PAI-1 levels predict response to fractionated irradiation in 10 human squamous cell carcinoma lines of the head and neck.

BACKGROUND AND PURPOSE: To investigate the relationships between hypoxia, VEGF and components of the plasminogen activation system (PAS) and to determine their influence on local tumour control after fractionated radiotherapy. MATERIAL AND METHODS: Ten cell lines derived from human squamous cell carcinomas of the head and neck (SCCHN) were investigated in vitro and used to generate xenograft tumours. The pimonidazole hypoxic fraction in the total tumour area (pHF(tot)) was used to measure hypoxia in pre-treatment tumours and the local tumour control (TCD(50)) was used as the functional endpoint in vivo. For in vitro experiments, cells were cultured for 24h under either normoxic or mild hypoxic ( approximately 0.66% O(2)) conditions. VEGF, PAI-1 and uPA antigen levels were determined by ELISA and uPA activity by an activity assay kit. RESULTS: Of all the factors investigated, only PAI-1 expression correlated with TCD(50) (r=0.80, p=0.010) and was significantly higher (p=0.001) in more hypoxic than in less hypoxic tumours. Accordingly, PAI-1 secretion was significantly induced (2.4x) by in vitro hypoxia. CONCLUSIONS: These results suggest that pre-treatment PAI-1 levels are higher in more hypoxic tumours and can predict the response to fractionated irradiation in SCCHN.

Disease presentation and outcome in young patients (<40 years) with brain metastases from malignant melanoma.

While elderly patients with brain metastases from malignant melanoma apparently have an unfavourable prognosis, little information is available on disease presentation and treatment outcome in youngest patients. Considering this, our experience with radiation therapy in this particular subset was evaluated. Our database with 48 melanoma patients contained three patients aged <40 years. All received whole-brain radiation therapy plus steroids and individual systemic measures according to the institutional policy. In one case, brain metastases were present already at first diagnosis of melanoma. The maximum interval to diagnosis of brain metastases was 21 months. All the patients were male and had multiple lesions (at least 6) plus extracranial metastases. None of them died from extracranial disease. The maximum survival was 5 months. Thus, our young patients with brain metastases did not achieve a better outcome than intermediate age groups. Whole-brain radiation therapy was not able to provide durable CNS control. Prospective studies on treatment intensification appear warranted.

Disease presentation and outcome in very young patients with brain metastases from breast cancer.

AIMS AND BACKGROUND: Little information is available on disease presentation and treatment outcome in very young patients with brain metastases from breast cancer. Therefore, we evaluated our results in this group. METHODS: In our database, 7/74 breast cancer patients treated for brain metastases were < 40 years old. All received whole-brain radiation therapy plus individual local or systemic measures. RESULTS: In patients with information available, tumors were poorly differentiated and metastatic to the axillary lymph nodes at primary diagnosis. All patients had extracranial metastases. Two died from their brain disease within 5 months. Five patients died from extracranial progression after 3-84 months (2 long-term survivors beyond 2 years, characterized by single brain lesions and high performance status). CONCLUSIONS: Very young patients did not achieve a better outcome than intermediate age groups. Whole-brain radiation therapy plus surgery or radiosurgery provided durable CNS control in most of the patients. Improved systemic therapy appears to represent the key to a better outcome.

Therapeutic options for recurrent high-grade glioma in adult patients: recent advances.

Despite of postoperative radiotherapy plus temozolomide for newly diagnosed glioblastoma multiforme (GBM) and improvements in the molecular characterization of high-grade glioma, these tumors continue to relapse. We reviewed all clinical studies of re-treatment published between May 2000 and September 2005. In groups of highly selected patients with re-treatment for GBM, median survival reaches 26-27 months. Re-treatment was stereotactic radiotherapy (mostly with additional chemotherapy) or re-resection plus either photodynamic treatment, radioimmunotherapy and temozolomide, or systemic and local chemotherapy. Thus, intense local treatment was always a component of more successful strategies. Additional data suggest that chemotherapy is more efficacious when minimal residual disease is present, although the recent trials have not uncovered a clear regimen of choice. Early trials of immunotherapy and toxin-delivery demonstrate the feasibility of these approaches and encouraging median survival times. Response to erlotinib was more common if tumors had epidermal growth factor receptor gene amplification, protein overexpression and low levels of phosphorylated PKB/Akt. Individual tailoring of such strategies based on molecular profiling is hoped to improve the outcome.

