Treatment of supratentorial high grade gliomas with split course high fractional dose postoperative radiotherapy

Clinical Results of Unconventional Fractionation Radiotherapy in Central Nervous System Tumors

Malignant brain tumors (primary and metastatic) are apparently resistant to most therapeutic efforts. Several randomized trials have provided evidence supporting the efficacy of radiation therapy. Attempts at improving the results of external beam radiotherapy include altered fractionation, radiation sensitizers and concomitant chemotherapy. In low-grade gliomas, all clinical studies with radiotherapy have employed conventional dose fractionation regimens. In high-grade gliomas, hypofractionation schedules represent effective palliative regimens in poor prognosis subsets of patients; short-term survival in these patients has not allowed to evaluate late toxicity. In tumors arising within the central nervous system, hyperfractionated irradiation exploits the differences in repair capacity between tumour and late responding normal tissues. It may allow for higher total dose and may result in increased tumor cell kill. Accelerated radiotherapy may reduce the repopulation of tumor cells between fractions. It may potentially improve tumor control for a given dose level, provided that there is no increase in late normal tissue injury. In supratentorial malignant gliomas, superiority of accelerated hyperfractionated over conventionally fractionated schedules was observed in a randomized trial; however, the gain in survival was less than 6 months. At present no other randomized trial supports the preferential choice for altered fractionation irradiation. Also in pediatric brainstem tumors there are no data to confirm the routine use of hyperfractionated irradiation, and significant late sequelae have been reported in the few long-term survivors. Shorter treatment courses with accelerated hyperfractionated radiotherapy may represent a useful alternative to conventional irradiation for the palliation of brain metastases. Different considerations have been proposed to explain this gap between theory and clinical data. Patients included in dose/effect studies are not stratified by prognostic factors and other treatment-related parameters. This observation precludes any definite conclusion about the relative role of conventional and of altered fractionation. New approaches are currently in progress. More prolonged radiation treatments, up to higher total doses, could delay time to tumor progression and improve survival in good prognosis subsets of patients; altered fractionation may be an effective therapeutic tool to achieve this goal.

Irradiation Fields and Doses in Glioblastoma Multiforme: Are Current Standards Adequate?

Aims and background

The optimum conventional radiotherapy in glioblastoma multiforme patients has not been clearly defined by prospective trials. To better characterize a standard radiotherapy in glioblastoma multiforme, the impact on survival of different fields and doses was analyzed in a retrospective single center series.

Methods

One hundred and forty-seven patients with glioblastoma multiforme, submitted to biopsy only (n = 15), subtotal (n = 48) or total resection (n = 82) and who completed the planned postsurgical radiotherapy, were considered. The median age was 57 years, the male/female ratio 1.5/1, and the performance status ≥70 in 76%. Whole brain irradiation, followed by a boost to partial brain, was used in 75 cases with a whole brain dose of 44–50 Gy (median, 46) and a partial brain dose of 56–70 Gy (median, 60 Gy). Partial brain irradiation alone was used in 72 patients with a dose of 56–70 Gy (median, 61 Gy). Ninety-eight patients received 56–60 Gy (median, 59 Gy) to partial brain whereas 49 patients received 61–70 Gy (median, 63 Gy).

Results

There was an almost significantly longer survival in patients irradiated to the partial brain alone with respect to those also receiving whole brain radiotherapy (P = 0.056). Doses <60 Gy significantly prolonged survival (P = 0.006). Multivariate analysis confirmed that the impact on survival of radiation dose was independent of age, performance status, extent of surgery, field of irradiation and the use of chemotherapy. The extent of irradiation field was not independently related to improved survival.

Conclusions

Our retrospective findings suggest that we reflect on the adequacy of the current standard irradiation parameters. Well-designed prospective trials are necessary to standardize the radiotherapy control group in patients with glioblastoma multiforme to be compared in phase III trials with innovative therapeutic approaches.

