Adjuvant Chemoradiotherapy within One Year of Resection for Molecularly Defined Astrocytoma

PURPOSE/OBJECTIVE(S)

Treatments for diffuse low-grade gliomas (LGG) are controversial. Level I evidence supports the use of adjuvant radiotherapy (RT) and PCV chemotherapy for histologic LGG, but integration of molecular biomarkers in recent WHO classification and the emergence of temozolomide chemotherapy for gliomas necessitates additional investigation of the optimal treatment and timing of postoperative interventions. We hypothesized molecularly-defined LGG (IDH-mutant astrocytoma (astro) and IDH-mutant, 1p/19q-codeleted oligodendroglioma (oligo)) may have different clinical outcomes following adjuvant RT (aRT) with chemotherapy (aRT+chemo) vs observation or chemo alone.

MATERIALS/METHODS

A retrospective analysis of consecutive adult patients diagnosed with WHO Grade 2 astrocytoma or oligodendroglioma who underwent initial resection at a single institution from January 1998 to November 2017 was performed. Wilcoxon rank sum and Chi-squared tests were used to compare continuous and categorical variables, respectively. Survival analyses were performed using the Kaplan-Meier method and Cox proportional hazards models. Patients without clinical progression or death were censored at the date of last follow-up. Pre-operative and post-operative T2 FLAIR hyperintense tumor volumes were quantified using 3D Slicer to calculate extent of resection (EOR).

RESULTS

A total of 342 patients with molecularly-defined LGG (178 astro, 164 oligo) were identified with a median follow up of 9.1 yr. 171 (50%) patients received RT during their treatment course, of which 31 (18%) were treated with aRT within 1 year of diagnosis. The median aRT dose was 54 Gy (range: 40-60 Gy). aRT was more likely for astro (58%) vs oligo (41%, p = 0.001) and for patients who had resections with lower median EOR (88% vs 95%, p = 0.014). 53 patients (15%) were treated with chemo alone, and 136 patients (40%) were treated with aRT+chemo. Temozolomide was used for 161 patients (85%). For astro, aRT+chemo was associated with longer PFS (median 14.9 yr) compared to observation (4.8 yr, p = 0.05), aRT without chemo (5.2 yr, p = 0.01), or chemo alone (4.7 yr, p = 0.02). For oligo, aRT+chemo was associated with longer PFS (median not reached) compared to aRT without chemo (1.6 yr, p = 0.03), but not when compared to observation (median not reached, p = 0.47), or chemo alone (7.9 yr, p = 0.45). Multivariate analysis showed preoperative tumor volume, EOR, and aRT+chemo (but not aRT or chemo alone) were independently associated with astro PFS compared to observation. Propensity matching based on pre-operative tumor volume, EOR, and age demonstrated longer astro PFS after aRT+chemo (14.9 yr) compared to observation or chemo alone (4.5 yr, p = 0.015), without significant difference in OS (18.2 vs. 11.5 yr, p = 0.40).

CONCLUSION

Retrospective data from a single institution support the use of adjuvant radiotherapy with chemotherapy for patients with molecular astrocytomas, while the role of this approach for oligodendrogliomas is unclear in this cohort.

A Two-Step Optimization Method for Improving Multiple Brain Lesion Treatments with Robotic Radiosurgery

Planning robotic radiosurgery treatments for multiple (n > 3) metastatic brain lesions is challenging due to the need of satisfying a large number of dose-volume constraints and the requirement of prescribing different dose levels to individual targets. In this study, we developed a sequential two-step optimization technique to improve the planning quality of such treatments. In contrast to the conventional approach of where all targets are simultaneously planned, we have developed a two-step optimization method. In this method, the first step was to create treatment plans for individual targets. In the second step, the 3D dose matrices associated with each plan were exported to Dicom-RT digital files and subsequently optimized. For the optimization, a singular-value-decomposition (SVD) algorithm was implemented to minimize the dose interferences among different targets. Finally, we compared the optimized treatment plans with the treatment plans created using the conventional method to determine the effectiveness of the new method. Large improvements in target dose distributions as well as normal brain sparing were found for the two-step optimization treatment plans as compared with the conventional treatment plans. The two-step optimization significantly lowered the volume of normal brain receiving relatively low doses. For example, the normal brain volume receiving 12-Gy was reduced by averaged 42% (range 34%–47%) with the two-step optimization. Such improvements generally enlarged with increasing number of targets being treated regardless of target sizes. Of note, normal brain dose was found to increase non-linearly with increasing number of targets. In summary, a two-step optimization technique is demonstrated to significantly improve the treatment plan quality as well as reduce the planning effort for multi-target robotic radiosurgery.

Distinguishing recurrent intra-axial metastatic tumor from radiation necrosis following gamma knife radiosurgery using dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging

BACKGROUND AND PURPOSE

MR image-guided gamma knife radiosurgery is often used to treat intra-axial metastatic neoplasms. Following treatment, it is often difficult to determine whether a progressively enhancing lesion is due to metastatic tumor recurrence or radiation necrosis. The purpose of our study was to determine whether relative cerebral blood volume (rCBV), relative peak height (rPH), and percentage of signal-intensity recovery (PSR) derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging can distinguish recurrent metastatic tumor from radiation necrosis.