11C-methionine PET improves the target volume delineation of meningiomas treated with stereotactic fractionated radiotherapy.

PURPOSE: To evaluate the role of 11C-methionine positron emission tomography (MET-PET) in target volume delineation for meningiomas and to determine the interobserver variability. METHODS AND MATERIALS: Two independent observers performed treatment planning in 10 patients according to a prospective written protocol. In the first step, they used coregistered computed tomography (CT) and magnetic resonance imaging (MRI). In the second step, MET-PET was added to CT/MRI (image fusion based on mutual information). RESULTS: The correlation between gross tumor volume (GTVs) delineated by the two observers based on CT/MRI was r=0.855 (Spearman's correlation coefficient, p=0.002) and r=0.988 (p=0.000) when MET-PET/CT/MRI were used. The number of patients with agreement in more then 80% of the outlined volume increased with the availability of MET-PET from 1 in 10 to 5 in 10. The median volume of intersection between the regions delineated by two observers increased significantly from 69% (from the composite volume) to 79%, by the addition of MET-PET (p=0.005). The information of MET-PET was useful to delineate GTV in the area of cavernous sinus, orbit, and base of the skull. CONCLUSIONS: The hypothesis-generating findings of potential normal tissue sparing and reduced interobserver variability provide arguments for invasive studies of the correlation between MET-PET images and histologic tumor extension and for prospective trials of target volume delineation with CT/MRI/MET-PET image fusion.

Multiparametric sensor-chip based technology for monitoring metabolic activity: A proof-of-principle study with live tissue.

The recent development of an electronic test system based on silicon sensor-chips allows the continuous parallel recording of relative changes in extracellular acidification, oxygen consumption and electric impedance in living cells. The objective of this proof-of-principle study therefore, was to clarify whether this system can also be applied to live tissue slices thus providing a device for an ultimately envisioned chemosensitivity testing apparatus for individualized treatment schemes in cancer therapy. A prototype of the testing apparatus equipped with six individual measuring devices has been used to simultaneously analyze changes in extracellular acidification, oxygen consumption and electronic impedance in live liver tissue and compared to data obtained from a tumor cell line. In contrast to tumor cells, tissue slices showed low rates of extracellular acidification but high rates of oxygen consumption. Monitoring of electrical impedance values, reflecting cellular morphology, revealed that the compact cell structure of the tissue slices was able to function as electric insulator and actively change the impedance values of the system. Exposure of tumor cells to 1 microM cytochalasin B, a fungal metabolite known to interact with the cytoskeleton and influence glucose metabolism, resulted in the rapid decline of extracellular acidification, increased oxygen consumption rates and increased values in capacitance. In tissue slices upon addition of 1 microM cytochalasin B, a decline of both extracellular acidification and electrical impedance was observed within 1 h. Determination of ATP content in the tissue slices revealed that decreasing ATP content paralleled diminishing oxygen consumption. This new technique offers the possibility of generating metabolic profiles for cells and tissues by studying oxygen consumption, extracellular acidification and electrical impedance.

The role of pentoxifylline as a modifier of radiation therapy.

