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C B Ostertag

Publications and source records attributed to C B Ostertag.

At least 19 recordsLinked to original sources
PubMed1997

Supratentorial World Health Organization Grade 2 astrocytomas and oligoastrocytomas. A new pattern of prognostic factors.

BACKGROUND: Prognostic factors for adult patients with supratentorial World Health Organization (WHO) Grade 2 astrocytomas and poorly defined. METHODS: The prognostic importance of pretreatment patient- and tumor-related factors was analyzed retrospectively in 197 adult patients with supratentorial astrocytomas (n = 153) or oligoastrocytomas (n = 44) using the multivariate Cox proportional hazards model. Endpoints were death and date of malignant transformation. All patients were treated similarly between 1979 and 1992 with iodine-125 implants as the primary treatment. RESULTS: A new prognostic pattern was detected. Unfavorable prognostic factors with regard to survival were 1) a tumor volume > or = 20 mL; 2) a performance status < or = 80; and 3) age > or = 40 years for the female subpopulation. Midline shift (another important tumor-related factor after univariate analysis) was highly correlated with tumor volume and therefore not included in the multivariate model. Risk factors of malignant transformation were 1) a tumor volume > or = 20 mL; 2) an enhancement in the computed tomography scan; and 3) age > or = 40 years for the female subpopulation. Prognostic factors created subsets of patients with 5-year survival rates ranging from as low as 5% to as high as 79%. CONCLUSIONS: Any treatment decision or evaluation of treatment efficacy should take into account the strong influence of both patient- and tumor-related factors. Any further study design should consider the detected interaction between gender and age and the importance of tumor volume.

Adult↗
PubMed1996

Stereotactic management of lesions of the pineal region.

OBJECTIVE: The relevance of the computed tomography-guided stereotactic approach for the management of lesions of the pineal region is analyzed. METHODS: In a retrospective analysis conducted between 1985 and 1993, the risk profile, the diagnostic accuracy, and the therapeutic relevance of the stereotactic approach in 106 patients was studied. Survival analysis was used to assess the reliability of the stereotactically obtained diagnosis in terms of follow-up observation. RESULTS: A histological diagnosis was obtained in 103 of the 106 patients. In three patients, a conclusive diagnosis could not be established because of intraoperative complications. One lesion was misdiagnosed as a pineocytoma instead of a pineoblastoma. Two of the 106 patients died; 9 patients experienced perioperative morbidity. In 38 patients, the stereotactic approach was also useful for therapy. Cyst aspiration and/or internal drainage was performed in 18 patients with symptomatic cystic lesions, and radiosurgical treatment with use of interstitial 125iodine was performed in 16 patients with low-grade tumors and in 4 patients with solitary metastases. In 12 patients, the obtained tissue diagnosis was the basis for deferring additional therapy. In 43 patients with germ-cell tumors, pineoblastomas, or malignant gliomas, a stereotactic biopsy was the starting point for additional radiotherapy/chemotherapy. Open tumor resection played a minor role (five patients). CONCLUSION: The stereotactic approach to the pineal region is a relatively safe procedure in experienced hands. The diagnosis obtained by computed tomography-guided stereotactic biopsy is a valid basis for treatment decisions. Long-term follow-up observation of the benign lesions is necessary for a definite confirmation of diagnostic accuracy.

Adolescent↗
PubMed1995

Interstitial iodine-125 radiosurgery for cerebral metastases.

The current study evaluates the efficacy of interstitial 125-iodine radiosurgery (brachytherapy) in 93 patients with circumscribed, spherical, mostly solitary metastases. In all patients the histological diagnosis was established by stereotactic biopsy. The treatment results of three therapeutic regimens have been examined retrospectively: Group A (38 patients) had interstitial radiosurgery with a reference tumour dose of 60 Gy in combination with percutaneous radiotherapy (40 Gy). Group B (34 patients) was treated by interstitial radiosurgery alone (reference dose 60 Gy). Group C (21 patients with recurrent metastases after previous radiotherapy/surgery) was treated by interstitial radiosurgery alone (reference dose 60 Gy). Median survival after interstitial radiosurgery was 17 months in group A, 15 months in group B, 6 months in group C. Favourable prognostic factors were a Karnofsky performance rating > or = 70, solitary metastasis, absence of disseminated disease, and a time interval > 1 year between diagnosis of the primary tumour and diagnosis of the cerebral metastases. Interstitial radiosurgery plus percutaneous radiotherapy did not prove to be superior to interstitial radiosurgery alone. No patient died of a locally irradiated metastasis. We conclude that interstitial radiosurgery achieves control of the growth of solitary spherical cerebral metastases in any location without radiation toxicity.

Adult↗
PubMed1995

Interstitial radiosurgery of low-grade gliomas.