MATERIALS AND METHODS

Twenty-seven patients with systemic cancer underwent gamma knife radiosurgery for metastatic lesions of the brain and subsequently developed enlarging regions of enhancement within the radiation field. Subsequent surgical resection or clinicoradiologic follow-up established a diagnosis of recurrent metastatic tumor or radiation necrosis. Perfusion MR imaging datasets were retrospectively reprocessed, and regions of interest were drawn around the entire contrast-enhancing region. The resulting T2* signal-intensity time curves produced rCBV, rPH, and PSR values for each examination. A Welch t test was used to compare imaging values between groups.

RESULTS

The mean, minimum, and maximum PSR values were significantly lower (P < .01) in cases of recurrent metastatic tumor. The mean and maximum rCBV and rPH values were significantly higher (P < .02) in the recurrent metastatic tumor group.

CONCLUSIONS

The findings of our study suggest that perfusion MR imaging may be used to differentiate recurrent intra-axial metastatic tumor from gamma knife-induced radiation necrosis.

Stereotactic Radiosurgery and Interstitial Brachytherapy for Glial Neoplasms

The application of focal radiation therapies in the management of malignant gliomas has gone through a number of stages. Earlier efforts to improve local control of malignant gliomas involved the use of brachytherapy. Despite some early encouraging results, Phase 3 studies did not prove a significant survival benefit for the addition of brachytherapy for newly diagnosed glioblastoma. Most recently radiosurgery has been employed using the same rationale in that improved local control may improve survival. Results of the RTOG Phase 3 study are pending final publication, but early abstracted reports are negative. While radiosurgery and brachytherapy continue to be used as a form of therapy for selected patients with recurrent gliomas, new information from metabolic imaging studies suggests our problem with these techniques in part may be related to targeting. This paper reviews the recent literature and results of the use of brachytherapy and radiosurgery in the management of newly diagnosed and recurrent malignant gliomas.

Radiosurgery and radiotherapy for non-small-cell lung cancer metastatic to brain

Non-small-cell lung cancer metastatic to brain represents a common problem in oncology. Treatment modalities include stereotactic radiosurgery (SRS), whole-brain radiotherapy (WBRT), surgical resection, supportive care, or a combination of these options. This review outlines therapeutic strategies for treatment with particular attention to the use of SRS. Radiosurgical technique, radiobiology, dose prescription, patient selection, and results of therapy are discussed. The term SRS describes a radiation procedure that utilizes a three-dimensional stereotactic localization system to precisely treat small intracranial targets with a single, large, highly focal radiation dose. Stereotactic radiosurgery is appealing for several reasons; it is minimally invasive, easily tolerated, and highly effective, and patients return to normal baseline function within 24 hours. Stereotactic radiosurgery provides much higher control rates of treated lesions than does WBRT. Randomized trials are underway to ascertain the optimal role and timing of SRS in relation to WBRT in order to maximize control, survival, quality of life, and neuropsychological outcome.

Dose conformity of gamma knife radiosurgery and risk factors for complications

PURPOSE

To quantitatively evaluate dose conformity achieved using Gamma Knife radiosurgery, compare results with those reported in the literature, and evaluate risk factors for complications.

METHODS AND MATERIALS

All lesions treated at our institution with Gamma Knife radiosurgery from May 1993 (when volume criteria were routinely recorded) through December 1998 were reviewed. Lesions were excluded from analysis for reasons listed below. Conformity index (the ratio of prescription volume to target volume) was calculated for all evaluable lesions and for lesions comparable to those reported in the literature on conformity of linac radiosurgery. Univariate Cox regression models were used to test for associations between treatment parameters and toxicity.

RESULTS

Of 1612 targets treated in 874 patients, 274 were excluded, most commonly for unavailability of individual prescription volume data because two or more lesions were included within the same dose matrix (176 lesions), intentional partial coverage for staged treatment of large arteriovenous malformations (AVMs) (33 lesions), and missing target volume data (26 lesions). The median conformity indices were 1.67 for all 1338 evaluable lesions and 1.40-1.43 for lesions comparable to two linac radiosurgery series that reported conformity indices of 1.8 and 2.7, respectively. Among all 651 patients evaluable for complications, there were one Grade 5, eight Grade 4, and 27 Grade 3 complications. Increased risk of toxicity was associated with larger target volume, maximum lesion diameter, prescription volume, or volume of nontarget tissue within the prescription volume.

CONCLUSIONS

Gamma Knife radiosurgery achieves much more conformal dose distributions than those reported for conventional linac radiosurgery and somewhat more conformal dose distributions than sophisticated linac radiosurgery techniques. Larger target, nontarget, or prescription volumes are associated with increased risk of toxicity.