Pentoxifylline (Ptx), a hemorrheologic methylxanthine derivative, is of interest in radiation oncology for several reasons. First, improvement of tumor perfusion might result in better oxygenation and thus radiosensitivity. In addition, the drug also influences cytokine-mediated inflammation. The role of cytokines in the progression of radiation reactions in both tumor and normal tissues therefore provides further opportunities to combine Ptx with ionising radiation in order to improve the therapeutic ratio. This review summarizes preclinical and clinical data in both tumor and normal tissues. Regarding radiosensitization of tumors, a large body of evidence suggests that Ptx improves tumor oxygenation and sensitizes p53 mutant tumors. However, these findings have not translated into positive clinical studies to date. None of three published clinical trials attempting to enhance the effectiveness of radiotherapy with Ptx had a satisfactory design. There is also little evidence to prove that Ptx reduces acute side effects of radiotherapy. The only possible exception is a small randomized trial of lung radiotherapy. Regarding established late sequelae, numerous non-randomized clinical trials described healing of soft tissue necrosis and improvement of trismus and fibrosis after several weeks of Ptx or Ptx plus vitamin E. However, is not unequivocally clear that the combination with vitamin E indeed is superior. The literature data suggest that radiation necrosis can be treated more effectively than fibrosis and that certain improvements might be functional and transient, with less influence on the chronic structural damage induced by ionising radiation. The ultimate individual outcome might depend, for example, on the stage of fibrosis progression, the size of the lesion and comorbid conditions such as diabetes and arteriosclerosis. Some of these factors will influence the actual amount of drug available in the targeted region. It is therefore necessary to evaluate Ptx in larger clinical trials with less baseline variation and to improve the recording of long-term results.

Prognostic value of tumor oxygenation in 397 head and neck tumors after primary radiation therapy. An international multi-center study.

PURPOSE: To analyze the relationship between pre-treatment measurements of tumor oxygen tension (pO2) and survival in advanced head and neck cancer. PATIENTS AND METHODS: Eppendorf pO2 measurements in 397 patients from seven centers were analyzed using the fraction of pO2 values < or =2.5 mmHg (HP2.5), < or =5 mmHg (HP5) and median tumor pO2 (mmHg) as descriptors. All patients had intended curative radiation therapy alone or as pre- or post-operative radiotherapy or radio-chemotherapy according to the practice at each center. RESULTS: The degree of hypoxia varied between tumors with an overall median tumor pO2=9 mmHg (range 0-62 mmHg), a median HP2.5=19% (range 0-97%) and HP5=38%, (range 0-100%). By quadratic regression median tumor pO2 correlated with Hb (2P=0.026, n=357), while HP2.5 or HP5 did not. HP2.5 above the population median was the only parameter that associated with poor overall survival (Kaplan Meier analysis, P=0.006). In a multivariate Cox Proportional Hazards analysis, stratified according to institution HP2.5 was by far the most statistically significant factor in explaining the variability in survival. After adjusting for HP2.5, clinical stage, radiation dose and surgery hemoglobin concentration was not significant in the model. The prognostic model shows that the 5-year survival is almost constant for HP2.5 values in the range from 0 to 20%, whereas the 5-year survival approaches 0% in the most hypoxic tumors. CONCLUSION: This study provides evidence that tumor hypoxia is associated with a poor prognosis in patients with advanced head and neck cancer.

Simultaneous precise chemoradiation under inhalation anesthesia in an experimental mouse tumor model.

BACKGROUND: Performing radiobiological experiments under general anesthesia is, in many cases, superior to treatment in unanesthetized animals or with intraperitoneal (i.p.) anesthesia. This is especially true for experiments where highly fractionated treatment schedules are used. MATERIALS AND METHODS: An anesthesia system was employed to overcome several of the limitations associated with the use of pentobarbital and other i.p.-administered anesthetics in experimental radiotherapy. RESULTS: Several different experiments with a total of 152 mice were performed. The total of all anesthesia exposures amounted to approximately 1,520. The duration of anesthesia ranged from 3 to 5 min per session. No complications related to the anesthetic procedure were observed. CONCLUSION: The present anesthesia/irradiation setup is a simple, safe and perfectly reproducible system where even multiple fractionated treatments can be performed under anesthesia with excellent tolerance. Our system allows easy and fast handling and immobilization and thus reduces experimental times.

Quality of training in radiation oncology in Germany. Results of a 2006 survey.

