Evaluating the impact of a rigid and a deformable registration method of pre-treatment images for hypoxia-based dose painting

PURPOSE

To assess the impact of rigid and deformable image registration methods (RIR, DIR) on the outcome of a hypoxia-based dose painting strategy.

MATERIALS AND METHODS

Thirty head and neck cancer patients were imaged with [18F]FMISO-PET/CT before radiotherapy. [18F]FMISO-PET/CT images were registered to the planning-CT by RIR or DIR. The [18F]FMISO uptake was converted into oxygen partial pressure (pO2) maps. Hypoxic Target Volumes were contoured on pO2 maps for the deformed (HTVdef) and non-deformed (HTV) cases. A dose escalation strategy by contours, aiming at 95 % tumour control probability (TCP), was applied. HTVs were characterised based on geometry-related metrics, the underlying pO2 distribution, and the dose boost level. A dosimetric and radiobiological evaluation of selected treatment plans made considering RIR and DIR was performed. Moreover, the TCP of the RIR dose distribution was evaluated when considering the deformed [18F]FMISO-PET image as an indicator of the actual target radiosensitivity to determine the potential impact of an unalignment.

RESULTS

Statistically significant differences were found between HTV and HTVdef for volume-based metrics and underlying pO2 distribution. Eight out of nine treatment plans for HTV and HTVdef showed differences on the level 10 %/3 mm on a gamma analysis. The TCP difference, however, between RIR and the case when the RIR dose distribution was used with the deformed radiosensitivity map was below 2 pp.

CONCLUSIONS

Although the choice of the CTplan-to-PET registration method pre-treatment impacts the HTV localisation and morphology and the corresponding dose distribution, it negligibly affects the TCP in the proposed dose escalation strategy by contours.

TRIB1 confers therapeutic resistance in GBM cells by activating the ERK and Akt pathways

GBM (Glioblastoma) is the most lethal CNS (Central nervous system) tumor in adults, which inevitably develops resistance to standard treatments leading to recurrence and mortality. TRIB1 is a serine/threonine pseudokinase which functions as a scaffold platform that initiates degradation of its substrates like C/EBPα through the ubiquitin proteasome system and also activates MEK and Akt signaling. We found that increased TRIB1 gene expression associated with worse overall survival of GBM patients across multiple cohorts. Importantly, overexpression of TRIB1 decreased RT/TMZ (radiation therapy/temozolomide)-induced apoptosis in patient derived GBM cell lines in vitro. TRIB1 directly bound to MEK and Akt and increased ERK and Akt phosphorylation/activation. We also found that TRIB1 protein expression was maximal during G2/M transition of cell cycle in GBM cells. Furthermore, TRIB1 bound directly to HDAC1 and p53. Importantly, mice bearing TRIB1 overexpressing tumors had worse overall survival. Collectively, these data suggest that TRIB1 induces resistance of GBM cells to RT/TMZ treatments by activating the cell proliferation and survival pathways thus providing an opportunity for developing new targeted therapeutics.

The Judicious Use of Stereotactic Ablative Radiotherapy in the Primary Management of Localized Renal Cell Carcinoma

Localized renal cell carcinoma is primarily managed surgically, but this disease commonly presents in highly comorbid patients who are poor operative candidates. Less invasive techniques, such as cryoablation and radiofrequency ablation, are effective, but require percutaneous or laparoscopic access, while generally being limited to cT1a tumors without proximity to the renal pelvis or ureter. Active surveillance is another management option for small renal masses, but many patients desire treatment or are poor candidates for active surveillance. For poor surgical candidates, a growing body of evidence supports stereotactic ablative radiotherapy (SABR) as a safe and effective non-invasive treatment modality. For example, a recent multi-institution individual patient data meta-analysis of 190 patients managed with SABR estimated a 5.5% five-year cumulative incidence of local failure with one patient experiencing grade 4 toxicity, and no other grade ≥3 toxic events. Here, we discuss the recent developments in SABR for the management of localized renal cell carcinoma, highlighting key concepts of appropriate patient selection, treatment design, treatment delivery, and response assessment.

Integration of radiation oncology teaching in medical studies by German medical faculties due to the new licensing regulations : An overview and recommendations of the consortium academic radiation oncology of the German Society for Radiation Oncology (DEGRO)

The new Medical Licensing Regulations 2025 (Ärztliche Approbationsordnung, ÄApprO) will soon be passed by the Federal Council (Bundesrat) and will be implemented step by step by the individual faculties in the coming months. The further development of medical studies essentially involves an orientation from fact-based to competence-based learning and focuses on practical, longitudinal and interdisciplinary training. Radiation oncology and radiation therapy are important components of therapeutic oncology and are of great importance for public health, both clinically and epidemiologically, and therefore should be given appropriate attention in medical education. This report is based on a recent survey on the current state of radiation therapy teaching at university hospitals in Germany as well as the contents of the National Competence Based Learning Objectives Catalogue for Medicine 2.0 (Nationaler Kompetenzbasierter Lernzielkatalog Medizin 2.0, NKLM) and the closely related Subject Catalogue (Gegenstandskatalog, GK) of the Institute for Medical and Pharmaceutical Examination Questions (Institut für Medizinische und Pharmazeutische Prüfungsfragen, IMPP). The current recommendations of the German Society for Radiation Oncology (Deutsche Gesellschaft für Radioonkologie, DEGRO) regarding topics, scope and rationale for the establishment of radiation oncology teaching at the respective faculties are also included.

