Stereotactic radiotherapy in the management of oligometastatic and recurrent head and neck cancer: a single-center experience

INTRODUCTION

Oligometastatic disease (OMD) is a metastatic stage that could benefit maximally from local therapies. Patients in this state have a better prognosis relative to those with disseminated metastases. Stereotactic radiotherapy provides a non-invasive ablative tool for primary malignant tumors and metastases.

MATERIALS AND METHODS

We searched our register for patients with oligometastatic or recurrent head and neck cancer (OMD/R-HNC) who received stereotactic radiotherapy to manage their OMD/R. We evaluated the survival outcomes and prognostic factors that affected the survival of those patients.

RESULTS

In all, 31 patients with 48 lesions met the inclusion criteria for the analysis. The lesions comprised various metastatic sites, with the majority being pulmonary (37 lesions). Squamous cell cancer was the most common histology (26 patients). The median overall survival (mOS) was 33 months, with a progression-free survival (PFS) of 9.6 months. Eight patients received subsequent stereotactic radiotherapy after disease progression. The local control (LC) rates were 91.3, 87.7, and 83% at 6, 12, and 36 months. Patients with the de novo OMD who received stereotactic radiotherapy as their initial treatment had a median systemic treatment-free survival of 23.9 months. In univariate analysis, a trend for better OS was observed in patients with p16-positive squamous cell tumors; patients who progressed within 150 days after diagnosis had a significantly lower OS. De novo OMD showed significantly better PFS compared to induced OMD. Multivariate analyses identified p16-positive squamous cell cancer, metachronous OMD and a longer time to progression as positive predictors of OS, while de novo OMD was the only positive predictor for PFS. Treatment-related toxicities were generally mild, with two cases of grade 3 dysphagia reported.

CONCLUSION

Stereotactic radiotherapy demonstrated favorable outcomes in patients with OMD/R-HNC with limited toxicities. Further studies are warranted to validate these findings and optimize treatment strategies for this patient population.

Managing hepatocellular carcinoma across the stages: efficacy and outcomes of stereotactic body radiotherapy : A retrospective study

PURPOSE

Hepatocellular carcinoma (HCC) poses a unique challenge due to its predilection for developing on compromised livers, often limiting surgical options. Stereotactic body radiotherapy (SBRT) has emerged as a promising local treatment modality for HCC. This study aims to assess the effectiveness of SBRT in HCC patients not suitable for surgery, focusing on local control, optimal radiation dosing, and prognostic factors.

METHODS

In this retrospective analysis, 52 HCC patients treated with SBRT were examined. The study assessed local control, progression-free survival (PFS), and overall survival (OS) while conducting dosimetric analyses. The relationship between mean liver dose and Child-Pugh score (CPS) progression was also explored.

RESULTS

SBRT demonstrated 93.4% freedom from local progression (FFLP) at 12 months. Notably, a near minimum dose (D98%) below 61 Gy as an equivalent dose in 2‑Gy fractions with α/β 10 Gy (EQD2α/β10) was associated with reduced FFLP (p-value 0.034). Logistic regression analysis revealed a dose-response relationship for FFLP and D98% with 95% and 98% probability of FFLP at a dose of 56.9 and 73.1 Gy, respectively. The study observed OS rates of 63.7% at 1 year and 34.3% at 3 years. Patients with portal vein tumor thrombus (PVTT) and larger tumors (≥ 37 cm3) experienced decreased PFS and OS. Multivariate analysis identified PVTT, larger tumor volume, and performance status as independent predictors of reduced OS. Notably, classical radiation-induced disease (cRILD) was absent, but nonclassical (nc) RILD occurred in 7.7% of patients. Regression analysis linked a mean EQD2α/β3-8 dose to the liver (12.8-12.6) with a 10% likelihood of ncRILD.

CONCLUSION

SBRT offers a compelling option for achieving high local control and promising survival outcomes in HCC. The study supports a radiation dose range of 61-73.1 Gy, coupled with a mean liver dose under 12.6-12.8 Gy as EQD2, to achieve favorable FFLP rates, with acceptable toxicity rates.

Radiotherapy Combined with PD-1 Inhibition Increases NK Cell Cytotoxicity towards Nasopharyngeal Carcinoma Cells

BACKGROUND

Nasopharyngeal carcinoma (NPC) in endemic regions and younger patients is characterized by a prominent lymphomononuclear infiltration. Radiation is the principal therapeutic modality for patients with NPC. Recent data suggest that the efficacy of radiotherapy in various cancers can be augmented when combined with immune checkpoint blockade. Here, we investigate the effect of radiotherapy on the killing of NPC cells by Natural Killer (NK) cells.

