Combined treatment of fourth ventricle ependymomas: report of 26 cases

BACKGROUND

This study investigated the relevance of prognostic factors and the impact of histological features in posterior fossa ependymoma.

METHODS

The charts of 26 patients (aged 1-59 years, mean 20.6 years; 11 adults) with posterior fossa ependymoma operated on between January 1983 and December 1994 were reviewed and patients followed up (mean: 93 months).

RESULTS

Gross total resection was performed in 18 patients (69%), subtotal in seven patients (27%), biopsy in one patient (4%). One patient (3.8%) developed respiratory complications and died. All patients underwent posterior fossa radiotherapy (5000 cGy) after surgery. Four children first received chemotherapy and then radiotherapy only when at least 3 years old. Eleven patients (42%) received radiotherapy and subsequently chemotherapy. The 5-year survival rate was 90% for adults and 40% for children (</= 6 years).

CONCLUSIONS

This review suggests that a) younger patients (</= 6 years), despite multimodality treatment, have a poor prognosis; b) the microanatomical location of the tumor (lateral recess, roof, and floor) influences the extent of tumor removal (p < 0.05); c) longer survivals are associated with complete removal (p < 0.05); d) the histological feature most often related to a poor prognosis is a high mitotic index (p < 0.05), whereas vascular proliferation (p = 0.149), necrosis (p = 0.215), nuclear atypia (p = 0.384) and high cellularity (p = 0.786) do not affect survival; e) histological classification (WHO) does not reflect different survival rates between ependymomas and anaplastic ependymomas (p = 0.082).

T classification and clivus margin as risk factors for determining locoregional control by radiotherapy of nasopharyngeal carcinoma

BACKGROUND

The purpose of this study was to determine risk factors that affect locoregional control of nasopharyngeal carcinoma (NPC) after radiotherapy. Computed tomography (CT) is utilized for radiotherapy planning and for identifying high risk anatomic areas.

METHODS

Between April 1990 and December 1993, 40 consecutive patients (1 in Stage I, 3 in Stage II, 5 in Stage III, and 31 in Stage IV) who had locoregional NPC were given definitive radiotherapy at the Koo Foundation Sun Yat-Sen Cancer Center in Taipei, Taiwan. All patients had individualized CT treatment planning. The dimension of each tumor as shown on the treatment planning CT were mapped on conventional simulation films. The extent of each tumor was further affirmed by magnetic resonance imaging (MRI) and the tumor map revised as necessary. The primary radiation fields were designed to include the primary tumor and potential spread areas with appropriate margins. Concurrent chemotherapy was also given to 35 patients (87.5%) who had positive cervical lymph nodes or primary tumors extending beyond the nasopharynx.

RESULTS

By the end of December 1995, after a median follow-up of 42 months and minimal follow-up of 24 months, the locoregional control rate at 4 years was 84.8% (95% confidence interval [CI], 72.3-97.3), disease free survival 68.4% (95% CI, 52. 1-84.7), and overall survival 76.7% (95% CI, 63.4-90.0). The radiation field margin near the sphenoid sinus averaged 1.9 cm, the clivus margin 1.1 cm, the pterygoid fossa margin 2.0 cm, and the oral cavity margin 1.7 cm. Risk factor analysis revealed that T classification and the radiation field margin at the clivus were the most important factors for locoregional control of the tumor. The locoregional control rates were 92.6% (25/27) for T1-T3 patients and 76.9% (10/13) for T4 patients (P = 0.03). The locoregional control rates were 71.4% (5/7) for patients with a clivus margin < 1 cm and 90.6% (29/32) for patients with a clivus margin > or = 1 cm (P = 0.08).

CONCLUSIONS

The excellent locoregional control observed in this series may be attributed to the concurrent chemotherapy and radiotherapy as well as meticulous treatment planning with CT and MRI. The precise delineation of the involved area with the aid of CT, which is taken while the patient is in the position for irradiation, serves to define the necessary safety margin of the radiation field. T classification and clivus margin are the most important factors in determining locoregional control of radiotherapy of NPC. The statistical trend observed in this study indicated that the clivus margin should be adequate to reduce the failure around the clivus, as all local recurrences were observed in this area.