Recent advances of PET imaging in clinical radiation oncology

Radiotherapy and radiation oncology play a key role in the clinical management of patients suffering from oncological diseases. In clinical routine, anatomic imaging such as contrast-enhanced CT and MRI are widely available and are usually used to improve the target volume delineation for subsequent radiotherapy. Moreover, these modalities are also used for treatment monitoring after radiotherapy. However, some diagnostic questions cannot be sufficiently addressed by the mere use standard morphological imaging. Therefore, positron emission tomography (PET) imaging gains increasing clinical significance in the management of oncological patients undergoing radiotherapy, as PET allows the visualization and quantification of tumoral features on a molecular level beyond the mere morphological extent shown by conventional imaging, such as tumor metabolism or receptor expression. The tumor metabolism or receptor expression information derived from PET can be used as tool for visualization of tumor extent, for assessing response during and after therapy, for prediction of patterns of failure and for definition of the volume in need of dose-escalation. This review focuses on recent and current advances of PET imaging within the field of clinical radiotherapy / radiation oncology in several oncological entities (neuro-oncology, head & neck cancer, lung cancer, gastrointestinal tumors and prostate cancer) with particular emphasis on radiotherapy planning, response assessment after radiotherapy and prognostication.

Combined radiotherapy and concurrent tumor treating fields (TTFields) for glioblastoma: Dosimetric consequences on non-coplanar IMRT as initial results from a phase I trial

Background

Glioblastoma is a rapidly proliferating tumor. Patients bear an inferior prognosis with a median survival time of 14-16 months. Proliferation and repopulation are a major resistance promoting factor for conventionally fractionated radiotherapy. Tumor-Treating-Fields (TTFields) are an antimitotic modality applying low-intensity (1-3 V/cm), intermediate-frequency (100-300 kHz) alternating electric-fields. More recently interference of TTFields with DNA-damage-repair and synergistic effects with radiotherapy were reported in the preclinical setting. This study aims at examining the dosimetric consequences of TTFields applied during the course of radiochemotherapy.

Methods

Cone-beam-computed-tomography (CBCT)-data from the first seven patients of the PriCoTTF-phase-I-trial were used in a predefined way for dosimetric verification and dose-accumulation of the non-coplanar-intensity-modulated-radiotherapy (IMRT)-treatment-plans as well as geometric analysis of the transducer-arrays by which TTFields are applied throughout the course of treatment. Transducer-array-position and contours were obtained from the low-dose CBCT’s routinely made for image-guidance. Material-composition of the electrodes was determined and a respective Hounsfield-unit was assigned to the electrodes. After 6D-fusion with the planning-CT, the dose-distribution was recalculated using a Boltzmann-equation-solver (Acuros XB) and a Monte-Carlo-dose-calculation-engine.

Results

Overdosage in the scalp in comparison to the treatment plan without electrodes stayed below 8.5% of the prescribed dose in the first 2 mm below and also in deeper layers outside 1cm² at highest dose as obtained from dose-volume-histogram comparisons. In the clinical target volume (CTV), underdosage was limited to 2.0% due to dose attenuation by the electrodes in terms of D95 and the effective-uniform-dose. Principal-component-analysis (PCA) showed that the first principal-position-component of the variation of repeated array-placement in the direction of the largest variations and the perpendicular second-component spanning a tangential plane on the skull had a standard deviation of 1.06 cm, 1.23 cm, 0.96 cm, and 1.11 cm for the frontal, occipital, left and right arrays for the first and 0.70 cm, 0.71 cm, 0.79 cm, and 0.68 cm, respectively for the second-principal-component. The variations did not differ from patient-to-patient (p > 0.8, Kruskal-Wallis-tests). This motion led to a diminution of the dosimetric effects of the electrodes.

Conclusion

From a dosimetric point of view, dose deviations in the CTV due to transducer-arrays were not clinically significant in the first 7 patients and confirmed feasibility of combined adjuvant radiochemotherapy and concurrent TTFields.

PriCoTTF Trial: A phase I/II trial of TTFields prior and concomitant to radiotherapy in newly diagnosed glioblastoma.

DRKS-ID: DRKS00016667.

Date of Registration in DRKS: 2019/02/26.

Investigator Sponsored/Initiated Trial (IST/IIT): yes.

Ethics Approval/Approval of the Ethics Committee: Approved.

(leading) Ethics Committee Nr.: 18–8316-MF, Ethik-Kommission der Medizinischen.

Fakultät der Universität Duisburg-Essen.

EUDAMED-No. (for studies acc. to Medical Devices act): CIV-18-08-025247.

Influence of localization of PSMA-positive oligo-metastases on efficacy of metastasis-directed external-beam radiotherapy-a multicenter retrospective study

PURPOSE

Approximately 40-70% of biochemically persistent or recurrent prostate cancer (PCa) patients after radical prostatectomy (RPE) are oligo-metastatic in ⁶⁸gallium-prostate-specific membrane antigen positron emission tomography (⁶⁸Ga-PSMA PET). Those lesions are frequently located outside the prostate bed, and therefore not cured by the current standards of care like external-beam radiotherapy (EBRT) of the prostatic fossa. This retrospective study analyzes the influence of oligo-metastases' site on outcome after metastasis-directed radiotherapy (MDR).