Modified optimal fractionation for poor prognosis malignant gliomas: an elusive search

The prognosis of malignant gliomas has not changed much over the last few decades despite refinements in neurosurgical techniques, high-precision radiotherapy, and newer chemotherapeutic agents. The median survival of poor prognosis malignant gliomas (older and/or poor performance status patients) still remains in the range of 6-9 months following maximal safe resection and postoperative conventionally fractionated adjuvant radiotherapy with or without chemotherapy. However, six weeks of daily radiotherapy does seem inappropriate in relation to the short expected survival time in this subset and there is an increasing emphasis on reducing the overall treatment time and the number of hospital visits by such patients. This can be achieved either by accelerated radiotherapy or by hypofractionated radiation, both of which are equivalent to conventional fractionation in terms of palliative effect and survival, as in discussed in this review. Despite enough evidence, such alteration of fractionation has not gained widespread acceptance by the oncologic fraternity. This review has been conducted to collate the evidence that could help shift the paradigm from conventional to modified fractionation in poor prognosis malignant glioma patients.

Protracted exposure radiosensitization of experimental human malignant glioma

Clinical modulation of radiosensitivity via combined fractionated high dose rate and continuous ultra-low dose rate irradiation (ULDR) holds promise for the radiosensitization of human malignant gliomas. We measured both the in vitro and in vivo responses of a human malignant glioma cell line to combined continuous ULDR and high dose rate treatments. For in vitro ULDR treatments, U251 human malignant glioma cells were cultured in media containing tritiated water to yield a continuous dose rate of 0.03 Gy/hr. After exposures of 24, 48, or 72 hr, cells were acutely (1.1 Gy/min) irradiated, replated, and scored for colony formation. In vivo, U251 flank xenografts in nude mice had 125-iodine (125-I) seed brachytherapy at a dose rate of 0.05 Gy/hr. For whole-body continuous ULDR (0.03 Gy/hr), a 137-Cs source was mounted a fixed distance above the cages of animals bearing xenografts. After 3 days' continuous exposure, xenografts were acutely irradiated (2 Gy x 8 vs. 5 Gy x 2 daily fractions), and the regrowth delay in tumors was measured. In vitro, exposure to ULDR (0.03 Gy/hr) alone caused only modest killing and reduced the surviving fraction by approximately 0.2 logs after 72 hr exposure. The highest (10 Gy) dose of acute irradiation alone reduced survival by 1 log. However, U251 cell killing increased to 2.5 logs after combined HDR and ULDR treatments. Linear-quadratic modeling showed comparatively greater increase in the beta than the alpha coefficients of the linear-quadratic model for cell killing. In vivo, the 125-I seed brachytherapy treatments delayed tumor growth but resulted in no regression. The HDR treatments (5 Gy x 2 or 2 Gy x 8 daily fractions) caused growth delays (in days) of 17+/-2 or 16+/-2 (P=NS) days, respectively. The combined seed and 5 Gy x 2 or 2 Gy x 8 daily fractions regimen resulted in striking prolongation of regrowth delay (52.3+/-8.7 vs. 59.5+/-7.7 days) (P < 0.001 vs. HDR treatments alone). External ULDR alone caused no regression and minimal growth delay. Combined continuous external ULDR and the 5 Gy x 2 vs. 2 Gy x 8 daily fraction regimens resulted in prolongation of growth delay (33+/-0.9 (P=0.01 vs. 5 Gy x 2 daily fractions alone) vs. 35+/-0.7 (P=0.049 vs. 2 Gy x 8 daily fractions alone). We conclude that continuous ULDR increases the effect of HDR treatments of experimental malignant glioma. This increased effect may prove clinically important in the treatment of human malignant brain tumors.

Dynamic determination of human glioma invasion in vitro

OBJECT

The goal of this study was to evaluate whether there is any relationship between survival of patients with brain tumor and tumor proliferation or tumor invasion in vitro.

METHODS

Samples of freshly resected brain tumors from 14 patients with glioblastoma multiforme (GBM) were directly grown as three-dimensional multicellular spheroids. The tumor spheroids were cocultured with fetal rat brain cell aggregates (BCAs), used to represent an organotypical normal brain tissue model. Before the coculture, the tumor spheroids and the BCAs were stained with two different carbocyanine dyes, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) and 3,3'-dioctadecycloxacarbocyanine perchlorate (DiO), respectively. During the coculture, confocal laser scanning microscopy allowed a sequential analysis of tumor cell invasion by visualizing dynamic aspects of the invasive process. Single cocultures were examined at three different time points (24, 48, and 96 hours). During the observation period there was a change in the structural morphology of the cocultures, with a progressive decrease in BCA volume. Furthermore, the scanning confocal micrographs revealed a bidirectional movement of tumor cells and normal cells into brain and tumor tissue, respectively. It is also shown that there is a considerable variation in the rate of BCA destruction in cocultures of glioma spheroids generated directly from biopsy specimens. This variation is seen both between spheroids generated from the same biopsy as well as between spheroids that are grown from different biopsy specimens. Cell proliferation measured by Ki-67 immunohistochemical analysis of biopsy samples obtained in the same patients revealed a correlation between tumor cell proliferation and tissue destruction of the BCAs, as determined by a reduction in BCA volume (p = 0.0338). No correlation was found when survival was related to the same parameters (p > 0.05).