Radiation-induced glioma of the spinal cord

We report a case of a radiation-induced spinal cord glioma. A 20-year-old girl presented with neck pain and new significant neurological deficits 17 years after resection of a posterior fossa medullomyoblastoma and subsequent craniospinal irradiation. She was found to have a cervical intramedullary tumor that was resected using a standard microsurgical technique. The permanent histopathological diagnosis was anaplastic astrocytoma. Her neurological status was worse immediately following the operation. She improved to her pre-operative status, but then had a relentless neurological decline resulting in death 16 weeks following surgery. Because of the high incidence of malignancy in the few radiation-induced spinal cord gliomas reported in the literature, and the poor outcome independent of therapy in patients with malignant spinal cord gliomas, an initial strategy of biopsy only may be more appropriate than attempted resection for the patient with a suspected radiation-induced intramedullary spinal cord tumor.

Impact of radiation technique upon the outcome of treatment for medulloblastoma

Craniospinal irradiation (CSI) is an essential component of the therapy of medulloblastoma. Because medulloblastoma disseminates via the cerebrospinal fluid (CSF), CSI technique involves the irradiation of all CSF-bearing areas which are at risk for tumor seeding. Underdosing with radiation because of inadequacies in CSI technique will produce dose "cold spots" which have the potential of serving as a nidus for tumor recurrence. A simple mathematic model of subclinical disease in medulloblastoma based on the available data concerning the radiosensitivity of medulloblastoma cell lines as well as the known clinical dose-response relationships support the hypothesis that for most cases of medulloblastoma, the radiotherapist is working in a range of doses arrayed on the steep portion of the tumor control probability curve. Underdosing of CSF-bearing areas because of technical problems at the junction of the cranial and spinal fields of irradiation, placement of shielding blocks in the cribiform plate-subfrontal region, and/or anatomic errors in the design of the caudal end of the CSI fields may lead to significant risks of tumor relapse. One may debate the necessity of a posterior fossa boost encompassing the entire anatomic posterior fossa rather than the primary tumor volume with a margin. This review critically evaluates the potential impact of CSI technique upon the outcome of treatment for medulloblastoma, and suggests future areas of inquiry.

Results of a prospective randomized trial comparing standard dose neuraxis irradiation (3,600 cGy/20) with reduced neuraxis irradiation (2,340 cGy/13) in patients with low-stage medulloblastoma. A Combined Children's Cancer Group-Pediatric Oncology Group Study

PURPOSE

To determine in a prospective randomized trial the effect on survival, progression-free survival, and patterns of relapse of a decrease in the neuraxis radiation dose from 3,600 cGy in 20 fractions to 2,340 cGy in 13 fractions in patients with newly diagnosed medulloblastoma between 3 and 21 years of age with low T stage (T1, T2 and T3A), minimal postoperative residual tumor, and no evidence of dissemination (M0).

METHODS AND MATERIALS

Between June 1986 and November 1990, the Children's Cancer Group and the Pediatric Oncology Group randomized 126 patients in a two-arm study comparing the two different doses of neuraxis irradiation. In both arms, the posterior fossa received 5,400 cGy in 30 fractions. All patients were staged with myelography, postoperative lumbar cerebrospinal fluid cytology, and postoperative contrast-enhanced cranial computerized tomography to ensure no evidence of dissemination and no more than 1.5 cm3 residual tumor volume. Overall survival, progression-free survival, and patterns of recurrence were carefully monitored. Prospective endocrine and psychometric studies were performed to determine the benefit of decreasing the neuraxis radiation dose.

RESULTS

Following an interim analysis at a median time on study of 16 months, the study was closed, since a statistically significant increase was observed in the number of all relapses as well as isolated neuraxis relapses in patients randomized to the lower dose of neuraxis radiation.

CONCLUSIONS

In patients with newly diagnosed medulloblastoma considered to have a good prognosis on the basis of low T stage, minimal residual tumor after at least subtotal resection, and no evidence of dissemination after thorough evaluation, there is an increased risk of early relapse associated with lowering the dose of neuraxis radiation from 3,600 cGy in 20 fractions to 2,340 cGy in 13 fractions.