METHODS

Retrospectively, 359 patients with PET-positive PCa recurrences after RPE were analyzed. Biochemical recurrence-free survival (BRFS) (prostate-specific antigen (PSA) < post-radiotherapy nadir + 0.2 ng/mL) was assessed using Kaplan-Meier survival and Cox regression analysis.

RESULTS

All patients were initially clinically without distant metastases (cM0). Seventy-five patients had local recurrence within the prostatic fossa, 32 patients had pelvic nodal plus local recurrence, 117 patients had pelvic nodal recurrence, 51 patients had paraaortic lymph node metastases with/without locoregional recurrence, and 84 patients had bone or visceral metastases with/without locoregional recurrence. Median PSA before MDR was 1.2 ng/mL (range, 0.04-47.5). Additive androgen deprivation therapy (ADT) was given in 35% (125/359) of patients. Median PSA nadir after MDR was 0.23 ng/mL (range, < 0.03-18.30). After a median follow-up of 16 months (1-57), 239/351 (68%) patients had no biochemical recurrence. Patients with distant lymph node and/or distant metastases, the so-called oligo-body cohort, had an overall in-field control of 90/98 (91%) but at the same time, an ex-field progress of 44/96 (46%). In comparison, an ex-field progress was detected in 28/154 (18%) patients with local and/or pelvic nodal recurrence (oligo-pelvis group). Compared with the oligo-pelvis group, there was a significantly lower BRFS in oligo-body patients at the last follow-up.

CONCLUSION

Overall, BRFS was dependent on patterns of metastatic disease. Thus, MDR of PSMA PET-positive oligo-metastases can be offered considering that about one-third of the patients progressed within a median follow-up of 16 months.

Quantification of Tumor Oxygenation Based on FMISO PET: Influence of Location and Oxygen Level of the Well-Oxygenated Reference Region

Tumor hypoxia may play a fundamental role in determining the radiotherapy outcome for several cancer types. Functional imaging with hypoxia specific radiotracers offers a way to visualize and quantify regions of increased radioresistance, which may benefit from dose escalation strategies. Conversion of the uptake in positron emission tomography (PET) images into oxygenation maps offers a way to quantitatively characterize the microenvironment. However, normalization of the uptake with respect to a well-oxygenated reference volume (WOV), which should be properly selected, is necessary when using conversion functions. This study aims at assessing the sensitivity of quantifying tumor oxygenation based on ¹⁸F-fluoromisonidazole (FMISO) PET with respect to the choice of the location and the oxygenation level of the WOV in head and neck cancer patients. WOVs varying not only in shape and location but also with respect to the assigned pO₂ level were considered. pO₂ values other than the standard 60 mmHg were selected according to the specific tissue type included in the volume. For comparison, the volume which would be considered as hypoxic based on a tissue-to-muscle ratio equal to 1.4 was also delineated, as conventionally done in clinical practice. Hypoxia mapping strategies are found highly sensitive to selection of the location of well-oxygenated region, but also on its assigned oxygenation level, which is crucial for hypoxia-guided adaptive dose escalation strategies.

Proteome Profiling of Primary Pancreatic Ductal Adenocarcinomas Undergoing Additive Chemoradiation Link ALDH1A1 to Early Local Recurrence and Chemoradiation Resistance

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis with frequent post-surgical local recurrence. The combination of adjuvant chemotherapy with radiotherapy is under consideration to achieve a prolonged progression-free survival (PFS). To date, few studies have determined the proteome profiles associated with response to adjuvant chemoradiation. We herein analyzed the proteomes of primary PDAC tumors subjected to additive chemoradiation after surgical resection and achieving short PFS (median 6 months) versus prolonged PFS (median 28 months). Proteomic analysis revealed the overexpression of Aldehyde Dehydrogenase 1 Family Member A1 (ALDH1A1) and Monoamine Oxidase A (MAOA) in the short PFS cohort, which were corroborated by immunohistochemistry. In vitro, specific inhibition of ALDH1A1 by A37 in combination with gemcitabine, radiation, and chemoradiation lowered cell viability and augmented cell death in MiaPaCa-2 and Panc 05.04 cells. ALDH1A1 silencing in both cell lines dampened cell proliferation, cell metabolism, and colony formation. In MiaPaCa-2 cells, ALDH1A1 silencing sensitized cells towards treatment with gemcitabine, radiation or chemoradiation. In Panc 05.04, increased cell death was observed upon gemcitabine treatment only. These findings are in line with previous studies that have suggested a role of ALDH1A1 chemoradiation resistance, e.g., in esophageal cancer. In summary, we present one of the first proteome studies to investigate the responsiveness of PDAC to chemoradiation and provide further evidence for a role of ALDH1A1 in therapy resistance.

Standard of Care Versus Metastases-directed Therapy for PET-detected Nodal Oligorecurrent Prostate Cancer Following Multimodality Treatment: A Multi-institutional Case-control Study

BACKGROUND

Most prostate cancer (PCa) patients with a biochemical failure following primary multimodality treatment (surgery and postoperative radiotherapy) relapse in the nodes.

OBJECTIVE

To perform a matched-case analysis in men with lymph node recurrent PCa comparing standard of care (SOC) with metastasis-directed therapy (MDT).

DESIGN, SETTING, AND PARTICIPANTS

PCa patients with a prostate-specific antigen (PSA) progression following multimodality treatment were included in this retrospective multi-institutional analysis.