PURPOSE: To evaluate residents' satisfaction with their training in radiation oncology, the first nationwide survey was done in 2006. Results were presented at the 2006 annual meeting of the German Society of Radiation Oncology (DEGRO). MATERIAL AND METHODS: A questionnaire with 39 questions regarding training in radiation oncology in Germany was developed and sent by e-mail. Questionnaires were returned by mail and analyzed anonymously. RESULTS: 96 questionnaires were received. A total of 88% of respondents are pleased with their decision of training in radiation oncology. Residents are strongly motivated by their interest in oncology. Quality of training is heterogeneous and not optimal. Training in three-dimensional treatment planning, radiochemotherapy and intracavitary brachytherapy is judged adequate, whereas special techniques such as intensity-modulated radiotherapy (IMRT) and permanent prostate implants are not covered by the majority of institutions. Organization of training in the departments is often judged insufficient. CONCLUSION: Radiation oncology is attractive for young doctors. However, training quality for radiation oncologists in Germany was judged to be heterogeneous and needs to be optimized. For this, results of this survey may be helpful. The overall positive judgment may help to attract more students into the field of radiation oncology, an issue that becomes increasingly important given the shortage of doctors and the strong competition with other disciplines. Modern techniques, such as IMRT, need to be integrated into training programs in order to maintain the high standard of radiation oncology in Germany.

Tirapazamine plus cisplatin and irradiation in a mouse model: improved tumor control at the cost of increased toxicity.

PURPOSE: Tirapazamine (TPZ) reportedly enhances the tumor cell killing effect of cisplatin up to fivefold and it is an attractive drug for combination with radiotherapy. We evaluated the toxicity of a fractionated combined treatment. METHODS: Murine RIF-1 fibrosarcomas growing on the right hind foot of C3-H mice were used. Within 2 weeks, animals were treated with six i.p. injections of TPZ (43.2-172.8 mg/kg total), and/or cisplatin (24 mg/kg total) and ten fractions of 2 Gy to the tumor. All treatments were carried out under anesthesia. Maximum follow-up was 35 days. The local tumor control was determined by calculating the tumor doubling time t (2vo). In addition to standard toxicity assessment, the major inner organs were examined histologically. RESULTS: The administration of low TPZ doses to the cisplatin/radiotherapy treatment caused only little changes in tumor doubling time (t (2vo)) and led to a lethality rate of 15-30%. Higher TPZ doses caused an increase in t (2vo), but also a further increase in lethality and toxicity in particular to the heart, liver, kidney and stomach. Cisplatin/radiotherapy treatment without TPZ produced no severe toxicity. CONCLUSIONS: This is a detailed study of both the acute and delayed toxicities of combined TPZ treatment in a mouse model. In our study the addition of TPZ to the cisplatin/radiotherapy treatment caused a significant increase in toxicity with only moderate effect on the tumor.

Combined modality treatment of glioblastoma multiforme: the role of temozolomide.

Despite of improvements in the biological and molecular characterization of glioblastoma multiforme and studies of factors associated with tumor growth and progression, this type of malignant astroglial brain tumor is still difficult to treat. The present article reviews established and emerging prognostic and predictive factors and their potential influence on future therapeutic efforts. Recent developments in standard treatment options (surgery, radiotherapy and chemotherapy) are summarized. The integration of the oral cytotoxic agent temozolomide into current treatment protocols of postoperative combination therapy with radiation and drugs is discussed, especially in the context of the recently published randomized trial of the EORTC/NCIC, which showed that radiotherapy plus concomitant and adjuvant temozolomide significantly improved progression-free and overall survival over radiotherapy alone. The study also provided hypotheses about the subgroups, which are most likely to benefit from this reasonably well tolerated regimen. In a subset of patients, investigation of MGMT promoter methylation in tumor tissue was performed. Survival was shorter in patients with unmethylated promoter in both study groups. Patients with methylated promoter treated with radiotherapy had a median survival of 15 months, those treated with radiation plus temozolomide of 22 months (p=0.007). In the unmethylated group, the difference in median survival was only 1 month (p=0.06). Especially for these patients, alternative treatments need to be developed. The optimum schedule of temozolomide administration and the influence of combinations with additional antineoplastic agents remains to be studied. Early results of clinical trials addressing these issues are presented.