CONCLUSIONS

The present work provides a model for quick and efficient assessment of dynamic interactions between tumor and normal brain tissue shortly after surgery.

Altered therapy schedules in postoperative treatment of patients with malignant gliomas. Twenty year experience of the Maria Skłodowska-Curie Memorial Center in Kraków, 1973-1993

Results of altered therapy schedules obtained in postoperative treatment of 294 patients with malignant gliomas over last 20 years are presented. During this period 135 patients received Conventional Irradiation and Chemotherapy (CICH), 61 patients received Conventional Irradiation (CI), 59 patients received Split Course High Fractional Dose Irradiation (SCHFDI), and 39 patients received Twice a Day Accelerated Irradiation (TDAI). Actuarial survival rates at 2, 3 and 5 years were 19%, 7%, 0% respectively for patients treated with CICH, and they were 21%, 10%, 0% for CI group, 24%, 12%, 0% for SCHFDI option and 15%, 8%, 0% for TDAI schedule. According to the Cox proportional hazard model, only age was significant factor in prognosis.

Short course radiotherapy is an appropriate option for most malignant glioma patients

PURPOSE

To determine whether a shortened course of radiotherapy (RT) is an appropriate treatment option for malignant glioma patients.

METHODS AND MATERIALS

Prognostic groups published by the Radiation Therapy Oncology Group (RTOG) are used to compare results for a short radiotherapy regimen with results of aggressive protocol treatment. The study group includes 219 patients treated during 1975-1993 with 51 Gy in 17 fractions. Patients were retrospectively assigned to six prognostic groups previously identified in a recursive partitioning analysis of the RTOG. The prognostic groups are based on age, histology, performance status, mental status, neurologic function, resection extent, length of symptoms, and RT dose.

RESULTS

The six RTOG prognostic groupings were significantly predictive of outcome for patients treated with this shortened regimen (log-rank, p < 0.001). The median survival for our patients by RTOG groups 1-6 were 68, 57, 22, 13, 8, and 5 months, respectively. Two-year survival results were 64, 67, 45, 8, 3, and 3%. The median and two-year survival results for each prognostic grouping were similar to the results achieved by aggressive treatment on RTOG malignant glioma trials for selected patients. Treatment toxicity was uncommon.

CONCLUSION

This shortened regimen is an appropriate treatment option for most malignant glioma patients (RTOG groups 4-6), resulting in similar survival as standard regimens with reduced patient effort and cost. Although acute side effects are acceptable and the risk of brain necrosis is low, we do not recommend this treatment to the minority of patients who have a substantial long term survival probability (RTOG groups 1-3) because long term neurocognitive assessment is lacking.

Multivariate analysis of prognostic factors in 106 patients with malignant glioma

The aim of this study was to evaluate the outcome and prognostic factors influencing survival in 106 patients with supratentorial malignant gliomas treated with radiotherapy. The study group included 84 patients treated by surgery and post-operative radiotherapy and 22 patients treated by postbiopsy irradiation. Radiotherapy was delivered to the tumour area with a 2 cm margin, the aimed curative dose was 60 Gy in 6-7 weeks. The 60-month overall survival (Kaplan-Meier) was 20%. Following a univariate analysis, younger age (P < 0.001), longer duration of symptoms (P = 0.009), good performance status after radiotherapy (P < 0.001), other than grade 4 histology (P < 0.001) and higher radiation dose (P < 0.001) were associated with better overall survival rates. Multivariate analysis found that age, symptom duration, histology, extent of symptoms and radiation dose were independent prognostic factors influencing survival. In conclusion, conventional radiotherapy of supratentorial malignant gliomas results in survival that is comparable to results from clinical experiments with different fractionation schedules and radiation with chemotherapy or radiosensitisers. To improve the results, new approaches are needed, especially for patients with the poorest prognosis after standard treatment.