INTERVENTION

The SOC cohort (n=1816) received immediate or delayed androgen deprivation therapy administered at PSA progression. The MDT cohort (n=263) received either salvage lymph node dissection (n=166) or stereotactic body radiotherapy (n=97) at PSA progression to a positron emission tomography-detected nodal recurrence.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint, cancer-specific survival (CSS), was analyzed using the Kaplan-Meier method, log-rank test, Cox proportional hazards models, and propensity score-matched analyses.

RESULTS AND LIMITATIONS

At a median follow-up of 70 (interquartile range: 48-98) mo, MDT was associated with an improved CSS on univariate (p=0.029) and multivariate analysis (hazard ratio: 0.33, 95% confidence interval [CI]: 0.17-0.64) adjusted for the year of radical prostatectomy (RP), age at RP, PSA at RP, time from RP to PSA progression, Gleason score, surgical margin status, pT- and pN-stage. In total, 659 men were matched (3:1 ratio). The 5-yr CSS was 98.6% (95% CI: 94.3-99.6) and 95.7% (95% CI: 93.2-97.3) for MDT and SOC, respectively (p=0.005, log-rank). The main limitations of our study are its retrospective design and lack of standardization of systemic treatment in the SOC cohort.

CONCLUSIONS

MDT for nodal oligorecurrent PCa improves CSS as compared with SOC. These retrospective data from a multi-institutional pooled analysis should be considered as hypothesis-generating and inform future randomized trials in this setting.

PATIENT SUMMARY

Prostate cancer patients experiencing a lymph node recurrence might benefit from local treatments directed at these lymph nodes.

Customized treatment of recurrent gynaecological cancer--the need for intraoperative radiation therapy

OBJECTIVE

The objective of this retrospective study was to analyze the experience with intraoperative radiation therapy (IORT) at the present institution and to evaluate its contribution to the management of patients with recurrent gynecological cancer. Materials and

METHODS

Retrospectively this study reviewed data of patients with a gynecological malignancy considered for treatment with IORT at Freiburg University Medical Center between 2005 and 2012. For this purpose, an analysis of medical records, radiation oncology records, operation reports, and follow-up data was conducted.

RESULTS

During the period of this study, 31 women with gynecological cancer underwent tumor resection in combination with IORT. The median age of the patients at the time of IORT was 62 years (range 38-85). Most patients had undergone surgery at the time of initial diagnosis (87%). More than one-third of the patients received prior radiation therapy. In addition to that, 52% of the patients had already received chemotherapy. The majority of patients suffered from the first relapse of their disease. The local recurrence was predominantly located at the pelvic side wall (32%) or in intra-abdominal lymph nodes (32%). In 12 patients the authors did not apply the planned IORT. Intraoperative complications were rare and IORT was tolerated without severe side-effects. Follow-up was 14 months (range 1-65), progression free survival (PFS) was five months (range 3-31).

CONCLUSIONS

In carefully selected patients, IORT and cytoreductive surgery contributed to local control and disease palliation. The authors therefore consider IORT an important aspect of modern cancer treatment.

[(18)F]FET-PET Imaging for Treatment and Response Monitoring of Radiation Therapy in Malignant Glioma Patients - A Review

In the treatment of patients suffering from malignant glioma, it is a paramount importance to deliver a high radiation dose to the tumor on the one hand and to spare organs at risk at one the other in order to achieve a sufficient tumor control and to avoid severe side effects. New radiation therapy techniques have emerged like intensity modulated radiotherapy and image guided radiotherapy that help facilitate this aim. In addition, there are advanced imaging techniques like Positron emission tomography (PET) and PET/CT which can help localize the tumor with higher sensitivity, and thus contribute to therapy planning, tumor control, and follow-up. During follow-up care, it is crucial to differentiate between recurrence and treatment-associated, unspecific lesions, like radiation necrosis. Here, too, PET/CT can facilitate in differentiating tumor relapse from unspecific changes. This review article will discuss therapy response criteria according to the current imaging methods like Magnet resonance imaging, CT, and PET/CT. It will focus on the significance of PET in the clinical management for treatment and follow-up.

Treatment of recurrent prostate cancer following radical prostatectomy: the radiation-oncologists point of view

Recurrence of prostate cancer after radical prostatectomy is a common event. Salvage radiation therapy (RT) is the mainstay of treatment in cases with recurrence defined as PSA failure, offering the chance of cure. Multiple studies showed that the lower the PSA level at the beginning of salvage RT, the better the treatment outcome. There is evidence that higher radiation doses are associated with improved PSA relapse free rates. Four different recurrence patterns exist: 1) local recurrence in the prostatectomy bed only; 2) loco-regional metastases in the pelvic lymph nodes; 3) distant metastases (most commonly nodal or osseous); 4) a combination of local and distant recurrence. Modern functional imaging modalities like magnetic resonance imaging (MRI) and choline-PET/CT offer additional information to clinical and therapeutic variables and provide high accuracy depending on the level of PSA recurrence and PSA kinetics. These image modalities are valuable tools that can be used for gross tumor volume (GTV) definition in the RT-planning process in the salvage RT setting and guide interdisciplinary salvage therapy strategies in case of locoregional relapse. We discuss the impact of MRI and choline-PET/CT in the salvage setting from the radiation-oncologist point of view.

Use of the Graded Prognostic Assessment (GPA) score in patients with brain metastases from primary tumours not represented in the diagnosis-specific GPA studies

BACKGROUND AND PURPOSE

Assessment of prognostic factors might influence treatment decisions in patients with brain metastases. Based on large studies, the diagnosis-specific graded prognostic assessment (GPA) score is a useful tool. However, patients with unknown or rare primary tumours are not represented in this model. A pragmatic approach might be use of the first GPA version which is not limited to specific primary tumours.