The treatment of patients with low-grade gliomas remains a subject of controversy, especially with respect to new treatment modalities such as interstitial radiosurgery (brachytherapy), radiosurgery, and stereotactic radiotherapy. In a retrospective analysis conducted between 1979 and 1991, the authors studied the results of interstitial radiosurgery in 455 patients with low-grade gliomas (World Health Organization (WHO) Grade I+WHO Grade II) with regard to survival time, quality of life, the risk of malignant transformation, and the risk profile of the treatment concept. Interstitial radiosurgery with iodine-125 was performed using permanent (1979-1985) or temporary implants (after 1985) with low-dose rates (< or = 10 cGy/hr) and a reference dose of 60 to 100 Gy calculated to the outer rim of the tumor. The 5- and 10-year survival rates in patients with pilocytic astrocytomas (97 patients) were 84.9% and 83%, and in patients with WHO Grade II astrocytomas (250 patients) 61% and 51%, respectively. Five-year survival rates for patients with oligoastrocytomas (60 patients), oligodendrogliomas (27 patients), and gemistocytic astrocytomas (21 patients) were 49%, 50%, and 32%, respectively. In the group with WHO Grade II gliomas, young age and a good performance status were associated with a better prognosis. Unfavorable factors were midline shift, enhancement on computerized tomography (CT) scan, and tumor recurrence after previous radiotherapy or surgery. Tumor location had no influence on the prognosis (247 patients in this series had deep-seated tumors). Malignant transformation was the major cause of death. Important risk factors for malignancy were the patient's age, tumor enhancement in CT scan, and tumor recurrence after previous surgery or radiotherapy. Perioperative mortality was 0.9% and perioperative morbidity was 1.7%. Radiogenic complications were observed in 2.7% of all patients, most often in larger tumors and after using permanent implants. The authors conclude that interstitial radiosurgery represents a specific treatment modality for selected patients with unifocal circumscribed low-grade gliomas with a diameter of less than 4 cm in any location. The efficacy of this treatment lies in the same range as the best results after surgery and radiotherapy.

Adolescent↗
PubMed1994

Simultaneous measurement of bidirectional capillary permeability, vascular volume, extracellular space, and rCBF in experimental gliomas and surrounding edema.

Measurements of bidirectional capillary permeability in the ASV tumor model revealed a heterogeneous distribution of transport rates for the small water-soluble molecules which are believed to be the driving force in perifocal edema formation. Mean K1 values were 8.1 +/- 5.5 microliters/g/min in whole tumor and 18.89 +/- 12.3 microliters/g/min in highly permeable areas. Tumor blood flow ranged between normal white matter and cortex, whereas the plasma vascular space in the tumors was increased as compared to the normal brain. The size of the extracellular space was depending on the regional capillary permeability, underlining the vasogenic nature of peritumoral edema which was capable of being studied using in vivo methods.

Animals↗
PubMed1994

Interstitial 125-iodine radiosurgery of low-grade gliomas of the insula of Reil.

Between 1979 and 1991 67 patients with low-grade gliomas of the insula (of Reil) were treated with 125-iodine interstitial radiosurgery. Retrospective analysis with a median follow-up of 55 months demonstrated a 5- and 10-year survival rate of 54% and 47%, respectively, for all low-grade gliomas treated and a 5- and 10-year survival rate of 57% for 49 patients with astrocytomas WHO grade II analysed separately. The median Karnofsky performance status of survivors was 90%. Malignant change was the cause of death in 85%, failure to control tumour growth in the remaining cases. Multivariate analysis with a Cox proportional hazard model identified solely the pre-operative Karnofsky performance score of 70-80 vs. 90% as a prognostic factor for outcome (p = 0.001, risk ratio 3.62), but not age, gender, tumour volume, length of disease before treatment, mode of implantation, or major vs. moderate or no shrinkage of tumour volume after interstitial radiosurgery. Thus, 125-iodine radiosurgery yielded survival rates in these deep-seated insular gliomas comparable to those reported after surgery and radiation therapy of lobar tumours. This was achieved with a low peri-operative mortality and morbidity and at low costs.

Adolescent↗
PubMed1994

Stereotactic radiation therapy and radiosurgery.

In all stereotactic irradiation procedures, a high dose is delivered to a relatively small target volume. Whether fractionated stereotactic radiotherapy is preferable (based on a therapeutic ratio) or a radiosurgical method (aiming at the precise and complete destruction of a tissue volume) depends on the definition and composition of the target. The methodologies can be grouped in closed-skull external focussed beam stereotactic radiosurgery/radiotherapy and in stereotactic implantation/injection of radiation sources. Although originally developed to treat functional disorders of the brain, stereotactic radiosurgery has been used most successfully for over 4 decades to treat cerebral arteriovenous malformations. Complete obliteration ranges from 30 to 50% after 1 year are reported. At 2 years the results range from 72 to 90%. Clearly the outcome is influenced by patient selection. In the treatment of acoustic neurinomas follow-up data of larger series of radiosurgery show that the treatment performed under local anesthesia on an outpatient basis becomes comparable with the best microsurgery data. Using multiple isocenters and MR localization tumor growth control is achieved in more than 90% of cases, with hearing preservation of approximately 50%. Pituitary tumors with Cushing's syndrome, acromegaly, Nelson's syndrome, prolactinomas and nonsecreting adenomas have been treated with various stereotactic irradiation methods. Further refinement of both localization techniques, dose distribution and beam manipulation will make radiosurgery an attractive modality because of its noninvasive character and low morbidity. Only a small subgroup of patients with low-grade gliomas are candidates for stereotactic localized irradiation treatment, namely those with circumscribed tumors with only limited spread of tumor cells into the periphery. For this subgroup, which usually comprises not more than 25% of all low-grade gliomas, the results from interstitial radiosurgery compete with surgical resection. Apart from the possibility to define the borders of the treatment volume with serial stereotactic biopsies, there are dosimetric advantages of interstitial radiosurgery. Local single high-dose treatment remains controversial for highly malignant infiltrative tumors, and significant treatment benefit remains to be documented. Radiosurgery can be used to effectively treat solitary brain metastases with less invasiveness and dissection of normal tissue, and with lower morbidity and less expense than open surgery.

Brain Neoplasms↗