METHODS

NPC cell lines and a patient-derived xenograft were exposed to NK cells in the context of radiotherapy. Cytotoxicity was measured using the calcein-release assay. The contribution of the PD-L1/PD-1 checkpoint and signaling pathways to killing were analyzed using specific inhibitors.

RESULTS

Radiotherapy sensitized NPC cells to NK cell killing and upregulated expression of PD-1 ligand (PD-L1) in NPC cells and PD-1 receptor (PD-1) in NK cells. Blocking of the PD-L1/PD-1 checkpoint further increased the killing of NPC cells by NK cells in the context of radiotherapy.

CONCLUSION

Radiation boosts the killing of NPC cells by NK cells. Killing can be further augmented by blockade of the PD-L1/PD-1 checkpoint. The combination of radiotherapy with PD-L1/PD-1 checkpoint blockade could therefore increase the efficacy of radiotherapy in NPC tumors.

Molecular effects of photon irradiation and subsequent aftercare treatment with dexpanthenol-containing ointment or liquid in 3D models of human skin and non-keratinized oral mucosa

This study aimed to investigate the molecular effects of radiation and subsequent aftercare treatment with dexpanthenol-containing ointment and liquid on established full-thickness 3D skin models depicting acute radiodermatitis and mucositis. To mimic radiomucositis and radiodermatitis, non-keratinized mucous membrane and normal human skin models were irradiated with 5 Gray. Afterwards, models were treated topically every second day with dexpanthenol-containing ointment or liquid in comparison with placebo and untreated controls. On day 7 after irradiation, histological examination showed impairments in irradiated models. In contrast, models treated with dexpanthenol-containing ointment or liquid showed a completely restored epidermal part. While gene expression profiling revealed an induction of genes related to a pro-inflammatory milieu, oxidative stress and an impaired epidermal differentiation after irradiation of the models, aftercare treatment with dexpanthenol-containing ointment or liquid revealed anti-oxidative and anti-inflammatory effects and had a positive effect on epidermal differentiation and structures important for physical and antimicrobial barrier function. Our findings confirm the potential of our established models as in vitro tools for the replacement of pharmacological in vivo studies regarding radiation-induced skin injuries and give indications of the positive effects of dexpanthenol-containing externals after radiation treatments as part of supportive tumor treatment.

Correlating Dose Variables with Local Tumor Control in Stereotactic Body Radiation Therapy for Early-Stage Non-Small Cell Lung Cancer: A Modeling Study on 1500 Individual Treatments

BACKGROUND

Large variation regarding prescription and dose inhomogeneity exists in stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer. The aim of this modeling study was to identify which dose metric correlates best with local tumor control probability to make recommendations regarding SBRT prescription.

METHODS AND MATERIALS

We combined 2 retrospective databases of patients with non-small cell lung cancer, yielding 1500 SBRT treatments for analysis. Three dose parameters were converted to biologically effective doses (BEDs): (1) the (near-minimum) dose prescribed to the planning target volume (PTV) periphery (yielding BEDmin); (2) the (near-maximum) dose absorbed by 1% of the PTV (yielding BEDmax); and (3) the average between near-minimum and near-maximum doses (yielding BEDave). These BED parameters were then correlated to the risk of local recurrence through Cox regression. Furthermore, BED-based prediction of local recurrence was attempted by logistic regression and fast and frugal trees. Models were compared using the Akaike information criterion.

RESULTS

There were 1500 treatments in 1434 patients; 117 tumors recurred locally. Actuarial local control rates at 12 and 36 months were 96.8% (95% confidence interval, 95.8%-97.8%) and 89.0% (87.0%-91.1%), respectively. In univariable Cox regression, BEDave was the best predictor of risk of local recurrence, and a model based on BEDmin had substantially less evidential support. In univariable logistic regression, the model based on BEDave also performed best. Multivariable classification using fast and frugal trees revealed BEDmax to be the most important predictor, followed by BEDave.

CONCLUSIONS

BEDave was generally better correlated with tumor control probability than either BEDmax or BEDmin. Because the average between near-minimum and near-maximum doses was highly correlated to the mean gross tumor volume dose, the latter may be used as a prescription target. More emphasis could be placed on achieving sufficiently high mean doses within the gross tumor volume rather than the PTV covering dose, a concept needing further validation.

[Terrorist attack training exercise-What can be learned? : Baden-Württemberg counterterrorism exercise (BWTEX)]

BACKGROUND

There is a risk of terror attacks in the Federal Republic of Germany, which might increase in the future. A timely comprehensive strategy for treatment and care of a large number of casualties helps minimize chaos and improve the outcome of patients. Adequate training is vital for successful implementation of an emergency plan. Therefore, the effectiveness of training should be assessed and evaluated; however, data collection capabilities for training events are extremely limited, so that publications on the topic are almost impossible to find.