PATIENTS AND METHODS

This retrospective analysis examines for the first time whether the GPA is a valid score in patients not eligible for the diagnosis-specific GPA. It includes 71 patients with unknown primary tumour, bladder cancer, ovarian cancer, thyroid cancer or other uncommon primaries. Survival was evaluated in uni- and multivariate tests.

RESULTS

The GPA significantly predicted survival. Moreover, improved survival was seen in patients treated with surgical resection or radiosurgery (SRS) for brain metastases. The older recursive partitioning analysis (RPA) score was significant in univariate analysis. However, the multivariate model with RPA, GPA and surgery or SRS versus none showed that only GPA and type of treatment were independent predictors of survival.

CONCLUSION

Ideally, cooperative research efforts would lead to development of diagnosis-specific scores also for patients with rare or unknown primary tumours. In the meantime, a pragmatic approach of using the general GPA score appears reasonable.

PET and SPECT for radiation treatment planning

Positron emission tomography (PET) and single photon computed emission tomography (SPECT) have been evaluated in several studies for radiation treatment planning in patients with primary brain tumors. PET with the glucose analogue fluorodeoxyglucose has been found to be of limited use for radiation treatment planning because the high physiologic glucose use of normal gray matter makes delineation of tumors challenging. In contrast, there is considerable evidence that PET or SPECT with radiolabeled amino acid or amino acid analogues provides valuable information for the delineation of gliomas. Increased amino acid uptake has been found to be a more specific marker for viable tumor tissue than signal abnormalities on MRI. In addition, increased amino acid uptake is frequently observed in tumor areas that have not caused a disruption of the blood brain barrier. Therefore, PET and SPECT with radiolabeled amino acids provide a unique opportunity to visualize the infiltrative growth of gliomas and use this information for radiation treatment planning.

Does overall treatment time impact on survival after whole-brain radiotherapy for brain metastases?

PURPOSE To evaluate whether reduced overall treatment time (OTT), i.e., administration of more than 5 fractions per week, or uncompensated treatment interruption resulting in increased OTT influences survival of patients treated with whole-brain radiotherapy (WBRT) for brain metastases. METHODS Retrospective multi-institutional intention-to-treat study including 233 patients treated with primary WBRT (prescribed dose 10 fractions of 3 Gy; no previous SRS or surgery) administered over 10-38 days. Four groups were studied: OTT 10-11 vs. 12 days, 13-15 or >15 days. RESULTS Fourteen patients (6%) failed to complete WBRT and received 3-9 fractions (median 7). Their median survival was 0.5 months as compared to 3 months in patients who completed WBRT. No significant impact of OTT on survival was found. Median survival was 1.5, 2.9, 3.0 and 3.1 months in the four groups mentioned above. CONCLUSIONS Compensation for unintended treatment interruption is generally recommended but might not always be feasible. Depending on histological tumour type or expected repopulation, prognostic factors and neurological status, it might be acceptable to complete an interrupted course of WBRT without compensation in selected patients. While survival might be largely independent from OTT, it should also be evaluated whether this parameter has any impact on quality of life and duration of palliation.

[Therapy of posterior orbital tumors]

Tumors of the posterior orbit require different therapeutic modalities, depending on the histological entity. In the orbit all structures are in close relationship and the endocranium is in the direct proximity. This requires profound knowledge of topographic anatomy and high therapeutic precision. The surgical approach to the posterior orbit via a ventral intraorbital approach is strongly restricted due to the ocular bulb which consumes most space in the anterior orbit. Therefore if the bulb and vision are to be retained extraorbital surgical corridors are predominantly preferred. These are classified into extracranial and intracranial approaches. In detail, the former are medial transethmoidal orbitotomy, caudal transmaxillar orbitotomy and lateral orbitotomy. Frontolateral and frontotemporal orbitotomy as well as frontal, bifrontal and subfrontal orbitotomy are intracranial approaches. Apart from surgical methods there are several forms of radiotherapy which can be applied to orbital tumors under certain indications. Radiotherapy may be performed with external fractionated photon radiation or as stereotactic radiation, with heavy ions or protons or as brachytherapy. In this article various therapeutic interventions to the posterior orbit and the indications and potential side-effects are described.

Tumour hypoxia imaging with [18F]FAZA PET in head and neck cancer patients: a pilot study

PURPOSE

Hypoxia is an important negative prognostic factor for radiation treatment of head and neck cancer. This study was performed to evaluate the feasibility of use of (18)F-labelled fluoroazomycin arabinoside ([(18)F]FAZA) for clinical PET imaging of tumour hypoxia.

METHODS

Eleven patients (age 59.6 +/- 9 years) with untreated advanced head and neck cancer were included. After injection of approximately 300 MBq of [(18)F]FAZA, a dynamic sequence up to 60 min was acquired on an ECAT HR+ PET scanner. In addition, approximately 2 and 4 h p.i., static whole-body PET (n = 5) or PET/CT (n = 6) imaging was performed. PET data were reconstructed iteratively (OSEM) and fused with CT images (either an external CT or the CT of integrated PET/CT). Standardised uptake values (SUVs) and tumour-to-muscle (T/M) ratios were calculated in tumour and normal tissues. Also, the tumour volume displaying a T/M ratio >1.5 was determined.

