinical practice. THBS1 and CTSD can be accurately measured for their intended use independent of the lot and laboratory when conditions consistent with routine practice for PSA sampling and storage are used.

The impact of local control on overall survival after stereotactic body radiotherapy for liver and lung metastases from colorectal cancer: a combined analysis of 388 patients with 500 metastases

BACKGROUND

The aim of this analysis was to model the effect of local control (LC) on overall survival (OS) in patients treated with stereotactic body radiotherapy (SBRT) for liver or lung metastases from colorectal cancer.

METHODS

The analysis is based on pooled data from two retrospective SBRT databases for pulmonary and hepatic metastases from 27 centers from Germany and Switzerland. Only patients with metastases from colorectal cancer were considered to avoid histology as a confounding factor. An illness-death model was employed to model the relationship between LC and OS.

RESULTS

Three hundred eighty-eight patients with 500 metastatic lesions (lung n = 209, liver n = 291) were included and analyzed. Median follow-up time for local recurrence assessment was 12.1 months. Ninety-nine patients with 112 lesions experienced local failure. Seventy-one of these patients died after local failure. Median survival time was 27.9 months in all patients and 25.4 months versus 30.6 months in patients with and without local failure after SBRT. The baseline risk of death after local failure exceeds the baseline risk of death without local failure at 10 months indicating better survival with LC.

CONCLUSION

In CRC patients with lung or liver metastases, our findings suggest improved long-term OS by achieving metastatic disease control using SBRT in patients with a projected OS estimate of > 12 months.

Silica particles with a quercetin–R5 peptide conjugate are taken up into HT-29 cells and translocate into the nucleus

Particles generated by biomimetic silica precipitation with a quercetin–R5 peptide enter the nucleus of HT-29 cells without inducing toxicity.

[Necrotizing esophagitis by stress-cardiomyopathy with right ventricular insufficiency]

Acute necrotizing esophagitis ("black esophagus") is defined as complete necrosis of the esophageal mucosa, which typically affects the entire circumference. We report a case of a healthy 62-year-old woman, who became hemodynamically unstable due to stress cardiomyopathy with acute right heart failure. Transfusion-dependent anemia occurred 24 h later and an upper gastrointestinal endoscopy revealed a black discoloured mucosa of the distal esophagus. After hemodynamic stabilization and treatment with proton pump inhibitors and sucralfate, complete healing of the esophageal mucosa was achieved.

Thrombospondin 1 and cathepsin D improve prostate cancer diagnosis by avoiding potentially unnecessary prostate biopsies

Objectives

To investigate and further validate if two novel cancer‐related glycoproteins, discovered by a genetic‐guided proteomics approach, can distinguish benign disease from prostate cancer (PCa) in men with enlarged prostates.

Patients and Methods

A retrospective study was performed that included men with a total prostate‐specific antigen (PSA) concentration of 2.0–10 ng/mL, negative digital rectal examination and enlarged prostate (volume ≥35 mL). Serum samples were collected between 2011 and 2016 at a single centre from 474 men before they underwent prostate biopsy. Serum concentrations of thrombospondin 1 (THBS1) and cathepsin D (CTSD) glycoproteins were combined with the percentage of free PSA to total PSA ratio (%fPSA) to predict any or significant cancer at biopsy.

Results

The multivariable logistic regression model including THBS1, CTSD and %fPSA discriminated among biopsy‐positive and biopsy‐negative patients in the validation set with an area under the curve (AUC) of 0.86 (P < 0.001, 95% confidence interval (CI) 0.82–0.91), while %fPSA alone showed an AUC of 0.64 (P < 0.001, 95% CI 0.57–0.71). At 90% sensitivity for PCa, the specificity of the model was 62%, while %fPSA had a specificity of 23%. For high grade (Gleason score ≥ 7 in prostatectomy specimen) PCa, the specificity was 48% at 90% sensitivity, with an AUC of 0.83, (P < 0.001, 95% CI 0.77 to 0.88). Limitations of the study include the retrospective set‐up and single‐centre cohort.

Conclusions

A model combining two cancer‐related glycoproteins (THBS1 and CTSD) and %fPSA can improve PCa diagnosis and may reduce the number of unnecessary prostate biopsies because of its improved specificity for PCa when compared to %fPSA alone.

Nomogram based overall survival prediction in stereotactic body radiotherapy for oligo-metastatic lung disease

BACKGROUND

Radical local treatment of pulmonary metastases is practiced with increasing frequency due to acknowledgment and better understanding of oligo-metastatic disease. This study aimed to develop a nomogram predicting overall survival (OS) after stereotactic body radiotherapy (SBRT) for pulmonary metastases.