OBJECTIVE

This study aimed to collect data from a simulated terrorist attack in order to draw conclusions from a clinical point of view concerning the improvement of preclinical and clinical management, taking interface problems into consideration.

MATERIAL AND METHODS

On 19 October 2019 the Ministry of the Interior, Digitalization and Migration of Baden-Württemberg conducted a large-scale simulation of a terrorist attack in the city center of Constance, called the Baden-Württemberg counterterrorism exercise (BWTEX). The simulation included an explosion of a car bomb as well as the use of firearms by terrorists. The large scale of the simulation with the high number of participants in combination with close cooperation between military and civil forces was unprecedented. The police force, the armed forces, civil protection forces, air rescue teams and staff from Constance, Friedrichshafen and Sigmaringen regional hospitals in southwest Germany worked together to treat simulated injuries to victims of the attack. The following parameters were recorded when the injured patients arrived at the hospital: prehospital triage time, prehospital triage score, initial treatment and quality of documentation on site as well as triage time, triage score, injury severity scale (ISS) score based on the specified injury pattern, treatment, and quality of documentation on hospital arrival.

RESULTS

Out of a total of 84 "injured patients" 55 were admitted to hospital and 80% were triaged at the scene. Injured patients of triage category 1 (TK1 red: life-threatening injury, immediate treatment) arrived at the hospital 198 ± 50 min after the attack, injured patients of triage category 2 (TK2 yellow: severely injured, urgent treatment) after 131 ± 44 min and injured patients of triage category 3 (TK3 green: slightly injured, non-urgent treatment) arrived after 157 ± 46 min. There was no significant difference in terms of arrival time at the hospital between the triage scores (r = 0.2) or between the ISS scores (r = 0.43). The authors assume that approximately 44% of TK1 patients would have died due to avoidable time delays. Prehospital medical documentation was insufficient in 78% and insufficient in 65% in the hospitals.

CONCLUSION

A mass casualty incident resulting from a terrorist attack differs greatly from a conventional mass casualty incident. The scene of the attack has to be evacuated as quickly as possible, which means that a large number of patients arrive untreated at the nearest hospitals. The setting up of treatment facilities in city centers and areas close to the city seems to be counterproductive because the time delay may result in higher mortality rates of victims. The particularities of mass casualties caused by a terrorist attack have to be incorporated into terrorist attack training.

Infrastructure and distributed learning methodology for privacy-preserving multi-centric rapid learning health care: euroCAT

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Developed and implemented IT infrastructure in 5 radiation clinics across 3 countries.

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Proof-of-principle for ‘big data’ infrastructure and distributed learning studies.

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General framework to execute learning algorithms on distributed data.

Machine learning applications for personalized medicine are highly dependent on access to sufficient data. For personalized radiation oncology, datasets representing the variation in the entire cancer patient population need to be acquired and used to learn prediction models. Ethical and legal boundaries to ensure data privacy hamper collaboration between research institutes. We hypothesize that data sharing is possible without identifiable patient data leaving the radiation clinics and that building machine learning applications on distributed datasets is feasible.

We developed and implemented an IT infrastructure in five radiation clinics across three countries (Belgium, Germany, and The Netherlands). We present here a proof-of-principle for future ‘big data’ infrastructures and distributed learning studies. Lung cancer patient data was collected in all five locations and stored in local databases. Exemplary support vector machine (SVM) models were learned using the Alternating Direction Method of Multipliers (ADMM) from the distributed databases to predict post-radiotherapy dyspnea grade ⩾2. The discriminative performance was assessed by the area under the curve (AUC) in a five-fold cross-validation (learning on four sites and validating on the fifth). The performance of the distributed learning algorithm was compared to centralized learning where datasets of all institutes are jointly analyzed.

The euroCAT infrastructure has been successfully implemented in five radiation clinics across three countries. SVM models can be learned on data distributed over all five clinics. Furthermore, the infrastructure provides a general framework to execute learning algorithms on distributed data. The ongoing expansion of the euroCAT network will facilitate machine learning in radiation oncology. The resulting access to larger datasets with sufficient variation will pave the way for generalizable prediction models and personalized medicine.

Chloroquine Sensitizes Nasopharyngeal Carcinoma Cells but Not Nasoepithelial Cells to Irradiation by Blocking Autophagy

BACKGROUND

Treatment of nasopharyngeal carcinoma requires the application of high dosages of radiation, leading to severe long-term complications in the majority of patients. Sensitizing tumor cells to radiation could be a means to increase the therapeutic window of radiation. Nasopharyngeal carcinoma cells display alterations in autophagy and blockade of autophagy has been shown to sensitize them against chemotherapy.