RESULTS

Within the first 60 min of the dynamic sequence, the T/M ratio generally decreased, while generally increasing at later time points. At 2 h p.i., the tumour SUV(max) and SUV(mean) were found to be 2.3 +/- 0.5 (range 1.5-3.4) and 1.4 +/- 0.3 (range 1.0-2.1), respectively. The mean T/M ratio at 2 h p.i. was 2.0 +/- 0.3 (range 1.6-2.4). The tumour volume displaying a T/M ratio above 1.5 was highly variable. At 2 h p.i., [(18)F]FAZA organ distribution was determined as follows: kidney > gallbladder > liver > tumour > muscle > bone > brain > lung.

CONCLUSION

[(18)F]FAZA PET imaging appears feasible in head and neck cancer patients, and the achieved image quality is adequate for clinical purposes. Based on our initial results, [(18)F]FAZA warrants further evaluation as a hypoxia PET tracer for imaging of cancer.

11C-Methionine Positron Emission Tomography for Preoperative Evaluation of Suggestive Low-Grade Gliomas

OBJECTIVE

The treatment regimen for cerebral gliomas is different, depending on the histological grade of the lesion. The therapeutic strategy for anaplastic gliomas and glioblastomas is more aggressive, including microsurgical removal, radiation and chemotherapy. The management for low-grade gliomas is still under discussion, operation or "wait and see" tactics are possible options. Therefore the diagnostic imaging procedures are crucial for further treatment planning. Although most of the low-grade gliomas appear as hypointense lesions without contrast medium (CM) enhancement on magnetic resonance images, in some cases lesions without CM enhancement can be anaplastic tumours as well. 11C-Methionine positron emission tomography (MET-PET) was performed for preoperative evaluation of non or low CM enhancing intracerebral lesions, so-called suggestive low-grade gliomas.

METHOD

20 patients harbouring suggestive low-grade gliomas were included. Seventeen patients were found to be candidates for open surgery and 3 patients were planned for stereotactic biopsy due to the localisation of the lesions. MET-PET studies were performed a few days prior to surgery. On the day of surgery MRI sequences for neuronavigation planning were carried out (MPRAGE and FLAIR sequences). All image data were fused for operation with neuronavigation-guided microsurgery or stereotactic biopsy (BrainLAB Neuronavigation system, VectorVision 6.1). Biopsies were taken from the MET uptake areas as well as from areas without MET uptake.

RESULTS

2/20 patients showed sparse CM enhancement on MRI T (1) images, 18/20 patients had lesions without CM enhancement. MET uptake was found in 16/20 cases (T/N ratio 1.5 or more) and no MET uptake was documented in 4/20 cases (T/N ratio <1.5). Histologically the 2 patients with sparse CM enhancement and MET uptake were glioblastoma multiforme, 10/14 patients with MET uptake and without CM enhancement had an anaplastic astrocytoma WHO III, 3/14 with MET uptake and no CM enhancement had an anaplastic oligoastrocytoma WHO III, and 1/14 had an oligoastrocytoma grade II. The lesions of the 4 patients without MET uptake and without CM enhancement were classified as astrocytoma grade II in 2 cases, as astrocytoma grade I in 1 case and as astrocytoma III in one case.

CONCLUSION

According to the results of this study, we find MET-PET to be a helpful tool for pretreatment evaluation of non-CM enhancing, suggestive low-grade intracerebral lesions. MET-PET adds valuable information for the decision-making for surgery or stereotactic biopsy.

Report of a male patient with brain metastases from breast cancer

As in female patients, the clinical course in male patients with breast cancer is determined mainly by tumor stage. The literature contains very limited data on either the occurrence or the treatment of CNS metastases. This paper presents the case report of a 69-year-old man with multiple brain metastases 7 years after a diagnosis of lymph-node positive breast cancer, which had earlier already spread to the bones and liver. Whole-brain irradiation with a total dose of 30Gy resulted in palliation of symptoms. Nevertheless, survival was very short (7 weeks from diagnosis). Patients with metastatic breast cancer are at risk for the development of brain metastases. When performance status is poor the survival of patients with brain metastases is very limited. Treatment recommendations are the same as those for female patients with brain metastases from breast cancer.

[Stereotactic radiation therapy with a modified linear accelerator in patients with brain metastases]

The aim of the study was to analyze the results of stereotactic radiotherapy using a linear accelerator in patients with brain metastases. We quantified the following clinical parameters: tumor response and tumor control after therapy, survival, and side effects. Results of the treatment were compared with those from traditional treatment strategies such as surgery and whole brain irradiation. Sixty patients with brain metastases (80 lesions, 36 men and 24 women, mean age 57 years) were treated with stereotactic radiotherapy. The mean follow-up time was 13 months.

CONCLUSION

Stereotactic radiotherapy is an important option in the treatment strategy for patients with brain metastases. In comparison to whole brain irradiation, stereotactic radiotherapy achieved a higher local tumor control with a lower rate of side effects. In comparison to surgery, stereotactic radiotherapy has the advantages of shorter treatment time and lower treatment-related morbidity and mortality.