Age and radiation response in glioblastoma multiforme

OBJECTIVE

Advanced age is a strong predictor of shorter survival in patients with glioblastoma multiforme (GM), especially for those who receive multimodality treatment. Radiographically assessed tumor response to external beam radiation therapy is an important prognostic factor in GM. We hypothesized that older GM patients might have more radioresistant tumors.

METHODS

We studied radiographically assessed response to external beam radiation treatment (five-level scale) in relation to age and other prognostic factors in a cohort of 301 GM patients treated on two prospective clinical protocols. A total of 223 patients (74%) were assessable for radiographically assessed radiation response. A proportional odds ordinal regression model was used for univariate and multivariate analysis.

RESULTS

Younger age (P = 0.006), higher Karnofsky Performance Scale score before radiotherapy (P = 0.027), and more extensive surgical resection (P = 0.028) predicted better radiation response in univariate analyses. Results were similar when clinical criteria were used to classify an additional 61 patients without radiographically assessed radiation response (stable versus progressive disease). In multivariate analyses, age and extent of resection were significant independent predictors of radiation response (P < 0.05); Karnofsky Performance Scale score was of borderline significance (P = 0.07).

CONCLUSION

Older GM patients are less likely to have good responses to postoperative external beam radiation therapy. Karnofsky Performance Scale score before radiation treatment and extent of surgical resection are additional predictors of radiographically assessed radiation response in GM.

Radiosurgery for patients with brain metastases: a multi-institutional analysis, stratified by the RTOG recursive partitioning analysis method

PURPOSE

To estimate the potential improvement in survival for patients with brain metastases, stratified by the Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) class and treated with radiosurgery (RS) plus whole brain radiotherapy (WBRT).

METHODS AND MATERIALS

An analysis of the RS databases of 10 institutions identified patients with brain metastates treated with RS and WBRT. Patients were stratified into 1 of 3 RPA classes. Survival was evaluated using Kaplan-Meier estimates and proportional hazard regression analysis. A comparison of survival by class was carried out with the RTOG results in similar patients receiving WBRT alone.

RESULTS

Five hundred two patients were eligible (261 men and 241 women, median age 59 years, range 26-83). The overall median survival was 10.7 months. A higher Karnofsky performance status (p = 0.0001), a controlled primary (median survival = 11.6 vs. 8.8 months, p = 0.0023), absence of extracranial metastases (median survival 13.4 vs. 9.1 months, p = 0.0001), and lower RPA class (median survival 16.1 months for class I vs. 10.3 months for class II vs. 8.7 months for class III, p = 0.000007) predicted for improved survival. Gender, age, primary site, radiosurgery technique, and institution were not prognostic. The addition of RS boosted results in median survival (16.1, 10.3, and 8.7 months for classes I, II, and III, respectively) compared with the median survival (7.1, 4.2, and 2.3 months, p <0.05) observed in the RTOG RPA analysis for patients treated with WBRT alone.

CONCLUSION

In the absence of randomized data, these results suggest that RS may improve survival in patients with BM. The improvement in survival does not appear to be restricted by class for well-selected patients.

EGFR overexpression and radiation response in glioblastoma multiforme

PURPOSE

Recent studies have suggested relative radioresistance in glioblastoma multiforme (GM) tumors in older patients, consistent with their shorter survival. Two common molecular genetic abnormalities in GM are age related: epidermal growth factor receptor (EGFR) overexpression in older patients and p53 mutations in younger patients. We tested whether these abnormalities correlated with clinical heterogeneity in GM response to radiation treatment.

METHODS AND MATERIALS

Radiographically assessed radiation response (5-level scale) was correlated with EGFR immunoreactivity, p53 immunoreactivity, and p53 exon 5-8 mutation status in 170 GM patients treated using 2 prospective clinical protocols. Spearman rank correlation and proportional-odds ordinal regression were used for univariate and multivariate analysis.

RESULTS

Positive EGFR immunoreactivity predicted poor radiographically assessed radiation response (p = 0.046). Thirty-three percent of tumors with no EGFR immunoreactivity had good radiation responses (>50% reduction in tumor size by CT or MRI), compared to 18% of tumors with intermediate EGFR staining and 9% of tumors with strong staining. There was no significant relationship between p53 immunoreactivity or mutation status and radiation response. Significant relationships were noted between EGFR score and older age and between p53 score or mutation status and younger age.

CONCLUSION

The observed relative radioresistance of some GMs is associated with overexpression of EGFR.

MR-spectroscopy guided target delineation for high-grade gliomas

PURPOSE

Functional/metabolic information provided by MR-spectroscopy (MRSI) suggests MRI may not be a reliable indicator of active and microscopic disease in malignant brain tumors. We assessed the impact MRSI might have on the target volumes used for radiation therapy treatment planning for high-grade gliomas.