METHODS

We investigated the effect of chloroquine, a known inhibitor of autophagy, on sensitization against radiation-induced apoptosis in a panel of five nasopharyngeal carcinoma cell lines and a SV40-transformed nasoepithelial cell line. Autophagy was measured by immunoblot of autophagy-related proteins, immunofluorescence of autophagosomic microvesicles and electron microscopy. Autophagy was blocked by siRNA against autophagy-related proteins 3, 5, 6 and 7 (ATG3, ATG5, ATG6 and ATG7).

RESULTS

Chloroquine sensitized four out of five nasopharyngeal cancer cell lines towards radiation-induced apoptosis. The sensitizing effect was based on the blockade of autophagy as inhibition of ATG3, ATG5, ATG6 and ATG7 by specific siRNA could substitute for the effect of chloroquine. No sensitization was seen in nasoepithelial cells.

CONCLUSION

Chloroquine sensitizes nasopharyngeal carcinoma cells but not nasoepithelial cells towards radiation-induced apoptosis by blocking autophagy. Further studies in a mouse-xenograft model are warranted to substantiate this effect in vivo.

Cetuximab induces eme1-mediated DNA repair: a novel mechanism for cetuximab resistance

Overexpression of the epidermal growth factor receptor (EGFR) is observed in a large number of neoplasms. The monoclonal antibody cetuximab/Erbitux is frequently applied to treat EGFR-expressing tumors. However, the application of cetuximab alone or in combination with radio- and/or chemotherapy often yields only little benefit for patients. In the present study, we describe a mechanism that explains resistance of both tumor cell lines and cultured primary human glioma cells to cetuximab. Treatment of these cells with cetuximab promoted DNA synthesis in the absence of increased proliferation, suggesting that DNA repair pathways were activated. Indeed, we observed that cetuximab promoted the activation of the DNA damage response pathway and prevented the degradation of essential meiotic endonuclease 1 homolog 1 (Eme1), a heterodimeric endonuclease involved in DNA repair. The increased levels of Eme1 were necessary for enhanced DNA repair, and the knockdown of Eme1 was sufficient to prevent efficient DNA repair in response to ultraviolet-C light or megavoltage irradiation. These treatments reduced the survival of tumor cells, an effect that was reversed by cetuximab application. Again, this protection was dependent on Eme1. Taken together, these results suggest that cetuximab initiates pathways that result in the stabilization of Eme1, thereby resulting in enhanced DNA repair. Accordingly, cetuximab enhances DNA repair, reducing the effectiveness of DNA-damaging therapies. This aspect should be considered when using cetuximab as an antitumor agent and suggests that Eme1 is a negative predictive marker.

FDG--a marker of tumour hypoxia? A comparison with [18F]fluoromisonidazole and pO2-polarography in metastatic head and neck cancer

PURPOSE

Experimental data suggest that the accumulation of [(18)F]fluorodeoxyglucose (FDG) in malignant tumours is related to regional hypoxia. The aim of this study was to evaluate the clinical potential of FDG positron emission tomography (PET) to assess tumour hypoxia in comparison with [(18)F]fluoromisonidazole (FMISO) PET and pO(2)-polarography.

METHODS

Twenty-four patients with head and neck malignancies underwent FDG PET, FMISO PET, and pO(2)-polarography within 1 week. Parameters of pO(2)-polarography were the relative frequency of pO(2) readings <or=2.5 mmHg, <or=5 mmHg and <or=10 mmHg, respectively, as well as the mean and median pO(2).

RESULTS

We observed a moderate correlation of the maximum standardised uptake value (SUV) of FDG with the tumour to blood ratio of FMISO at 2 h (R=0.53, p<0.05). However, SUV of FDG was similar in hypoxic and normoxic tumours as defined by pO(2)-polarography (6.9+/-3.2 vs 6.2+/-3.0, NS), and the FDG uptake was not correlated with the results of pO(2)-polarography. The retention of FMISO was significantly higher in hypoxic tumours than in normoxic tumours (tumour to muscle ratio at 2 h: 1.8+/-0.4 vs 1.4+/-0.1, p<0.05), and the FMISO tumour to muscle ratio showed a strong correlation with the frequency of pO(2) readings <or=5 mmHg (R=0.80, p<0.001).

CONCLUSION

These results support the hypothesis that tumour hypoxia has an effect on glucose metabolism. However, other factors affecting FDG uptake may be more predominant in chronic hypoxia, and thus FDG PET cannot reliably differentiate hypoxic from normoxic tumours.

Recurrent rectal cancer within the pelvis. A multicenter analysis of 123 patients and recommendations for adjuvant radiotherapy

BACKGROUND AND PURPOSE

Recommendations for radiation ports in adjuvant radiation therapy for rectal cancer are mainly based on analysis of recurrence patterns. To evaluate whether changes in surgical technique have influenced this pattern of recurrence, a multicenter retrospective analysis was carried out on a patient population treated recently.