Accelerated hyperfractionated radiotherapy for malignant gliomas

PURPOSE

To evaluate accelerated hyperfractionated radiotherapy for the treatment of malignant gliomas.

METHODS AND MATERIALS

Between April 1985 and June 1994, 70 adult patients with pathologically confirmed malignant glioma (75% glioblastoma multiforme, 25% anaplastic astrocytoma) suitable for high-dose therapy were selected for treatment with accelerated hyperfractionated radiotherapy, 1.5 Gy twice daily to a total target dose of 60 Gy. Two patients were excluded from analysis (one patient had a fatal pulmonary embolism after 18 Gy; one patient discontinued therapy after 28.5 Gy against medical advice and without sequelae or progression). The 68 patients in the study group had a median age of 52 years and a median Karnofsky performance status of 90. Stereotactic implant (125I) or stereotactic radiosurgery boosts were delivered to 16 patients (24%) in the study group. Minimum follow-up was 6 months.

RESULTS

Median survival was 13.8 months and median progression-free survival was 7.4 months. The absolute Kaplan-Meier survival rate was 16% at 2 years and 4% at 5 years. Multivariate analysis for the prognostic impact of age, gender, histology, Karnofsky performance status, symptomatology, surgical resection vs. biopsy, and boost vs. nonboost therapy revealed that Karnofsky performance status > or = 90, boost therapy, and surgical excision predicted significantly improved outcome. No severe toxicity occurred in patients treated with accelerated hyperfractionated radiotherapy alone, although 5% required steroids temporarily for edema. Progression occurred during treatment in one patient (1.5%).

CONCLUSION

This regimen of accelerated hyperfractionated radiotherapy is well tolerated and leads to results comparable with those of standard therapy. The rate of disease progression during treatment is significantly better (p = 0.001) than is reported for patients treated with standard fractionation, with or without chemotherapy. This regimen is a reasonable starting point for future trials and may have some advantages over standard fractionation.

Hypofractionated radiation therapy in patients with glioblastoma multiforme: results of treatment and impact of prognostic factors

PURPOSE

Median survival of patients with glioblastoma multiforme (GBM) is only about 4 months with surgery and about 9 months for surgery followed by radiotherapy. Prolonged treatment is futile for many patients and the time of treatment and hospitalization should be minimized.

METHODS AND MATERIALS

This was a prospective, nonrandomized study of 30 patients treated with a hypofractionated radiation scheme (42 Gy in 14 fractions).

RESULTS

Median survival was 36 weeks. Age, Karnofsky performance status (KPS) and extent of surgery were strongly interrelated and all correlated with survival (p < 0.05). Three prognostic groups were identified. Patients with three favorable prognostic factors (age <50, KPS 80-100, and > or = 75% of the tumor removed) had the best prognosis (median survival 50 weeks). Patients with no favorable prognostic factors (age > or = 50, KPS < or = 70, and < 75% of the tumor removed) had the worst prognosis (median survival 25 weeks). Median survival of the intermediate group (with one or two favorable prognostic factors) was 38 weeks. No severe acute or late toxicity was observed.

CONCLUSION

The treatment results are comparable to those achieved with conventional radiotherapy schemes. Based on the number of favorable prognostic factors (age < 50, KPS 80-100 and > or = 75% of tumor resected) the radiation schedule should be selected.

Oropharyngeal cancer in the elderly

PURPOSE

The poor prognosis of elderly patients in many cancers may be due to less thorough investigation and less aggressive treatment because of the perception that radical treatment will be poorly tolerated and that elderly patients have a limited life expectancy. We wished to assess whether older age is associated with (a) less radical treatment, (b) poorer outcome, or (c) greater toxicity, after adjusting for other possible contributing factors.

METHODS AND MATERIALS

A retrospective study of patients with loco-regional oropharyngeal cancer treated between January 1980 and December 1985 was conducted. Patients were treated with radiotherapy, surgery, chemotherapy, or combinations. Cox regression was used to assess age effects while allowing for the influence of other factors.

RESULTS

Eighty-eight patients were treated radically and 16 palliatively. Treatment intent (radical or palliative) did not appear to be related to age, before (p = 0.42) or after adjusting for other factors (p = 0.34). In a selected group of 86 radically treated patients ages ranged from 33 to 85 (median 60). There were 35 loco-regional failures and 58 deaths (38 related to oropharyngeal cancer). Older patients were prescribed and received lower doses of radiation. However, older age was not related to the risk of loco-regional recurrence (p = 0.96) or shorter survival (p = 0.67), and was not associated with duration of treatment interruption or severity of toxicity after adjustment for prognostic factors. There was some suggestion of a higher risk of recurrence with increasing age for patients under 70 years but with a risk for patients over 70 at least equal to that of the youngest group. Elderly patients in our study may have been a selected group.