METHODS AND MATERIALS

Thirty-four patients (22 Grade III; 12 Grade IV astrocytomas) were evaluated; each had undergone MRI and MRSI studies before surgery. MRI data sets were contoured for T1 region of contrast enhancement (T1), region of necrosis, and T2 region of hyperintensity (T2). The three-dimensional MRSI peak parameters for choline (Cho) and N-acetylaspartate (NAA), acquired by a multivoxel technique, were categorized based on an abnormality index (AI), a quantitative assessment of tissue metabolite levels. The AI data were aligned to the MRI and displayed as three-dimensional contours. AI vs. T conjoint and disjoint volumes were compared.

RESULTS

For both grades, although T2 estimated the region at risk of microscopic disease as being as much as 50% greater than by MRSI, metabolically active tumor still extended outside the T2 region in 88% of patients by as many as 28 mm. In addition, T1 suggested a lesser volume and different location of active disease compared to MRSI.

CONCLUSION

The use of MRSI to define target volumes for RT treatment planning would increase, and change the location of, the volume receiving a boost dose as well as reduce the volume receiving a standard dose. Incorporation of MRSI into the treatment-planning process may have the potential to improve control while reducing complications.

Relationship between pattern of enhancement and local control of brain metastases after radiosurgery

PURPOSE

A desired goal in the radiosurgery (RS) of brain metastases is improved local control. Our earlier retrospective review identified pattern of enhancement on day-of-treatment imaging as a prognostic indicator for freedom from progression (FFP) after RS in 219 brain metastases. The current study was performed to corroborate this preliminary finding.

METHODS AND MATERIALS

Records and imaging studies of patients treated with RS from 1991 to 1997 were reviewed. Each metastasis was categorized as homogeneously-, heterogeneously-, or ring-enhancing. Kaplan-Meier FFP was calculated from the date of RS to the first imaging showing tumor progression. Univariate and multivariate analyses were performed using Cox proportional hazard models stratified by primary site and type of RS (alone, as a boost, or for recurrence).

RESULTS

Of 682 lesions in 258 patients, 518 lesions in 193 patients were evaluable. Pattern of enhancement was homogeneous in 59%, heterogeneous in 32%, and ring-like in 8% of lesions. One-year FFP probabilities for homogeneously-, heterogeneously-, and ring-enhancing lesions were 90% (95% confidence interval, 84-93%), 76% (64-84%), and 57% (35-74%), respectively. The p-value for pattern of enhancement from the stratified multivariate analysis was 0.019 adjusting for RS dose and treatment period (1991-1994 vs. 1995-1997). Similar results were achieved adjusting for tumor volume instead of RS dose.

CONCLUSION

Pattern of enhancement is confirmed as a significant prognostic factor for FFP of brain metastases treated with RS, independent of dose and volume. A possible explanation is radioresistance of hypoxic tumor cells associated with necrotic regions, suggesting future investigations with radiosensitizers, hypoxic cell sensitizers, or strategies to improve tumor oxygenation.

Radiosurgery for brain metastases from primary lung carcinoma

PURPOSE

Brain metastases are a common problem in patients with lung cancer. This retrospective review was performed to describe the efficacy and toxicity of stereotactic radiosurgery for brain metastases from lung carcinoma and to evaluate prognostic factors for survival.

PATIENTS AND METHODS

A retrospective review was performed of 113 patients with the diagnosis of lung carcinoma who underwent radiosurgery with or without whole-brain radiotherapy for management of newly diagnosed or recurrent, single, or multiple brain metastases from 1991 through 1998 at the University of California, San Francisco. Freedom from progression and survival were measured from the date of radiosurgery and estimated using the Kaplan-Meier method. Prognostic factors were evaluated with the log-rank test and Cox proportional hazards models.

RESULTS

The median patient age at the time of radiosurgery was 59 years (range, 37-82 years), and the median Karnofsky performance score was 90 (range, 50-100). The median survival time from radiosurgery was 12.0 months overall, 13.9 months for 41 patients treated with radiosurgery alone initially, 14.5 months for 19 patients treated with radiosurgery and whole-brain radiotherapy initially, and 10.0 months for 53 patients with recurrent brain metastases. Among newly diagnosed patients, multivariate analysis showed that improved survival was associated with absence of extracranial metastases and fewer brain metastases. Among patients with recurrent brain metastases, improved survival was associated with higher Karnofsky performance score, control of the primary tumor, and fewer metastases. Measured by lesion, 1-year local freedom from progression probabilities were 81% for radiosurgery alone, 86% for radiosurgery and whole-brain radiotherapy, and 65% for radiosurgery performed after recurrence. In patients with newly diagnosed brain metastases, there was a significantly greater risk of developing subsequent brain metastases and of worse overall brain freedom from progression after radiosurgery alone versus radiosurgery and whole-brain radiotherapy. One-year brain freedom from progression probabilities were 13% without salvage therapy and 62% with salvage therapy in the 41 patients treated initially with radiosurgery alone, versus 67% without salvage therapy and 89% with salvage therapy in the 19 patients treated initially with radiosurgery plus whole-brain radiotherapy.