PATIENTS AND METHODS

123 patients were evaluated with the help of a CT-based self-developed 3-D data file system and an extensive questionnaire. Major inclusion criteria (one sufficient) for eligibility were: histological confirmation, clear bone destruction, and a positive PET scan, or at least three minor criteria: progressive soft tissue mass, invasion of adjacent organs on follow-up CT or MRI, rising tumor markers, and typical appearance in cross-sectional imaging. Clinical or serologic signs of inflammation were exclusion criteria.

RESULTS

Initially, 54% of the evaluated patients were N0; in the remainder, N1 and N2 were distributed evenly. Initial T-category was T1 in 2%, T2 in 24%, T3 in 60%, and T4 in 13%, the male-to-female ratio was 2:1. Recurrent tumors were mainly situated in the posterior part of the bony pelvis as displayed in the figures. When abdominoperineal resection was compared to low anterior resection as primary operation, there was a significant difference in extension of recurrent tumors in the inferior parts of the pelvis (p<0.025 in all statistical tests applied), whereas no significant difference was found in the superior parts of the pelvis.

CONCLUSION

Based on these results, a modest field size reduction in adjuvant radiotherapy for rectal cancer seems feasible, offering the perspective of a reduction in acute and late side effects.

[The time-course of action of rapacuronium and mivacurium after early reversal following equally lasting relaxation]

This study was designed to compare the time course of action and the safety profile of Rapacuronium and Mivacurium in day case dental surgery. After Ethics Committee approval 61 healthy adult patients, scheduled for dental day case surgery, were randomised in an assessor-blinded manner to receive either 1.5 mg/kg Rapacuronium with and without 0.05 neostigmine 5 min later (19 patients each) or a total of 0.25 mg/kg Mivacurium (n = 16). Anaesthesia was induced using Propofol 2 - 5.1 mg/kg and Remifentanil 24 - 73 mcg/kg/h and maintained with Desflurane in N2O/O2 (2/1). Endotracheal intubation was performed when maximum blockade was achieved and scored by a blinded intubator. Neuromuscular block was monitored using the train-of-four response to supramaximal stimuli at the ulnar nerve every 15 seconds using acceleromyography (TOF Watch SX). Onset time, clinical duration (reappearance of the third twitch of a TOF-stimulation) and recovery to T4/T1 > 0.9 were recorded. Speed of recovery was evaluated by the time difference between reappearance of the third twitch and T4/T1 > 0.9. The intubating conditions at the time of maximum block revealed no statistically significant differences between the three groups. Changes in blood pressure, heart rate and airway pressure were not significant. Onset time in subjects who received Rapacuronium (99 +/- 29 s) was faster compared to the onset time in those who received Mivacurium (157 +/- 36 s). Also clinical duration was significantly shorter following Rapacuronium without reversal (12 +/- 4 min) as well as with reversal (9 +/- 1 min) compared with Mivacurium (21 +/- 5 min)). Patients treated with Rapacuronium and reversal recovered faster (14 +/- 8 min)) compared to the other two groups (Mivacurium: 20 +/- 6 min, Rapacuronium without reversal: 31 +/- 9 min). The fraction of clinical duration of the total duration was highest following Mivacurium (51 %) when compared with Rapacuronium/Neostigmine (43 %) and Rapacuronium (28 %).

Radiation-induced leukocyte adhesion to endothelium in normal pancreas and in pancreatic carcinoma of the rat

High-dose radiation is known to induce an inflammatory reaction in normal and malignant tissue including leukocyte infiltration. The influence of radiation on leukocyte-endothelium interaction in tumor tissue, which precedes leukocyte migration, has not yet been investigated to our knowledge. In our study, intravital microscopy was used to compare the radiogenic effects on leukocyte-endothelium interaction and leukocyte migration in healthy and malignant pancreatic tissue in vivo. An established model of ductlike pancreatic cancer (DSL6A) of syngeneic Lewis rats was utilized. Irradiation with 15 Gy increased the high-affinity leukocyte-endothelium interaction both in normal and malignant tissue. The low-affinity leukocyte-endothelium interaction was not significantly altered. Radiation-induced tumor cell death 12 days after radiation was significantly higher in tumors with moderate and severe leukocyte infiltration compared to low leukocyte infiltration. Thus, radiation-induced leukocyte infiltration in pancreatic carcinoma correlates with the extent of tumor cell death.

Inverse automated treatment planning with and without individual optimization in interstitial permanent prostate brachytherapy with high- and low-activity 125I

PURPOSE

To determine whether dose distribution achieved with treatment plans using high- and low-activity (125)I implants differs.