CONCLUSION

Older patients with loco-regional oropharyngeal cancer, or at least a subset of them, appear to be able to tolerate radical courses of radiotherapy, and to have similar outcomes as do younger patients.

Linac radiosurgery for high-grade gliomas: the University of Florida experience

PURPOSE

Stereotactic radiosurgery has been reported as a promising boost technique for the treatment of selected patients with high-grade glioma. The first 11 patients given this treatment at the University of Florida are reported.

METHODS AND MATERIALS

Six patients with glioblastoma multiforme and five with anaplastic astrocytoma were carefully selected for treatment with linac radiosurgery. All patients had a Karnofsky performance status > or = 90%. Median age of patients was 42.1 years. External-beam radiotherapy delivered a median dose of 60 Gy. Stereotactic radiosurgery was delivered to the enhancing tumor volume without margin. Median treatment volume was 14 cm3 (equivalent sphere diameter, 3 cm). The maximum volume of any tumor treated was 22.5 cm3 (equivalent sphere diameter, 3.5 cm). Median stereotactic radiosurgery boost dose was 12.5 Gy, and median prescription sphere was the 80% isodose shell.

RESULTS

Despite rigorous selection and aggressive stereotactic boost irradiation, this patient cohort had a median actuarial survival of 17 months. All patients have had progression of intracranial disease within 1 year of radiosurgery, and only 3 of 11 remain alive with a median follow-up of 13 months.

CONCLUSION

These results differ significantly from others reported. Comparative analysis suggests tumor volume may be an important prognostic factor in patients treated with stereotactic radiosurgery. Future studies need to define appropriate patient cohorts for the boost technique.

Hypofractionated radiotherapy as palliative treatment in poor prognosis patients with high grade glioma

We report the palliative effectiveness of a hypofractionated radiotherapy regimen in patients with poor prognosis high grade glioma. Thirty-eight elderly, and/or disabled patients received radiotherapy to a dose of 30 Gy in 6 fractions over 2 weeks to a planning target volume defined by the enhancing tumour and a 2-cm margin. The median survival was 6 months with a 1-year survival rate of 23%. Treatment was without acute toxicity. One month after radiotherapy, functional status, assessed using a verbally administered Barthel index, improved in 38% and remained stable in a further 39% of surviving patients. At 3 months 39% of surviving patients had improved and a further 12% remained stable. We conclude that in the poor prognostic group of patients with high grade glioma hypofractionated partial brain radiotherapy is well tolerated, convenient and provides effective palliation in a proportion of patients. Comparison with conventional radiotherapy or symptomatic care alone require further evaluation in randomised studies.

Postoperative hypofractionated radiotherapy versus conventionally fractionated radiotherapy in malignant gliomas. A preliminary report on a randomized trial

A prospective randomized study of 108 patients with cerebral malignant gliomas was carried out at the Department of Radiation Oncology of Maria Sklodowska-Curie Memorial Center in Kraków. 44 patients with histologically proven glioblastoma multiforme and 64 patients with anaplastic astrocytoma received postoperative radiotherapy. Patients were randomized to two treatment arms: Conventionally Fractionated Radiotherapy (CFR) and Hypofractionated Radiotherapy (HF). In the CFR group, the whole brain was irradiated to the total dose of 50 Gy in 25 fractions over 5 weeks, then a 10 Gy 'boost' in 5 fractions in 5 days was delivered to the site of the primary lesion. In the HF group, there were 3 courses of irradiation separated by a one month interval. In each of the two first series the patients received 20 Gy in 5 fractions in 5 days to the whole brain, and in the third course, 10 Gy 'boost' in 5 days was delivered as in the CFR regimen. The tolerance to treatment has been found to be good in both groups. The 2-year actuarial survival rate for patients with anaplastic astrocytoma was 22% for CFR and 18% for HF. Patients with glioblastoma multiforme treated with HF had a better prognosis in comparison to the CFR group with the two-year actuarial survival rates being 23% and 10%, respectively. This difference is statistically significant at the 0.05 level.