Intellectual outcome in children with malignant tumors of the posterior fossa: influence of the field of irradiation and quality of surgery

The purpose of this study was to determine the respective parts played by cerebral hemisphere irradiation, posterior fossa irradiation, and surgery in the poor late functional results often observed in children treated for medulloblastoma. To do this we compared the intellectual outcome in a series of 59 children operated on for medulloblastoma, who had received whole-brain irradiation, to that observed in a series of 37 children operated on for ependymoma of the posterior fossa, who had received radiotherapy only on the posterior fossa. Only patients who had survived for more than 2 years without recurrence were included. At the assessment 1 year after treatment, intellectual outcome was somewhat better in the ependymoma group, but the difference was not statistically significant. At the long-term follow-ups at 5 and 10 years the results remained stable in the children treated for ependymoma, around 60% having an IQ above 90, whereas the intellectual level of the children treated for medulloblastoma was seen to have deteriorated progressively: 20% had an IQ above 90 5 years after treatment and only 10% at the 10-year follow-up. This progressive degradation is most likely due to the irradiation of the cerebral hemispheres, as this prophylactic irradiation constituted the only difference between the two groups. Moreover, irradiation to the posterior fossa did not seem to affect intellectual functions, since in the group of children with ependymomas the proportion of IQs above 90 was high and remained stable over the years. Surgery was certainly responsible for some poor results. The percentage of IQs above 90 observed 1-2 years after treatment was between 70 and 80 when no postoperative complications occurred, and only between 20-40% in the presence of postoperative complications. Postoperative aggravation was in most cases related to a brain-stem lesion. These results encourage the reduction, when possible, of irradiation to the cerebral hemispheres and underline the importance of the quality of surgery.

Cerebellar medulloblastoma in adults: report of 15 cases and review of the literature

From 1974 to 1988, 15 adult patients (aged over 16 years) with cerebellar medulloblastomas were observed in our Neurosurgical Department. All were treated by total (8 patients) or subtotal (7 patients) resection of the tumor, followed by radiation therapy to the posterior cranial fossa, spine and whole brain. A 5-year survival was achieved in 7 patients (46.6%). Local tumor recurrence occurred in 4 patients. The best treatment and the factors that influence the prognosis and survival of adult medulloblastomas are discussed also from the analysis of the pertinent literature.

Lymph node metastasis in medulloblastoma

A 14-year-old boy was diagnosed as having a medulloblastoma in the posterior fossa. Radiation therapy was given and the patient made a good recovery. Three months later he presented with supraclavicular lymph node metastasis, in the absence of other foci of metastases. He was treated with 60Co and the metastasis decreased. Two months later a bone scan and bone marrow aspiration showed bone metastasis. He was started on chemotherapy. The different possible mechanisms of metastasis are discussed.

Gantry angulation in brain CT: dosage implications, effect on posterior fossa artifacts, and current international practice

The aim of this study was first to determine the effect of use of different scan planes at computed tomography (CT) of the brain on lens radiation dose and on severity of posterior fossa artifact. Twenty patients requiring nonenhanced and contrast material-enhanced brain CT scanning were selected. Each was scanned with two different beam angulations, one passing through the eyes and one avoiding them, and the resulting radiation doses were measured. Angling of the beam to avoid the orbit reduced the dose by 87%, while the severity of posterior fossa artifacts was not significantly different. Second, the implications of these results was assessed by means of an international questionnaire survey of current scanning technique. Only 32% of the respondents routinely avoided the eye during brain CT. No single scan plane was accepted by the respondents as being superior in terms of minimizing posterior fossa artifact. The authors conclude that the potential exists for a reduction in lens dose after reappraisal of radiologic practice in brain CT.

Radiotherapy of glioblastoma multiforme

✓ A comparison is made between limited field and whole brain irradiation in the treatment of 60 patients with intracranial glioblastomas, 34 of whom were picked at random for either treatment and 26 who were selected for specific treatment. A significant increase in overall survival time and tumor-free period was found in the limited field treatment groups and this was especially significant in those patients selected for limited field treatment. The improved results are felt to be due to the higher dose permissible because of avoidance of more sensitive brain-stem structures. Tumor location in the frontal lobe also appears significant in the longer survival of those patients selected for limited field treatment. More exact localization of the lesion by brain scan, surgery, and angiography also contribute to more efficient treatment and consequently better survival.