Purpose: In oncological orthopedics, navigation systems are limited to use in specialized centers, because specific, expensive, software is necessary. To resolve this problem, we present a technique using general spine navigation software to resect tumors located in different segments. Materials and Methods: This technique requires a primary surgery during which screws are inserted in the segment where the bone tumor is; next, a CT scan of the entire segment is used as a guide in a second surgery where a resection is performed under navigation control. We applied this technique in four selected cases. To evaluate the procedure, we considered resolution obtained, quality of the margin and its control. Results: In all cases, 1 mm resolution was obtained; navigation allowed perfect control of the osteotomies, reaching the minimum wide margin when desired. No complications were reported and all patients were free of disease at follow-up (average 25.5 months). Conclusions: This technique allows any bone segment to be recognized by the navigation system thanks to the introduction of screws as landmarks. The minimum number of screws required is four, but the higher the number of screws, the greater the accuracy and resolution. In our experience, five landmarks, placed distant from one another, is a good compromise. Possible disadvantages include the necessity to perform two surgeries and the need of a major surgical exposure; nevertheless, in our opinion, the advantages of better margin control justify the application of this technique in centers where an intraoperative CT scanner, synchronized with a navigation system or a dedicated software for bone tumor removal were not available.

Background: The complexity of neurosurgical interventions demands innovative training solutions and standardized evaluation methods that in recent times have been the object of increased research interest. The objective is to establish an education curriculum on a phantom‑based training system incorporating theoretical and practical components for important aspects of brain tumor surgery. Methods: Training covers surgical planning of the optimal access path based on real patient data, setup of the navigation system including phantom registration and navigated craniotomy with real instruments. Nine residents from different education levels carried out three simulations on different data sets with varying tumor locations. Trainings were evaluated by a specialist using a uniform score system assessing tumor identification, registration accuracy, injured structures, planning and execution accuracy, tumor accessibility and required time. Results: Average scores improved from 16.9 to 20.4 between first and third training. Average time to craniotomy improved from 28.97 to 21.07 min, average time to suture improved from 37.83 to 27.47 min. Significant correlations were found between time to craniotomy and number of training (P < 0.05), between time to suture and number of training (P < 0.05) as well as between score and number of training (P < 0.01). Conclusion: The training system is evaluated to be a suitable training tool for residents to become familiar with the complex procedures of autonomous neurosurgical planning and conducting of craniotomies in tumor surgeries. Becoming more confident is supposed to result in less error‑prone and faster operation procedures and thus is a benefit for both physicians and patients.

When removal of primary tumors is performed by surgery, the surgeon andthe patient would benefit from using intraoperative feedback to evaluate thetumor resection margin. If intraoperative feedback is not provided there isadditional risk of treatment of the tumor. With improvements to the fixationtime of soft tissue, phase-contrast computed tomography (PC-CT) could allow3D intraoperative feedback to the surgeons.The focus of this project has been to develop a method for measuring fixationtime on soft tissue samples and examine ways to decrease the required fixationtime. Furthermore, evaluation of fixatives to achieve image contrast that wouldbe sufficient to accomplish the possibility of intraoperative tumor feedback, inPC-CT images has been performed in this project. / När avlägsnande av primära tumörer utförs av kirurger, skulle både kirurgenoch patienten gynnas av intraoperativ återkoppling för att bedöma resektions-marginalen. Utan intraoperativ återkoppling finns det risk för att yttrligarebehandling av tumören är nödvändig. Med förbättringar inom fixeringstid avmjukvävnad skulle faskontrast-CT möjliggöra 3D intraoperativ återkopplingtill kirurgen.Fokuset inom detta projekt har varit att ta fram en metod för mätning av fixe-ringstid av mjukvävnadsprover och undersöka tillvägagångssätt för att minskaden behövda fixeringstiden. Vidare så har utvärdering av fixeringsvätskor föratt uppnå bildkontrast som skulle vara bra nog att fungera som intraoperativåterkoppling av tumör-information, inom faskontrast-CT utförts i detta projekt.