PATIENTS AND METHODS

A multi-institutional database of 670 patients treated with SBRT for pulmonary metastases was used as training cohort. Cox regression analysis with bidirectional variable elimination was performed to identify factors to be included into the nomogram model to predict 2-year OS. The calibration rate of the nomogram was assessed by plotting the actual Kaplan-Meier 2-year OS against the nomogram predicted survival. The nomogram was externally validated using two separate monocentric databases of 145 and 92 patients treated with SBRT for pulmonary metastases.

RESULTS

The median follow up of the trainings cohort was 14.3months, the 2-year and 5-year OS was 52.6% and 23.7%, respectively. Karnofsky performance index, type of the primary tumor, control of the primary tumor, maximum diameter of the largest treated metastasis and number of metastases (1 versus >1) were significant prognostic factors in the Cox model (all p<0.05). The calculated concordance-index for the nomogram was 0.73 (concordance indexes of all prognostic factors between 0.54 and 0.6). Based on the nomogram the training cohort was divided into 4 groups and 2-year OS ranged between 24.2% and 76.1% (predicted OS between 30.2% and 78.4%). The nomogram discriminated between risk groups in the two validation cohorts (concordance index 0.68 and 0.67).

CONCLUSIONS

A nomogram for prediction of OS after SBRT for pulmonary metastases was generated and externally validated. This tool might be helpful for interdisciplinary discussion and evaluation of local and systemic treatment options in the oligo-metastatic setting.

KEY MESSAGE

A nomogram for prediction of overall survival after stereotactic body radiotherapy (SBRT) for pulmonary metastases was developed and externally validated. This tool might be helpful for interdisciplinary discussion and evaluation of local and systemic treatment options in the oligo-metastatic setting.

[Human papillomavirus and squamous cell cancer of the head and neck region : Prognostic, therapeutic and prophylactic implications]

Human papilloma viruses (HPV) are responsible for approximately half of all oropharyngeal squamous cell carcinomas (OPSCC) and incidence rates of HPV-associated OPSCC continue to increase substantially. The defined viral carcinogenesis permits development of specific diagnostic, therapeutic, and prophylactic approaches. Laboratory identification of HPV-associated OPSCC may be achieved by p16(INK4a) immunohistochemistry combined with HPV DNA detection by polymerase chain reaction (PCR) using tumor tissue. Patients with HPV-associated OPSCC have a relatively good prognosis; therefore, the HPV status plays an important role in patient guidance. Due to the relatively favorable prognosis, ongoing studies are evaluating whether less rigorous therapy for HPV-positive patients results in equally good cure rates. The criteria for patient selection are, however, still uncertain. Particularly markers for detection of HPV-positive patients with a high risk of treatment failure are lacking. Besides tumor stage and comorbidities, distinct genomic, epigenetic, and immunologic alterations are prognostically relevant for HPV-associated OPSCC, and might be of predictive value. Furthermore, the characteristic molecular alterations suggest the possibility of novel vigilant and specific therapy approaches. These may be inhibitors of the phosphatidylinositol 3‑kinase (PI3K) pathway, which is frequently activated in HPV-associated OPSCC, and immunotherapeutic methods, e. g., therapeutic vaccination. Although prophylactic HPV vaccinations may also prevent development of HPV-associated OPSCC, foreseeable effects on OPSCC incidence will be low, given the low vaccination rates in Germany. This highlights the fact that interdisciplinary research networks should enhance the necessary activities related to HPV-associated OPSCC.

Dosimetric consequences of pencil beam width variations in scanned beam particle therapy

Scanned ion beam delivery enables the highest degree of target dose conformation attainable in external beam radiotherapy. Nominal pencil beam widths (spot sizes) are recorded during treatment planning system commissioning. Due to changes in the beam-line optics, the actual spot sizes may differ from these commissioning values, leading to differences between planned and delivered dose. The purpose of this study was to analyse the dosimetric consequences of spot size variations in particle therapy treatment plans. For 12 patients with skull base tumours and 12 patients with prostate carcinoma, scanned-beam carbon ion and proton treatment plans were prepared and recomputed simulating spot size changes of (1) ±10% to simulate the typical magnitude of fluctuations, (2) ±25% representing the worst-case scenario and (3) ±50% as a part of a risk analysis in case of fault conditions. The primary effect of the spot size variation was a dose deterioration affecting the target edge: loss of target coverage and broadening of the lateral penumbra (increased spot size) or overdosage and contraction of the lateral penumbra (reduced spot size). For changes ≤25%, the resulting planning target volume mean 95%-isodose line coverage (CI-95%) deterioration was ranging from negligible to moderate. In some cases changes in the dose to adjoining critical structures were observed.