PATIENTS AND METHODS

Based on intraoperative transrectal ultrasound scans of 71 patients, inverse automated treatment plans (IATP) were performed with 15.5-kBq (0.42-mCi) and 25.2-kBq (0.68-mCi) (125)I implants using a commercial 3-D planning system (Variseed). A prescription dose of 145 Gy in 98% of the prostate volume (V100), a maximum dose to the urethra of 250 Gy (D1), and a maximum dose to 10% of the anterior rectal wall of 145 Gy (D10) were required. The plans were manually corrected, if necessary.

RESULTS

In the IATP, a better dose coverage of the prostate was found for high-activity seeds (V100 of 98% vs 84%). The prostate dose values increased with the prostate volume. After manual optimization, the differences were only marginal with a prostate V100 of 99% for both activities, a urethra D1 of 247 Gy and 239 Gy, and a rectum D10 of 135 Gy and 124 Gy for high- and low-activity seeds. Low-activity seeds required more sources (66 vs 47) and needles (24 vs 17; all numbers are median values).

CONCLUSIONS

Concerning the prostate dose coverage, high-activity seeds are superior in the IATP. After manual adjustment, the dose values for the prostate and the organs at risk are similar. Considering a supposedly decreased toxicity and a shorter implantation time for a lower number of seeds, we recommend high-activity seeds for experienced teams.

[Hypofractionated radiation therapy for the treatment of malignant melanoma and squamous cell carcinoma in dogs and cats]

This study describes the experience with hypofractionated radiation therapy of squamous cell carcinoma and melanoma in dogs and cats. A total dose of 32-48 Gray (Gy) was delivered once a week in 8 Gy fractions. 34 animals in which a complete surgical excision was impossible were treated. There was no tumor detectable macroscopically in 14 patients at the beginning of radiation therapy. In 20 animals the median volume of the tumor was 9.9 cm3. The median survival times and the local tumor control of squamous cell carcinoma of the oral and nasal cavities and of the body are comparable to results which were reached with a Monday-Wednesday-Friday scheme. For the treatment of Melanoma the hypofractionated radiation therapy is first choice. There are no significant side effects. Late side effects did not occur. 88% of the owners are satisfied with this kind of treatment and would choose it again.

Endovascular irradiation with the liquid beta-emitter Rhenium-188 to reduce restenosis after experimental wall injury

OBJECTIVE

Postinterventional irradiation is a new therapeutic concept in the prevention of restenosis. The liquid beta-emitter Rhenium-188 allows endovascular brachytherapy using a conventional balloon catheter without the problem of centering the radiation source. In an animal model of restenosis the feasibility and the dose dependent effect of intravascular brachytherapy with a Rhenium-188 filled balloon catheter was investigated.

METHODS

In 68 male New Zealand White rabbits after endothelial denudation of the right common carotid artery with a Fogarty catheter, endovascular irradiation was performed with a Rhenium-188 filled 3.0-mm balloon catheter using different dosages (0, 7.5, 15, 30, 45 and 60 Gy at the surface of the vessel). Then 4 weeks after the intervention the vessels were excised and histologically analyzed.

RESULTS

Whereas at 7.5 Gy the intimal area (median [first quartile; third quartile]) did not differ significantly from the control (0.46 mm(2) [0.33 mm(2), 0.75 mm(2)] vs. 0.49 mm(2) [0.34 mm(2), 0.66 mm(2)]), neointimal hyperplasia was decreased significantly at 15 Gy (0.15 mm(2) [0.04 mm(2), 0.17 mm(2)]) and 30 Gy (0.07 mm(2) [0.04 mm(2), 0. 10 mm(2)]), and completely inhibited at the highest dosages (45 Gy: 0 mm(2) [0 mm(2), 0.04 mm(2)]; 60 Gy: 0 mm(2) [0 mm(2), 0.01 mm(2)]).

CONCLUSIONS

Catheter transmitted endovascular irradiation with the liquid beta-emitter Rhenium-188 after vascular injury is feasible and effectively reduced neointimal hyperplasia in hypercholesterolemic rabbits. A significant reduction of the neointimal formation could be found already at a radiation absorbed dose of 15 Gy at the vessel surface. Following a surface dosage of 45 Gy the proliferative response to the vessel injury is almost completely abolished.

Influence of extracorporeal irradiation on the reintegration of autologous grafts of bone and joint. Study in a canine model

We studied the effects of irradiation on the reintegration of autologous osteoarticular grafts over a period of 24 weeks in a canine model. In 16 foxhounds the medial femoral condyle was resected, irradiated and immediately replanted. In the control group resection and replantation were performed without irradiation. Reintegration was assessed by macroscopic analysis, histology, radiography and gait analysis. Reintegration was equal at 12 weeks, but significantly inferior in the irradiated group after 24 weeks with delayed bone remodelling. The articular cartilage showed modest degeneration. Conventional radiography and histology showed corresponding changes. Limb function was adequate but the gait was inferior in the treated group.