Background: The complexity of neurosurgical interventions demands innovative training solutions and standardized evaluation methods that in recent times have been the object of increased research interest. The objective is to establish an education curriculum on a phantom‑based training system incorporating theoretical and practical components for important aspects of brain tumor surgery. Methods: Training covers surgical planning of the optimal access path based on real patient data, setup of the navigation system including phantom registration and navigated craniotomy with real instruments. Nine residents from different education levels carried out three simulations on different data sets with varying tumor locations. Trainings were evaluated by a specialist using a uniform score system assessing tumor identification, registration accuracy, injured structures, planning and execution accuracy, tumor accessibility and required time. Results: Average scores improved from 16.9 to 20.4 between first and third training. Average time to craniotomy improved from 28.97 to 21.07 min, average time to suture improved from 37.83 to 27.47 min. Significant correlations were found between time to craniotomy and number of training (P < 0.05), between time to suture and number of training (P < 0.05) as well as between score and number of training (P < 0.01). Conclusion: The training system is evaluated to be a suitable training tool for residents to become familiar with the complex procedures of autonomous neurosurgical planning and conducting of craniotomies in tumor surgeries. Becoming more confident is supposed to result in less error‑prone and faster operation procedures and thus is a benefit for both physicians and patients.

Patienten mit metastasierten Keimzelltumoren, die einen Progress oder ein Rezidiv ihrer Erkrankung nach einer cisplatinhaltigen Vortherapie erleiden, haben eine schlechte Prognose. Unter Verwendung einer erneuten konventionellen Chemotherapie können maximal 15-30% dieser Patienten geheilt werden, so dass die Mehrzahl der Patienten an ihrer Erkrankung verstirbt. Aus diesem Grund ist die Optimierung der therapeutischen Möglichkeiten ein wesentliches Ziel. Unsere Daten zeigen, dass die Hochdosischemotherapie (HDCT) eine wesentliche therapeutische Verbesserung darstellt und mittels dieser Therapie mit einem ereignisfreien Überleben von 30-60% zu rechnen ist. Eine "matched-pair" Analyse konnte im Hinblick auf das ereignisefreie und das Gesamtüberleben einen Vorteil von mehr als 10% zu Gunsten der HDCT feststellen. Darüber hinaus hat die zunehmende Erfahrung und die Verwendung von peripheren Blutstammzellen und hämatopoetischen Wachstumsfaktoren, den Einsatz der HDCT deutlich sicherer gemacht. Aus den genannten Gründen sollte alle Patienten mit Rezidiv oder Progress eines Keimzelltumors der HDCT zugeführt werden. Die operative Entfernung von residuellen Tumormanifestationen (RTR) nach primärere Chemotherapie ist heute Standard bei Patienten mit metastasierten Keimzelltumoren. Zwar findet sich in der histologischen Aufarbeitung bei den meisten Patienten ausschließlich nekrotisches Gewebe, doch werden bei einem Teil der Patienten auch Anteile von reifem Teratom und vitalen differenzierten und undifferenzierten Karzinomen gefunden. Während die Resektion von Nekrose keinen therapeutischen Benefit für den Patienten darstellt, ist die komplette Entfernung von reifem Teratom oder Zellen eines Karzinoms für die Prognose entscheidend. In Bezug auf die HDCT konnten bisher keine vergleichbaren Daten erhoben werden. Zur Evaluierung des Stellenwertes der RTR nach HDCT analysierten wir unser eigenes Patientenkollektiv und fanden, dass vergleichbar zur Primärtherapie alle Patienten nach Salvage-HDCT, die eine partielle markernegative oder markerpositive Remission erreicht haben, einer RTR zugeführt werden sollten. Bis auf intrazerebrale Reste sollten alle residuellen Tumormanifestationen komplett reseziert werden. Neben der Optimierung der therapeutischen Möglichkeiten ist auch die Minimierung der chemotherapieassoziierten Toxizitäten ein wesentlicher Bestandteil meiner wissenschaftlichen Arbeit. Aus diesem Grund evaluierten wir die Wirksamkeit der Substanz Amifostin im Hinblick auf die Verringerung von Toxizitäten, die Wirkung auf die Mobilisierung von peripheren Blutstammzellen und den Einfluß auf die Rekonstitution des Immunstatus bei Patienten mit rezidivierten oder progredienten Keimzelltumoren, die mittels einer konventionellen Chemotherapie und anschließender HDCT behandelt wurden. Der Einsatz von Amifostin erbrachte in diesem Zusammenhang und in diesem Patientenkollektiv keinen therapeutischen oder prophylaktischen Nutzen, so dass dessen Verwendung bei Patienten mit Keimzelltumoren nicht generell empfohlen werden kann. / Overall, patients with relapsed or progressive germ cell tumors (GCT) after cisplatin-based chemotherapy have a low chance of cure. Using conventional-dose chemotherapy as salvage treatment only 15-30% of the patients will become long-term survivors. It is well known that the majority of these patients will ultimately die of their disease. Therefore, improvment of standard treatment is clearly desirable. Our data has been established high-dose chemotherapy (HDCT) as an effective salvage modality with an event-free survival of 30-60%. A matched-pair analysis showed an advantage for HDCT compared with conventional-dose chemotherapy with improvement in event-free and overall survival of more than 10%. Furthermore, due to increasing clinical experience in the management of side-effects, the use of peripheral blood progenitor cells, and the availability of hematopoietic growth factors, HDCT has become relatively safe. In GCT patients with relapsed or rogressive disease HDCT has been demonstrated as a feasible and safe treatment concept which will be curative for a substantial proportion of these patients. Therefore, HDCT should be administered in patients with first relapse and unfavorable prognostic factors and as second or subsequent salvage treatment. Surgical resection of residual tumors (RTR) after first-line chemotherapy is recommended in patients with metastatic GCT. Necrosis will be the only histological finding in the majority of these patients. However, in others mature teratoma, viable cancer consisting of residual GCT, non germ-cell tumors, undifferentiated cancer or a combination of these histologies may be found. Whereas the resection of necrosis offers no therapeutic benefit, resection of mature teratoma or viable cancer adds to long-term event-free and overall survival in these patients. However, limited data exist on the results of surgery and the respective histologies in patients after first or subsequent salvage treatment with HDCT. To assess the contribution of RTR in this setting, we retrospectively analyzed a cohort of patients who had been treated with HDCT for relapsed or refractory GCT. Our data show that RTR contributes to the overall treatment outcome and should be offered to all patients with a partial remission after HDCT. Complete resections of all residual tumors outside the CNS should be attempted. Furthermore, we assessed the efficacy of amifostine for protection from chemotherapy-induced toxicities, for peripheral blood progenitor cell mobilization and for immune-reconstitution in patients treated with conventional-dose paclitaxel, ifosfamide, cisplatin (TIP) and high-dose carboplatin, etoposide and thiotepa (CET) followed by PBPC rescue. In conclusion, amifostine additional to conventional-dose chemotherapy or HDCT showed no unequivocal advantage in protection from treatment-related toxicities and had no effect neither on PBPC mobilization nor on immune-reconstitution.