DISCUSSION

Radiosurgery is an effective therapy for selected patients with newly diagnosed or recurrent brain metastases from lung carcinoma. Initial whole-brain radiotherapy with radiosurgery appears to improve brain control but not survival. Prospective, randomized trials are needed to further investigate the role of radiosurgery with and without whole-brain radiotherapy for brain metastases.

Phase III trial of accelerated hyperfractionation with or without difluromethylornithine (DFMO) versus standard fractionated radiotherapy with or without DFMO for newly diagnosed patients with glioblastoma multiforme

PURPOSE

To report the results of a prospective Phase III trial for patients with newly diagnosed glioblastoma multiforme (GBM), treated with either accelerated hyperfractionated irradiation with or without difluromethylornithine (DFMO) or standard fractionated irradiation with or without DFMO.

METHODS AND MATERIALS

Adult patients with newly diagnosed GBM were registered and randomized following surgery to one of 4 treatment arms: Arm A, accelerated hyperfractionation alone using 2 fractions a day of 1.6 Gy to a total dose of 70.4 Gy in 44 fractions; Arm B, accelerated hyperfractionation as above plus DFMO 1.8 gm/m2 by mouth every 8 h beginning one week before radiation until the last fraction was given; Arm C, single-fraction irradiation of 1.8 Gy/day to 59.4 Gy; Arm D, single-fraction irradiation as in Arm C plus DFMO given as in Arm B. Patients were followed for progression-free survival (PFS) and overall survival (OS), as well as for toxicity. Eligibility required histologically proven GBM, age > or =18, Karnofsky performance status (KPS) > or =60, and no prior chemotherapy or radiotherapy. Adjuvant chemotherapy was not used in this protocol.

RESULTS

A total of 231 eligible patients were enrolled. There were 95 men and 136 women with a median age of 57 years, and median KPS of 90. Extent of resection was total in 23, subtotal in 152, and biopsy only in 56 patients. The 4 arms were balanced with respect to age, KPS, and extent of resection. Times to event measurements are from date of diagnosis. Median OS and PFS were 40 and 19 weeks for Arm A; 42 and 22 weeks for Arm B; 37 and 16 weeks for Arm C; and 44 and 19 weeks for Arm D (p = 0.48 for survival; p = 0.32 for PFS). Comparison of the 2 arms treated with DFMO to the 2 arms without DFMO revealed no difference in OS (37 weeks vs. 42 weeks, p = 0.12) or PFS and thus no benefit to the use of DFMO. Comparison of the 2 standard fractionation arms to the 2 accelerated hyperfractionation arms also resulted in no difference in OS (42 weeks vs. 41 weeks, p = 0.75) or PFS, showing no benefit to accelerated hyperfractionated irradiation.

CONCLUSION

In this prospective Phase III study, no survival or PFS benefit was seen with accelerated hyperfractionated irradiation to 70.4 Gy, nor was any benefit seen with DFMO as a radiosensitizer. Standard fractionated irradiation to 59.4 Gy remains the treatment of choice for newly diagnosed patients with glioblastoma multiforme.

A preliminary study of the prognostic value of proton magnetic resonance spectroscopic imaging in gamma knife radiosurgery of recurrent malignant gliomas

OBJECTIVE

The goal of this study was to investigate the use of proton magnetic resonance spectroscopic imaging as a prognostic indicator in gamma knife radiosurgery of recurrent gliomas.

METHODS

Thirty-six patients with recurrent gliomas were studied with proton magnetic resonance spectroscopic imaging at the time of radiosurgery, and with conventional magnetic resonance imaging examinations at regular time intervals until the initiation of a new treatment strategy. Patients were categorized on the basis of their initial spectroscopic results, and their performance was assessed in terms of change in contrast-enhancing volume, time to further treatment, and survival.

RESULTS

The trends in the overall population were toward more extensive increase in the percent contrast-enhancing volume, a decreased time to further treatment, and a reduced survival time for patients with more extensive initial metabolic abnormalities. Statistical analysis of the subpopulation of patients with glioblastoma multiforme found a significant increase in relative contrast-enhancing volume (P < 0.01, Wilcoxon signed-rank test), a decrease in time to further treatment (P < 0.01, log-rank test), and a reduction in survival time (P < 0.01, log-rank test) for patients with regions containing tumor-suggestive spectra outside the gamma knife target, compared with patients exhibiting spectral abnormalities restricted to the gamma knife target. Further studies are needed to establish statistical significance for patients with lower-grade lesions and to confirm the results observed in this study.

CONCLUSION

The pretreatment spectroscopic results provided information that was predictive of outcome for this patient pool, both in local control (change in contrast-enhancing volume) and global outcome (time to further treatment and survival). This modality may have an important role in improving the selection, planning, and treatment process for glioma patients.

Radiosurgery for brain metastases: is whole brain radiotherapy necessary?