Long survival of primary diffuse leptomeningeal gliomatosis following radiotherapy and temozolomide: case report and literature review

Objective

Primary diffuse leptomeningeal gliomatosis (PDLG) is a rare neoplasm with a short survival time of a few months. there is currently no standardized therapeutic approach for PDLG.

Materials and methods

We report on a 53-year-old male patient who presented with epileptic seizures, gait disturbance, paraparesis and sensory deficits in the dermatomes T8-10.

Results

Magnetic resonance imaging (MRI) revealing numerous spinal and cranial gadolinium-enhancing nodules in the meninges and histopathology led us to diagnose primary diffuse leptomeningeal gliomatosis with WHO grade III astrocytic cells. Consecutively, the patient underwent craniospinal radiotherapy (30 Gy) and 11 sequential cycles of temozolomide. This regimen led to partial tumor regression. Thirteen months later, spinal MRI revealed tumor progression. Second-line chemotherapy with 5 cycles of irinotecan and bevacizumab did not prevent further clinical deterioration. The patient died twenty-two months after diagnosis, being the longest survival time described thus far with respect to PDLG consisting of astrocytic tumor cells.

Conclusions

Radiochemotherapy including temozolomide, as established standard therapy for brain malignant astrocytomas, might be valid as a basic therapeutic strategy for this PDLG subtype.

Continuous glucose monitoring reveals associations of glucose levels with QT interval length

BACKGROUND

QTc interval lengthening during hypoglycemia is discussed as a mechanism linked to sudden death in diabetes patients and the so-called "dead in bed syndrome." Previous research reported a high interindividual variability in the glucose-QTc association. The present study aimed at deriving parameters for direction and strength of the glucose-QTc association on the patient level using combined Holter electrocardiogram (ECG) and continuous glucose monitoring.

METHODS

Twenty type 1 diabetes patients were studied: mean (SD, range) age, 43.6 (10.8, 22-65) years; gender male (n [%]), 10 (50.0%); mean (SD) hemoglobin A1C, 8.5% (1.0%); and impaired hypoglycemia awareness (n [%]), six (30.0%). Continuous interstitial glucose monitoring and Holter ECG monitoring were performed for 48 h. Hierarchical (mixed) regression modeling was used to account for the structure of the data.

RESULTS

Glucose levels during nighttime were negatively associated with QTc interval length if the data structure was accounted for (b [SE] = -0.76 [0.17], P = 0.000). Exploratory regression analysis revealed hypoglycemia awareness as the only predictor of the individual strength of the glucose-QTc association, with the impaired awareness group showing less evidence for an association of low glucose with QTc lengthening.

CONCLUSIONS

Mixed regression allows for deriving parameters for the glucose-QTc association on the patient level. Consistent with previous studies, we found a large interindividual variability in the glucose-QTc association. The finding on impaired hypoglycemia awareness patients has to be interpreted with caution but provides some support for the role of sympathetic activation for the QTc-glucose link.

Comparison between PENELOPE and electron Monte Carlo simulations of electron fields used in the treatment of conjunctival lymphoma

For the treatment of conjunctival lymphoma in the early stages, external beam radiotherapy offers a curative approach. Such treatment requires the use of highly conformed small radiation beams. The beam size is so small that even advanced treatment planning systems have difficulties in calculating dose distributions. One possible approach for optimizing the treatment technique and later performing treatment planning is by means of full Monte Carlo (MC) simulations. In this paper, we compare experimental absorbed dose profiles obtained with a collimator used at the University Hospital Essen, with MC simulations done with the general-purpose radiation transport code PENELOPE. The collimator is also simulated with the hybrid MC code electron Monte Carlo (eMC) implemented in the commercial treatment planning system Eclipse (Varian). The results obtained with PENELOPE have a maximum difference with experimental data of 2.3%, whereas the eMC code differs systematically from the experimental data about 7% in the penumbra tails. We also show that PENELOPE simulations are able to obtain absorbed dose maps with an equivalent statistical uncertainty to the one found with eMC in similar CPU times.

Comparison of adjoint and forward Monte Carlo based treatment planning for a realistic head phantom

BNCT treatment planning can be improved by having the adjoint technique available in the Monte Carlo transport code. In adjoint MC, the simulated particles travel backwards instead of 'forward'. By speeding up the calculations, more beam positions can be investigated and thus a better plan can be composed. In a realistic head phantom with 10 disseminated lesions in the brain, the adjoint method is more favourable than the forward calculations whenever larger beam diameters are applied.