Influence of extracorporeal irradiation on the reintegration of autologous grafts of bone and joint

We studied the effects of irradiation on the reintegration of autologous osteoarticular grafts over a period of 24 weeks in a canine model. In 16 foxhounds the medial femoral condyle was resected, irradiated and immediately replanted. In the control group resection and replantation were performed without irradiation. Reintegration was assessed by macroscopic analysis, histology, radiography and gait analysis.

Reintegration was equal at 12 weeks, but significantly inferior in the irradiated group after 24 weeks with delayed bone remodelling. The articular cartilage showed modest degeneration. Conventional radiography and histology showed corresponding changes. Limb function was adequate but the gait was inferior in the treated group.

[Intraoperative extracorporeal irradiation and replantation (EIR) in the treatment of primary malignant bone tumors]

In 6 patients with primary malignant bone tumors (4 Ewing, 1 recurrent Adamantinoma, 1 maligne Haemangioperizytoma) the local therapy was performed as intraoperative extracorporeal irradiation and replantation. During the follow-up 10 (6-24) months no local recurrence in the replanted segment occurred. One recurrence occurred in the host bed; in two cases the replanted segment had to be removed because of severe infection. The other cases showed good functional and radiological results. These clinical findings and the reports in the literature seem to allow the application of the intraoperative extracorporeal irradiation and replantation procedure for defect reconstruction in cases of chemo- and radiotherapy-sensitive bone tumors.

[Morbidity and tumor control in limb-saving resection with intraoperative radiotherapy in a multimodality therapy concept in soft tissue sarcoma]

This study evaluates limb-saving surgery (LSS) combined with intraoperative radiotherapy (IORT) and external beam radiotherapy (EBRT) for extremity sarcoma. Prospectively gathered data was analyzed for 50 patients. Advanced stages (UICC IIB-IIIB) predominated (80%) and 50% of the tumors were recurrent. Early local morbidity amounted to 32%, including wound infection (6), skin necrosis (3), hematoma (3) and others (4). Late morbidity of 10% consisted of a fracture, a fibrosis, two chronic lymphedemas and a neuropathy. One patient died (pulmonary embolism). Local control was obtained in 91% with an overall 3-year survival rate of 81% in cases treated with curative intent (follow-up 29 months). No survival benefit was found for patients with microscopically clear margins; however, local failure occurred less frequently (p = 0.02). Our results support the use of LSS with IORT and EBRT for extremity sarcoma and emphasize the importance of the surgical margin.

Radiosensitizing potential of gemcitabine (2',2'-difluoro-2'-deoxycytidine) within the cell cycle in vitro

PURPOSE

Gemcitabine (2',2'-difluorodeoxycytidine; dFdCyd) is a new deoxycitidine analog which exhibits substantial activity against solid tumors and radiosensitizing properties in vitro. To examine cell cycle-specific effects of a combined treatment with gemcitabine and radiation, the in vitro clonogenic survival of two different cell lines was measured for cells from log-phase culture, G1 and S-phase cells.

METHODS AND MATERIALS

Chinese hamster (V79) and human colon carcinoma (Widr) cells were exposed to different radiation doses and for different points of time relative to gemcitabine treatment (2 h). Experiments were also carried out with different cell-cycle populations obtained after mitotic selection (V79) or after serum stimulation of plateau-phase cells (Widr). The resulting survival curves were analyzed according to the LQ model, and mean inactivation doses (MID) and the cell cycle-specific enhancement ratios (ER) were calculated from the survival curve parameters.

RESULTS

Effectiveness of combined treatment of log-phase cells was greatest when cells were irradiated at the end of the gemcitabine exposure [ER: 1.28 (V79), 1.24 (Widr)]. For later times after the removal of the drug, radiosensitization declined, approaching independent toxicity. From the time course of interactive-type damage decay half-life values of 75 min (V79) and 92 min (Widr) were derived. Gemcitabine did not radiosensitize G1 Widr cells or V79 cells from the G1/S border, but substantial radiosensitization was observed for the S-phase cell preparations [ER: 1.45 (V79-lateS), 1.57 (Widr)].

CONCLUSIONS

Treatment of cells with gemcitabine immediately before irradiation eliminates, or at least greatly reduces, the variation in radiosensitivity during the cell cycle that is manifested by radioresistance during S phase. This reversal of S-phase radioresistance could imply that gemcitabine interferes with the potentially lethal damage repair/fixation pathway. Other approaches have been taken to overcome S-phase radioresistance, such as hyperthermia or densely ionizing radiation, and combined treatments with dFdCyd could prove of value to complement such efforts.