PURPOSE

Because whole brain radiotherapy (WBRT) may cause dementia in long-term survivors, selected patients with brain metastases may benefit from initial treatment with radiosurgery (RS) alone reserving WBRT for salvage as needed. We reviewed results of RS +/- WBRT in patients with newly diagnosed brain metastasis to provide background for a prospective trial.

METHODS AND MATERIALS

Patients with single or multiple brain metastases managed initially with RS alone vs. RS + WBRT (62 vs. 43 patients) from 1991 through February 1997 were retrospectively reviewed. The use of upfront WBRT depended on physician preference and referral patterns. Survival, freedom from progression (FFP) endpoints, and brain control allowing for successful salvage therapy were measured from the date of diagnosis of brain metastases. Actuarial curves were estimated using the Kaplan-Meier method. Analyses to adjust for known prognostic factors were performed using the Cox proportional hazards model (CPHM) stratified by primary site.

RESULTS

Survival and local FFP were the same for RS alone vs. RS + WBRT (median survival 11.3 vs. 11.1 months and 1-year local FFP by patient 71% vs. 79%, respectively). Brain FFP (scoring new metastases and/or local failure) was significantly worse for RS alone vs. RS + WBRT (28% vs. 69% at 1 year; CPHM adjustedp = 0.03 and hazard ratio = 0.476). However, brain control allowing for successful salvage of a first failure was not significantly different for RS alone vs. RS + WBRT (62% vs. 73% at 1 year; CPHM adjusted p = 0.56).

CONCLUSIONS

The omission of WBRT in the initial management of patients treated with RS for up to 4 brain metastases does not appear to compromise survival or intracranial control allowing for salvage therapy as indicated. A randomized trial of RS vs. RS + WBRT is needed to assess survival, quality of life, and cost in good-prognosis patients with newly diagnosed brain metastases.

Gamma knife radiosurgery for malignant melanoma brain metastases

PURPOSE

To evaluate the efficacy and toxicity of gamma knife radiosurgery in the treatment of melanoma metastases to the brain.

PATIENTS AND METHODS

We retrospectively reviewed 55 patients with single or multiple intracranial melanoma metastases treated at the University of California, San Francisco, with gamma knife radiosurgery from 1991 through 1995. Sixteen patients were treated with gamma knife radiosurgery for recurrence following previous radiation therapy, 11 received radiosurgery as a boost to whole-brain radiation therapy, and 28 had radiosurgery alone for initial management of brain metastases. The median minimum radiosurgery tumor dose for 140 treated lesions was 19 Gy (range, 10-22 Gy) prescribed at the 35% to 90% isodose contour (median, 50%). The median total target volume per patient was 6.1 cc (range, 0.25-28.3 cc).

RESULTS

With a median follow-up of 75 weeks in living patients, the median survival times were 35 weeks overall: 35 weeks for patients with solitary metastases versus 33 weeks for those with multiple metastases. A factor that was significant in univariate analysis of survival was total target volume treated. This parameter remained significant on multivariate analysis. The actuarial median freedom from progression analyzed by lesion for 113 lesions in 46 patients with imaging follow-up was 89 weeks with 6-month and 1-year actuarial freedom from progression rates of 89% (95% confidence interval, 80%-95%) and 77% (95% confidence interval, 62%-87%). In univariate analysis, improved freedom from progression was associated with smaller target volume treated, smaller maximum diameter, or higher prescribed dose. Four patients (7%) developed acute Radiation Therapy Oncology Group grade > or = 2 morbidity, and five patients (9%) developed late grade > or = 2 morbidity.

DISCUSSION

Median survival and freedom from progression in patients treated with radiosurgery for melanoma metastatic to the brain are comparable to results in published radiosurgery series of grouped histologies. For melanoma patients, total intracranial tumor volume appears to be of greater prognostic significance than the absolute number of metastases treated. We conclude that gamma knife radiosurgery is effective and should be considered among various management strategies.

Survival benefit of hyperthermia in a prospective randomized trial of brachytherapy boost +/- hyperthermia for glioblastoma multiforme

PURPOSE

To determine if adjuvant interstitial hyperthermia (HT) significantly improves survival of patients with glioblastoma undergoing brachytherapy boost after conventional radiotherapy.

METHODS AND MATERIALS

Adults with newly-diagnosed, focal, supratentorial glioblastoma < or = 5 cm in diameter were registered postoperatively on a Phase II/III randomized trial and treated with partial brain radiotherapy to 59.4 Gy with oral hydroxyurea. Those patients whose tumor was still implantable after teletherapy were randomized to brachytherapy boost (60 Gy at 0.40-0.60 Gy/h) +/- HT for 30 min immediately before and after brachytherapy. Time to progression (TTP) and survival from date of diagnosis were estimated using the Kaplan-Meier method.