Pilocytic astrocytoma (PA) is the most common brain tumor in children. This tumor is usually benign and has a good prognosis. Total resection is the treatment of choice and will cure the majority of patients. However, often only partial resection is possible due to the location of the tumor. In that case, spontaneous regression, regrowth, or progression to a more aggressive form have been observed. The dependency between the residual tumor size and spontaneous regression is not understood yet. Therefore, the prognosis is largely unpredictable and there is controversy regarding the management of patients for whom complete resection cannot be achieved. Strategies span from pure observation (wait and see) to combinations of surgery, adjuvant chemotherapy, and radiotherapy. Here, we introduce a mathematical model to investigate the growth and progression behavior of PA. In particular, we propose a Markov chain model incorporating cell proliferation and death as well as mutations. Our model analysis shows that the tumor behavior after partial resection is essentially determined by a risk coefficient γ, which can be deduced from epidemiological data about PA. Our results quantitatively predict the regression probability of a partially resected benign PA given the residual tumor size and lead to the hypothesis that this dependency is linear, implying that removing any amount of tumor mass will improve prognosis. This finding stands in contrast to diffuse malignant glioma where an extent of resection threshold has been experimentally shown, below which no benefit for survival is expected. These results have important implications for future therapeutic studies in PA that should include residual tumor volume as a prognostic factor.

Pilocytic astrocytoma (PA) is the most common brain tumor in children. This tumor is usually benign and has a good prognosis. Total resection is the treatment of choice and will cure the majority of patients. However, often only partial resection is possible due to the location of the tumor. In that case, spontaneous regression, regrowth, or progression to a more aggressive form have been observed. The dependency between the residual tumor size and spontaneous regression is not understood yet. Therefore, the prognosis is largely unpredictable and there is controversy regarding the management of patients for whom complete resection cannot be achieved. Strategies span from pure observation (wait and see) to combinations of surgery, adjuvant chemotherapy, and radiotherapy. Here, we introduce a mathematical model to investigate the growth and progression behavior of PA. In particular, we propose a Markov chain model incorporating cell proliferation and death as well as mutations. Our model analysis shows that the tumor behavior after partial resection is essentially determined by a risk coefficient γ, which can be deduced from epidemiological data about PA. Our results quantitatively predict the regression probability of a partially resected benign PA given the residual tumor size and lead to the hypothesis that this dependency is linear, implying that removing any amount of tumor mass will improve prognosis. This finding stands in contrast to diffuse malignant glioma where an extent of resection threshold has been experimentally shown, below which no benefit for survival is expected. These results have important implications for future therapeutic studies in PA that should include residual tumor volume as a prognostic factor.