Long-term response to crisnatol mesylate in patients with glioma

A total of 26 patients (6 with anaplastic astrocytoma; 20 with glioblastoma) were treated with crisnatol mesylate. All patients had residual or progressive disease following surgery and standard radiotherapy; nine patients had prior chemotherapy. Crisnatol was administered as a 72-hour infusion every 21 days at a starting dose of 2250 mg/m2. Two patients who had not received prior chemotherapy achieved a complete response and remain in continuous complete remission over seven and six years, respectively, post-diagnosis. Two other patients remained stable on crisnatol for 10 months before disease progression. One patient with mixed oligodendroglioma/glioblastoma progressed after 12 months on crisnatol. He survives at 7 years post-diagnosis, with Karnofsky Performance Status of 60 following other therapies. One patient with anaplastic astrocytoma stopped treatment by request after 10 months and remains stable 64 months post diagnosis. Seventeen evaluable patients, including nine patients with prior chemotherapy, progressed after 2-9 courses of therapy. Median survival is 9.25 months, with a one year survival rate of 30% and 2 years survival rate of 17%. Neurotoxicity was acute and dose-limiting. Side effects were tolerable and limited to duration of infusion. Two complete, long-lasting responses to crisnatol mesylate in patients with progressive malignant glioma are encouraging results and warrant further investigation.

[Intraoperative radiotherapy in advanced soft tissue sarcoma of the extremities]

Radical or wide excision is the treatment of choice for soft-tissue sarcomas (STS) of the extremities. Multimodality therapy made limb-sparing surgery possible. While external beam radiotherapy is well established in this setting, few data are available about intraoperative radiotherapy (IORT). We performed an analysis of 36 patients treated with IORT and external beam radiation following resection of STS of the extremities between 1991 and 1995. Only STS classified as UICC stage IIb, III or IV were included. Operative morbidity was 17%, 14% showed late complications. Within a mean follow-up of 24 months (min. 6), there was one local recurrence in 30 patients treated curatively. The 3-year survival rate of patients treated curatively was 75%; 3-year recurrence-free survival was 65%.

Additive effects of cisplatin and radiation in human tumor cells under oxic conditions

The interaction of cisplatin and irradiation was studied in vitro in four human cell lines. Additive effects were observed for the combination given either simultaneously or sequentially. No influence on recovery was seen in split-dose experiments. It is concluded that radiosensitization cannot be presumed in every clinical setting of combined treatment with radiation and cisplatin.

[Effects of lonidamine alone or in combination with radiotherapy on survival and metabolism in human and rodent cell lines]

In vitro investigations on the combined effect of radiation and Lonidamine in one human (LXI) and two rodent cell lines (3T3, V79) showed not a clear radiosensitizing effect. Especially no inhibiting influence on the repair of potentially lethal damage of V79 cells was found. Incubation at lower pH values (6.7 to 6.9) caused no increasing effects. Lonidamine induced damage on the mitochondrial dehydrogenase-system was quantitatively measured with a modified MTT-assay.

Mitoxantrone: a novel anthracycline derivative

The chemistry, pharmacology, pharmacokinetics, clinical efficacy, dosage and administration, and adverse effects of mitoxantrone are reviewed. Mitoxantrone, an aminoanthraquinone that was synthesized in 1979, belongs to a new chemical class of agents known as the anthracenediones. It possesses antiviral, antibacterial, immunomodulatory, and antitumor activity. The drug's antitumor activity is attributed to its interaction with DNA topoisomerase II, and its interaction with human cells may also involve nonintercalary, electrostatic interactions. Mitoxantrone is poorly absorbed orally and is most commonly administered intravenously. The drug is rapidly distributed into the red blood cells, white blood cells, and platelets, followed by deep-tissue sequestration. Mitoxantrone has demonstrated clinical efficacy in the treatment of leukemia, lymphoma, and breast cancer. As a single agent, mitoxantrone has a response rate of roughly 30% in acute nonlymphocytic leukemia or acute myeloid leukemia. In combination with other standard agents (cytarabine, vincristine, and prednisone), the response rate may reach 60%. In breast cancer, mitoxantrone's response rate as a single agent is 25-30%, while combination regimens produce response rates of 60% or more. The drug can cause cardiotoxicity with cumulative doses. Other adverse effects include myelosuppression, nausea and vomiting, stomatitis, mucositis, and alopecia. The cost of mitoxantrone is comparable to that of doxorubicin, but it is substantially more expensive than daunorubicin. Mitoxantrone is an important new agent with antitumor activity in leukemia, lymphoma, and breast cancer. In most situations, mitoxantrone will be considered second-line treatment or a restricted-use item because of its high cost and because of the lack of FDA approval for indications other than acute nonlymphocytic leukemia.