RESULTS

From 1990 to 1995, 112 eligible patients were entered in the trial. Patient ages ranged from 21-78 years (median, 54 years) and KPS ranged from 70-100 (median, 90). Most commonly due to tumor progression or patient refusal, 33 patients were never randomized. Of the patients, 39 were randomized to brachytherapy ("no heat") and 40 to brachytherapy + HT ("heat"). By intent to treat, TTP and survival were significantly longer for "heat" than "no heat" (p = 0.04 and p = 0.04). For the 33 "no heat" patients and 35 "heat" patients who underwent brachytherapy boost, TTP and survival were significantly longer for "heat" than "no heat" (p = 0.045 and p = 0.02, respectively; median survival 85 weeks vs. 76 weeks; 2-year survival 31% vs. 15%). A multivariate analysis for these 68 patients adjusting for age and KPS showed that improved survival was significantly associated with randomization to "heat" (p = 0.008; hazard ratio 0.51). There were no Grade 5 toxicities, 2 Grade 4 toxicities (1 on each arm), and 7 Grade 3 toxicities (1 on "no heat" and 6 on the "heat" arm).

CONCLUSION

Adjuvant interstitial brain HT, given before and after brachytherapy boost, after conventional radiotherapy significantly improves survival of patients with focal glioblastoma, with acceptable toxicity.

Interstitial brachytherapy for malignant brain tumors

For nearly 20 years, interstitial brachytherapy has been used as adjuvant treatment for malignant brain tumors in both prospective clinical trials and as part of standard therapy. Numerous publications analyzing the results of this treatment seem to indicate an improvement in median survival for highly selected patients. Some newly diagnosed glioblastoma multiforme, recurrent malignant glioma, brain metastases and possibly low grade gliomas seem to benefit. While Iodine-125 (I-125) remains the most popular radionuclide for brachytherapy, there is a recent move away from temporary high-activity implants to permanent low-activity implants. This review article will concentrate on the results from the University of California, San Francisco, as well as recent series published since 1990. In spite of the increased availability of radiosurgery, interstitial brachytherapy still has a place in the management of these difficult tumors.

Radiation therapy and hydroxyurea followed by the combination of 6-thioguanine and BCNU for the treatment of primary malignant brain tumors

PURPOSE

This study was designed to evaluate a combined modality treatment for malignant gliomas using radiation therapy with a radiosensitizer and an adjuvant chemotherapy regimen designed to modify resistance to BNCU.

METHODS AND MATERIALS

Patients were eligible if they were 15 years of age or older, and had newly diagnosed glioblastoma multiforme (GBM), or anaplastic glioma (AG). Treatment consisted of external beam radiotherapy given to a dose of 60 Gy using a single daily fraction Monday to Friday. Concurrent hydroxyurea at a dose of 300 mg/m2 every 6 h every other day was given during radiation. Following radiotherapy, patients were then treated with BCNU and 6-Thioguanine (6TG). The 6-TG was given by mouth every 6 h for 12 doses prior to BCNU. Patients were initially treated with 60 mg/m2/dose of 6TG, with escalation to a maximum dose of 100 mg/m2/dose. The primary study end points were time to tumor progression and survival.

RESULTS

A total of 245 eligible patients were enrolled from 1/18/88 to 12/26/91. The histologic subtypes included 135 GBM, and 110 with AG (103 with anaplastic astrocytoma, 7 with high-grade mixed oligoastrocytoma). For the GBM group, the median time to tumor progression (TTP) and median survival were 33 (95% CI 26, 39) and 56 (95% CI 49, 69) weeks, respectively. For the AG group the median TTP was 282 weeks (95% lower confidence bound = 155 weeks). Median survival for this group has not been reached (95% lower confidence bound = 284 weeks) with a median follow-up for surviving patients of 298 weeks. A proportional hazards model was used to look at potential prognostic factors for survival, including initial Karnofsky Performance Scale (KPS), age, and extent of surgery, as well as dose of 6TG. Higher KPS, and lower age, predicted for longer survival (p < 0.01, < 0.001) in GBM patients; lower age was significant (p = 0.05) for AG cases. A higher (greater than 95 mg/m2) or lower dose of 6TG was not statistically significant in this model.

CONCLUSIONS

This therapy was no more effective in patients with GBM than other reported series. In patients with malignant gliomas other than GBM, prolonged progression-free and overall survival is noted, without a median survival reached at the time of this report. In this subset of AG patients, survival is comparable to recent studies using halogenated prymidines during radiation and Procarbazine, CCNU, and Vincristine (PCV) as adjuvant chemotherapy.

Volume MRI and MRSI techniques for the quantitation of treatment response in brain tumors: presentation of a detailed case study

Patients with primary brain tumors may be considered for several different treatments during the course of their disease. Assessments of disease progression and response to therapy are typically performed by visual interpretation of serial MRI examinations. Although such examinations provide useful morphologic information, they are unable to reliably distinguish active tumor from radiation necrosis. This poses a particular problem in the assessment of response to localized radiation therapies such as gamma knife radiosurgery. In this paper, we present methodology for evaluating changes in tissue morphology and metabolism based on serial volumetric MRI and magnetic resonance spectroscopic imaging (MRSI) examinations. Registration and quantitative analysis of these data provide measurements of the temporal and spatial distributions of gadolinium enhancement and of N-acetylasparate, choline, creatine, and lactate/lipid. The key features of this approach and the potential clinical benefits are illustrated by a detailed analysis of six serial MRI/MRSI examinations and three serial 1-[F-18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) studies on a patient with a recurrent anaplastic astrocytoma.