Radiation in the treatment of high grade malignant gliomas in Queensland

Two hundred and seventy eight patients with histologically proven grade 3 or grade 4 astrocytomas were referred to the Queensland Radium Institute for consideration of radiotherapy between January 1980 and December 1987. The role of radiation in the management of these tumours was examined with respect to the effects of field size, dose and age. It was found that field size did not have a significant effect on survival; in particular whole brain irradiation for patients with grade 4 tumours was not a significant advantage. The doses used at the Queensland Radium Institute produce similar survivals to those used in other centres. The effect of age was significant. For grade 3 tumours there was a survival advantage to those under 50 years receiving radiation, but not to those above that age. For grade 4 tumours, the survival advantage was for those under 60 years, but those over 60 years did seem to get some benefit although the difference did not reach significance. It is suggested that, as the tumour is generally incurable, these patients may be better served by a short simple palliative course of radiation.

Accelerated fractionation for high-grade cerebral astrocytomas. Preliminary treatment results

A Phase I/II accelerated fractionation study for high-grade cerebral astrocytomas began in October 1987. Forty-two patients, 25 men and 17 women, were entered in the study. Median age was 58.5 years of age (range, 32 to 78 years). Performance status was 0, 1, 2, and 3 on Eastern Cooperative Oncology Group (ECOG) scale for 13, 19, 9, and 1 patients, respectively. Thirty-six patients had undergone partial resection, and six had stereotactic biopsy only. All patients had histologically proven astrocytomas (6 Grade 3, and 36 Grade 4). Treatment consisted of radiation therapy doses of 4400 cGy in 22 daily fractions to the whole brain plus a boost of 1600 cGy in 8 fractions given concomitantly with the last 8 whole-brain treatments using a twice daily schedule with an interfraction interval of 8 hours. Median survival time was 57 weeks from the date of starting irradiation. Survival was 50% and 28% at 1 and 2 years, respectively. Alopecia and scalp erythema were seen in all patients; nine patients had localized areas of moist desquamation in the retroauricular region. Decreased hearing and serous otitis media were seen in five patients within 1 to 2 months from the end of treatment. Increasing somnolence was marked in eight patients with progressive deterioration of performance status; computerized axial tomography (CAT) scan studies in all eight patients showed evidence of disease recurrence with associated brain edema and mass effect. Three patients had a second resection for a recurrent tumor with no evidence of brain necrosis at craniotomy. To date, the accelerated fractionation schedule appears to be well tolerated with valuable shortening of overall treatment time. The preliminary results are encouraging, and longer follow-up time is required to evaluate tumor control and toxicity.

Interstitial thermoradiotherapy of brain tumors: preliminary results of a phase I clinical trial

A Phase I clinical trial has been initiated to determine the feasibility, tolerance, and toxicity of interstitial thermoradiotherapy in the treatment of high-grade supratentorial brain gliomas. Hyperthermia was delivered by means of thermally-regulating ferromagnetic implants afterloaded into stereotactically placed plastic catheters. Heat treatments were given immediately before interstitial irradiation; in addition, five patients received a second heat treatment at the completion of brachytherapy. The desired target temperature for the 60-minute hyperthermia session was between 42 degrees C and 45 degrees C. Following hyperthermia, the catheters were afterloaded with Ir-192, which delivered a variable radiation dose of 14-50 Gy depending on the clinical situation. Interstitial irradiation was supplemented with external beam radiotherapy (40-41.4 Gy) in patients with previously untreated tumors. A total of 14 patients (4 males, 10 females) have been treated to date on this protocol. Eleven of the patients had a diagnosis of glioblastoma multiforme, whereas three had anaplastic astrocytoma. The mean implant volume was 61.5 cm3 (range: 9-119 cm3); the median number of interstitial treatment catheters implanted was 19 (range: 7-33). Continuous temperature monitoring was performed by means of multisensor thermocouple probes inserted in the center as well as in the periphery of the tumor. Of the 175 monitored intratumoral points, 83 (47%) had time-averaged mean temperatures of greater than 42 degrees C, and only 12 sensors (7%) exceeded a temperature of 45 degrees C. Among the 19 heat treatments attempted, there have been four minor acute toxicities, all of which resolved with conservative medical management and one major complication resulting in the demise of a patient. These preliminary results indicate that ferromagnetic implants offer a promising new approach to treating brain tumors with hyperthermia.