Perspectives in the treatment of malignant gliomas in adults

Over the last two decades, after establishing the role of postoperative radiotherapy for malignant gliomas, no definitive improvement in survival rate could be observed, despite advances in established treatment modalities such as radiotherapy and chemotherapy. Progress in exploration of the biology of these tumours allowed for translational research projects and the development of rational new approaches, such as gene therapy and immunotherapy, that could interfere with established treatment regimens or be used independently. Possible strategies include the restoration of defective cancer-inhibitory genes, cell transduction or transfection with antisense DNA corresponding to genes coding for growth factors and their receptors, or with the so-called 'suicide genes'. Several antiangiogenic approaches such as administration of thalidomide, protamine, or monoclonal antibodies against vascular endothelial growth factor have been developed, too. Further treatment possibilities include modulation of drug resistance, e.g. by P-glycoprotein antagonists or 06-alkyl-guanine-DNA-transferase inhibitors, inhibition of matrix metalloproteinases, inhibition of protein kinase C and administration of agents such as phenylbutyrate or valproic acid that showed promising antiproliferative effects in vitro. This review discusses the available laboratory and clinical data as well as recent advances in our knowledge about prognostic and predictive factors and their implications for the design of future clinical trials.

Correlation between postoperative 3-[(123)I]iodo-L-alpha-methyltyrosine uptake and survival in patients with gliomas

The aim of this study was to evaluate the prognostic value of SPECT imaging using the amino acid analog 3-[(123)I]iodo-L-alpha-methyltyrosine (IMT) in patients with gliomas.

METHODS

One hundred fourteen consecutive patients with newly diagnosed gliomas were examined by IMT SPECT (low-grade glioma, n = 12; anaplastic astrocytoma or oligodendroglioma, n = 46; glioblastoma, n = 56). Seventy-one of these patients had undergone tumor resection 4-6 wk before SPECT imaging (group A). Forty-three patients with unresectable tumors were examined after stereotactic biopsy (group B). IMT uptake at the site of the tumor was assessed visually and quantified relative to a contralateral reference region (IMT uptake ratio). After IMT SPECT, all patients were treated with conformal radiotherapy. The median follow-up time was 27 mo.

RESULTS

In group A, focal IMT uptake at the resection site was visible in 52 of 71 patients (73%). Median survival was only 13 mo in these patients, whereas median survival was reached in patients without focal IMT uptake (P = 0.02). Furthermore, the intensity of IMT uptake significantly correlated with survival: patients with an IMT uptake ratio > 1.7 were at a 4.6 times higher risk of death than were patients with a lower IMT uptake (P < 0.001). The IMT uptake ratio remained a significant prognostic factor when age and grading were included in a multivariate model. In contrast, IMT uptake did not correlate with survival in group B (P = 0.95).

CONCLUSION

In patients with unresectable high-grade gliomas, IMT uptake appears not to correlate with the biologic aggressiveness of tumor cells. Nevertheless, the clear association between focal IMT uptake after tumor resection and poor survival suggests that IMT is a specific marker for residual tumor tissue. Therefore, IMT SPECT is expected to become a valuable tool for the planning and monitoring of local therapeutic modalities.

A comparison of treatment results for recurrent malignant gliomas

Retreatment of malignant gliomas may be performed with palliative intent after careful consideration of the risks and benefits, and with special regards to iatrogenic neurotoxicity and quality of life (QOL). This review compares studies of several retreatment strategies (published between 1987 and 2000) based on the quality of their evidence. Depending on both established prognostic factors and previous treatment, individually tailored retreatment strategies are possible. In all studies that included a multivariate analysis of prognostic factors, performance status was the most important. So far, predictive factors for response, which might facilitate patient selection, have not been unequivocally defined. In terms of QOL, single-agent chemotherapy (temozolomide, nitrosoureas, platinum and taxane derivatives) may offer a better therapeutic ratio than polychemotherapy. For glioblastoma multiforme, progression-free survival and QOL were more favourable after temozolomide than procarbazine (level 1 evidence). The survival of patients after various radiotherapy techniques is broadly similar. However, considerable toxicity is associated with radiosurgery or brachytherapy. Fractionated stereotactic radiotherapy plus radio-sensitizing cytostatic agents has shown promising initial results in small groups of selected patients and awaits further evaluation. Level 2 evidence derived from non-randomized studies does not suggest a substantial prolongation of survival by re-resection as compared with chemotherapy or radiotherapy alone. Level 1 evidence derived from a randomized trial suggests that application of BCNU polymers significantly improves the outcome after re-resection. However, most studies reported median survival in the range of only 25-35 weeks, thereby emphasizing the need for the development and clinical evaluation of new innovative treatment approaches.

O-(2-[18F]fluoroethyl)-L-tyrosine and L-[methyl-11C]methionine uptake in brain tumours: initial results of a comparative study

O-(2-[18F]Fluoroethyl)-L-tyrosine (FET) is a recently described amino acid analogue that has shown high accumulation in animal tumours. The aim of this study was to compare the uptake of FET with that of L-[methyl-11C]methionine (MET) in patients with suspected primary or recurrent intracerebral tumours. Sixteen consecutive patients with intracerebral lesions were studied on the same day by positron emission tomography (PET) using MET and FET. Uptake of FET and MET was quantified by standardized uptake values. Tracer kinetics for normal brain and intracerebral lesions were compared. On the basis of the MET-PET studies, viable tumour tissue was found in 13 patients. All tumours showed rapid uptake of FET and were visualized with high contrast. Mean uptake of FET for normal grey matter, white matter and tumour tissue was 1.1+/-0.2, 0.8+/-0.2 and 2.7+/-0.8 SUV, respectively. In all three tissues, uptake of MET was slightly higher (1.4+/-0.2, 0.9+/-0.1 and 3.3+/-1.0 SUV; P<0.01). However, contrast between tumour and normal tissues was not significantly different between MET and FET. Uptake of FET in non-neoplastic lesions (1.0+/-0.1 SUV) was significantly lower than in tumour tissue (P = 0.007). For all lesions there was a close correlation (r = 0.98) between MET and FET uptake. In conclusion, in PET studies of human brain tumours, the uptake and image contrast of FET appear to be very similar to those of MET. The specificity of FET for tumour tissue is promising but has to be addressed in a larger series of patients with non-neoplastic lesions.