[Evaluation of the toxicity of tirapazamine plus cisplatin in a mouse tumor model]. / Untersuchungen zur Toxizität von Tirapazamine plus Cisplatin in einem Maus-Tumormodell.

BACKGROUND AND PURPOSE: Tirapazamine (TPZ) is an anticancer drug that is selectively activated by the low oxygen environment in solid tumors. Furthermore, TPZ also enhances the tumor cell-killing effect of cisplatin. So far, detailed information on the toxicity of combined treatment is rare. The authors evaluated the toxicity of TPZ in combination with cisplatin in a mouse tumor model. For this purpose, general toxicity was monitored and all inner organs were examined histologically. MATERIAL AND METHODS: RIF-1 fibrosarcomas of murine origin growing in the right hindfoot dorsum of C3H mice were used. The animals were treated with 10 x 2 Gy irradiation plus six i.p. injections of 4 mg/kg cisplatin (total dose 24 mg/kg) together with varying doses of TPZ (0-28 mg/kg per injection; total dose 0, 43.2, 86.4, 129.6, 151.2, 172.8 mg/kg). Treatment was applied within 2 weeks (Figure 1). Total observation period was up to 35 days. RESULTS: Combined treatment with TPZ led to a dose-dependent, significant decrease in motor activity (Table 1) and body weight and an increase in mortality (Figures 2 and 3, Tables 2 and 3). Histological analyses showed areas of necrosis in the heart, liver and kidney and gastric ulcers (Table 4). Cisplatin alone produced no severe toxicity. Tumor doubling times were TPZ dose-dependent and comparable with data from the literature (Figures 4 and 5, Table 3). CONCLUSION: Unlike most data from the literature a dose-dependent increase in toxicity was seen when adding TPZ to a standard treatment of cisplatin plus irradiation. To the authors' knowledge this is the first study histologically examining in detail the organ toxicity of TPZ in a mouse model. Furthermore, they expand the rare data on long-term toxicity after TPZ plus cisplatin in a fractionated therapy regimen. The results question the usefulness of frequently performed therapeutic studies where only short-term treatment and observation endpoints are used, since essential toxicities are likely to be overlooked.

Impact of hypoxia and the metabolic microenvironment on radiotherapy of solid tumors. Introduction of a multi-institutional research project.

BACKGROUND: Recent developments in imaging technology and tumor biology have led to new techniques to detect hypoxia and related alterations of the metabolic microenvironment in tumors. However, whether these new methods can predict radiobiological hypoxia and outcome after fractionated radiotherapy still awaits experimental evaluation. MATERIAL AND METHODS: The present article will introduce a multi-institutional research project addressing the impact of hypoxia and the metabolic microenvironment on radiotherapy of solid tumors. The four laboratories involved are situated at the universities of Dresden, Mainz, Munich and Würzburg, Germany. RESULTS: The joint scientific project started to collect data obtained on a set of ten different human tumor xenografts growing in nude mice by applying various imaging techniques to detect tumor hypoxia and related parameters of the metabolic microenvironment. These techniques include magnetic resonance imaging and spectroscopy, metabolic mapping with quantitative bioluminescence and single-photon imaging, histological multiparameter analysis of biochemical hypoxia, perfusion and vasculature, and immunohistochemistry of factors related to angiogenesis, invasion and metastasis. To evaluate the different methods, baseline functional radiobiological data including radiobiological hypoxic fraction and outcome after fractionated irradiation will be determined. CONCLUSION: Besides increasing our understanding of tumor biology, the project will focus on new, clinically applicable strategies for microenvironment profiling and will help to identify those patients that might benefit from targeted interventions to improve tumor oxygenation.