Design of a rotating facility for extracorporal treatment of an explanted liver with disseminated metastases by boron neutron capture therapy with an epithermal neutron beam

In 2001, at the TRIGA reactor of the University of Pavia (Italy), a patient suffering from diffuse liver metastases from an adenocarcinoma of the sigmoid was successfully treated by boron neutron capture therapy (BNCT). The procedure involved boron infusion prior to hepatectomy, irradiation of the explanted liver at the thermal column of the reactor, and subsequent reimplantation. A complete response was observed. This encouraging outcome stimulated the Essen/Petten BNCT group to investigate whether such an extracorporal irradiation could be performed at the BNCT irradiation facility at the HFR Petten (The Netherlands), which has very different irradiation characteristics than the Pavia facility. A computational study has been carried out. A rotating PMMA container with a liver, surrounded by PMMA and graphite, is simulated using the Monte Carlo code MCNP. Due to the rotation and neutron moderation of the PMMA container, the initial epithermal neutron beam provides a nearly homogeneous thermal neutron field in the liver. The main conditions for treatment as reported from the Pavia experiment, i.e. a thermal neutron fluence of 4 x 10(12) +/- 20% cm(-2), can be closely met at the HFR in an acceptable time, which, depending on the defined conditions, is between 140 and 180 min.

Analysis of 10B antitumoral compounds by means of flow-injection into ESI-MS/MS

Boron neutron capture therapy (BNCT) is a promising binary treatment for cancer. BNCT is based on the ability of the nonradioactive isotope (10)B to capture, with a very high probability, thermal neutrons. This nuclear reaction results in two particles (an alpha and a lithium nucleus). The particles have a high biological effectiveness, which is limited in tissue to approximately the diameter of one cell. If the reaction can be limited to a tumor cell, the physical characteristic opens up the possibility to selectively destroy cancer cells, while sparing the surrounding healthy tissue. Quality control of (10)B-containing compounds and their distribution at present are very important, and different analytical methods have been developed, such as time-of-flight secondary ion mass spectrometry (TOF-SIMS), electron energy loss spectrometry (EELS), prompt gamma analysis and inductively coupled plasma-optical emission spectrometry (ICP-OES). These methods allow the analyses of (10)B, but it is not possible to characterize the specific molecular compounds containing (10)B. For this reason, we propose a fast and quantitative method that permits the determination of closo-undecahydro-1-mercaptododecaborate (BSH) and (10)boron-phenylalanine (BPA) and their eventual metabolites. In particular, (10)B-containing compounds are detected by means of flow-injection electrospray tandem mass spectrometry (FI/ESI-MS/MS). This approach allows the identification of Boron compounds, BSH and BPA, using tandem mass spectrometry, and quantitative analysis is also possible (c.v. +/-4.7%; n = 5; linear range 10-10,000 ng/ml). Furthermore, (10)B-containing compounds were detected in actual biological sample (urine and plasma, diluted 10,000- and 1,000-fold, respectively) injecting a small volume (1 microl) of diluted samples.

Advantage and limitations of weighting factors and weighted dose quantities and their units in boron neutron capture therapy

Defining the parameters influencing the biological reaction due to absorbed dose is a continuous topic of research. The main goal of radiobiological research is to translate the measurable dose of ionizing radiation to a quantitative expression of biological effect. Mathematical models based on different biological approaches (e.g., skin reaction, cell culture) provide some estimations that are often misleading and, to some extent, dangerous. Conventional radiotherapy is the simplest case because the primary radiation and secondary radiation are both low linear energy transfer (LET) radiation and have about the same relative biological effectiveness (RBE). Nevertheless, for this one-dose-component case, the dose-effect curves are not linear. In fact, the total absorbed dose and the absorbed dose per fraction as well as the time schedule of the fractionation scheme influence the biological effects. Mathematical models such as the linear-quadratic model can only approximate biological effects. With regard to biological effects, fast neutron therapy is more complex than conventional radiotherapy. Fast neutron beams are always contaminated by gamma rays. As a consequence, biological effects are due to two components, a high-LET component (neutrons) and a low-LET component (photons). A straight transfer of knowledge from conventional radiotherapy to fast neutron therapy is, therefore, not possible: RBE depends on the delivered dose and several other parameters. For dose reporting, the European protocol for fast neutron dosimetry recommends that the total absorbed dose with gamma-ray absorbed dose in brackets is stated. However, boron neutron capture therapy (BNCT) is an even more complex case, because the total absorbed dose is due to four dose components with different LET and RBE. In addition, the terminology and units used by the different BNCT groups is confusing: absorbed dose and weighted dose are both to be stated in grays and are never "photon equivalent." The ICRU/IAEA made proposals, which should be followed by all BNCT groups, to report always the four absorbed dose components, boron dose DB, proton dose Dp, gamma-ray dose Dgamma, and neutron dose Dn, as well as the sum DT of all components, as total absorbed dose, together with the total weighted dose Dw (to be used only for internal purposes, indicating the used weighting factors) at all points of interest and the treatment conditions.