First experience with I-123-alpha-methyl-tyrosine spect in the 3-D radiation treatment planning of brain gliomas

PURPOSE

This study compares the results of iodine-123-alpha-methyl-tyrosine single photon computed emission tomography (IMT-SPECT) with magnetic resonance imaging (MRI) in tumor volume definition of brain gliomas. Furthermore, it evaluates the influences of the information provided from IMT-SPECT for three-dimensional (3D) conformal treatment planning.

METHODS AND MATERIALS

In 30 patients with nonresected, histologically proven brain gliomas (glioblastoma-13 patients, astrocytoma Grade III-12 patients, astrocytoma Grade II-3 patients, oligodendroglioma Grade III-1 patient, oligodendroglioma Grade II-1 patient), IMT-SPECT and MRI were performed pretherapeutically in the same week. A special software system allowed the coregistration of the IMT-SPECT and MRI data. The gross tumor volume (GTV) defined on the IMT-SPECT/T2-MRI fusion images (GTV-IMT/T2) was compared with the GTV-T2, defined on the T2-MRI alone. On the IMT-SPECT/T1Gd-MRI overlays, the volume of the IMT tumor uptake (GTV-IMT) was compared with the volume of the gadolinium (Gd) enhancement (GTV-T1Gd). The initial planning target volume (PTV) and the boost volume (BV) outlined on the IMT-SPECT/T2-MRI co-images were analyzed comparatively to the PTV and BV delineated using the T2-MRI alone.

RESULTS

In all 30 patients a higher IMT uptake of tumor areas, compared to the normal brain tissue was observed. Mean GTV-IMT, mean GTV-T2, and mean GTV-T1Gd were 43, 82, and 16 cm(3), respectively. IMT tumor uptake outside the contrast enhancement regions was observed in all patients. Mean relative increase of tumor volume defined on the fusion images, GTV-IMT/T1Gd versus GTV-T1Gd alone was 78%. IMT tumor uptake areas outside the GTV-T2 were registered in 7 patients (23%). In these patients, the mean increase GTV-IMT/T2 was 33% higher than GTV-T2, defined according to the T2-MRI data alone. The additional information provided by IMT-SPECT modified minimally the initial PTV (mean relative increase PTV-IMT/T2 versus PTV-T2, 5%) but significantly the BV (mean relative increase BV-IMT/T2 versus BV-T2, 37%).

CONCLUSION

In a significant number of patients, the IMT-SPECT investigation improves tumor detection and delineation in the planning process. This has important consequences in the 3D conformal treatment planning, especially in the delineation of BV and in dose escalation studies.

Treatment planning for conformal stereotactic radiotherapy

Due to three dimensional planning techniques it is possible to conform the high dose region precisely to a target volume inside the brain. Special patient fixation and positioning systems allow a high precision in repositioning of the patient thus allowing fractionated stereotactic radiotherapy. Conformation can be achieved with many different irradiation techniques for example with a linear accelerator using noncoplanar arcs or conformal static beams. Noncoplanar arc therapy with multiple isocenters and conformal static beam therapy with one isocenter are compared. In both cases the DVHs of the planning target volume and normal tissue are calculated and discussed.

[3-Dimensional irradiation planning in brain tumors. The advantages of the method and the clinical results]

PURPOSE

Radiotherapy became an important component in the treatment of brain gliomas. The aim of this study is to analyse several advantages of the three-dimensional conformal radiation therapy in comparison with a two-dimensional conventional technique and to present the clinical results of 43 patients with brain gliomas treated according to a three-dimensional planning.

PATIENTS AND METHOD

Between January 1994 and December 1995, 43 patients with malignant brain gliomas (WHO III and IV) were treated in our department according to a three-dimensional treatment planning. The patients received a total irradiation dose of 60 Gy, 2 Gy/day, 5 days/week. The rate of survival was analysed in relation with the known prognostical factors: histology, Karnofsky index, age, resection status. In 10 patients a three-dimensional treatment planning was compared with a conventional two-dimensional planning: the volume of the normal brain tissue irradiated to high dose levels (95% isodose) and the normal tissue complication probability (NTCP) for the brain by Kutcher and Lyman were comparatively analysed.

RESULTS

The survival rate for the whole group was 14 months. The histology of the tumor, age, Karnofsky index and resection status were important prognostical factors. The three-dimensional planning allows a 15 to 20% reduction in the volume of normal brain tissue irradiated to high dose levels (95% isodose). The NTCP is significantly lower using the three-dimensional technique (range 0.03% to 13%), in comparison with the two-dimensional conventional technique (range 0.1% to 26%). The value of NTCP increases with tumor volume.

CONCLUSIONS

Concerning the tumor control and survival rate, the three-dimensional treatment planning shows no advantages compared to the standard conventional methods. The main advantage of the three-dimensional treatment planning is the possibility to spare normal brain tissue. The possibility to integrate mathematical models in the evaluation of the therapy could give this technique new dimensions.