Serial proton magnetic resonance spectroscopy imaging of glioblastoma multiforme after brachytherapy

The utility of three-dimensional (3-D) proton magnetic resonance spectroscopy (1H-MRS) imaging for detecting metabolic changes after brain tumor therapy was assessed in a serial study of 58 total examinations of 12 patients with glioblastoma multiforme (GBM) who received brachytherapy. Individual proton spectra from the 3-D array of spectra encompassing the lesion showed dramatic differences in spectral patterns indicative of radiation necrosis, recurrent or residual tumor, or normal brain. The 1H-MRS imaging data demonstrated significant differences between suspected residual or recurrent tumor and contrast-enhancing radiation-induced necrosis. Regions of abnormally high choline (Cho) levels, consistent with viable tumor, were detected beyond the regions of contrast enhancement for all 12 gliomas. Changes in the serial 1H-MRS imaging data were observed, reflecting an altered metabolism following treatment. These changes included the significant reduction in Cho levels after therapy, indicating the transformation of tumor to necrotic tissue. For patients who demonstrated subsequent clinical progression, an increase in Cho levels was observed in regions that previously appeared either normal or necrotic. Several patients showed regional variations in response to brachytherapy as evaluated by 1H-MRS imaging. This study demonstrates the potential of noninvasive 3-D 1H-MRS imaging to discriminate between the formation of contrast-enhancing radiation necrosis and residual or recurrent tumor following brachytherapy. This modality may also allow better definition of tumor extent prior to brachytherapy by detecting the presence of abnormnal metabolite levels in nonenhancing regions of solid tumor.

Interstitial brachytherapy procedures for brain tumors

Promising results have been obtained using brachytherapy in the treatment of brain tumors. Very low-dose rate brachytherapy (60-100 Gy given at 0.05-0.10 Gy/h) has been used for low-grade gliomas, resulting in 5- and 10-year survival probabilities of 85% and 83% for pilocytic astrocytomas and 61% and 51% for grade II astrocytomas. Only 2.6% of patients had symptomatic radiation necrosis. For faster-growing high-grade gliomas, temporary implants delivering about 60 Gy at 0.40-0.60 Gy/h are generally used. The largest series have reported median survival times of 12-13 months after brachytherapy for recurrent malignant gliomas and 18-19 months after diagnosis of primary glioblastomas treated with external beam radiotherapy and brachytherapy boost. A recent prospective, randomized trial demonstrated significantly improved survival for high-grade glioma patients who had brachytherapy boost. However, over 50% of patients who undergo brachytherapy for malignant gliomas require reoperation for tumor progression and/or radiation necrosis. Strategies are under development to improve local control without increasing radiation toxicity.

Neuropsychological sequelae of medulloblastoma in adults

PURPOSE

To investigate the neuropsychological consequences of medulloblastoma in adults.

METHODS

Patients 18 years of age or older who had medulloblastoma and at least 3 years of disease-free survival were eligible. A battery of tests was conducted to assess global intellectual functioning, verbal ability, visuospatial ability, memory, reasoning, and academic proficiency. For the verbal memory performance, each patient was matched with two normal controls selected on the basis of age, sex, and level of education.

RESULTS

Review of the Neuro-Oncology database revealed 24 patients eligible for the study. Of these, 10 patients (6 good-risk and 4 poor-risk) agreed to participate; 7 patients were lost to follow-up; 5 lived too far away to come to the testing site, and 2 refused testing. There were four men and six women; their mean age was 36.5 years at testing and 29.9 years at surgical diagnosis. Mean dose of whole brain radiation was 34.5 Gy. Mean interval between diagnosis and testing was 79.1 months. Test results demonstrated below average intelligence quotients (mean intelligence quotient 90.2; range 67-103) and specific deficits in memory, reasoning, visuospatial ability, and arithmetic.

CONCLUSION

Adults with medulloblastoma in a prolonged disease-free status may suffer significant cognitive deficits. We recommend further controlled, prospective studies to evaluate cognitive outcomes in this patient population in the hope that interventional strategies could be developed, or treatment modified to minimize such toxicities.

Radiosurgery for brain metastases: relationship of dose and pattern of enhancement to local control

PURPOSE

This study aimed to analyze dose, initial pattern of enhancement, and other factors associated with freedom from progression (FFP) of brain metastases after radiosurgery (RS).

METHODS AND MATERIALS

All brain metastases treated with gamma-knife RS at the University of California, San Francisco, from 1991 to 1994 were reviewed. Evaluable lesions were those with follow-up magnetic resonance or computed tomographic imaging. Actuarial FFP was calculated using the Kaplan-Meier method, measuring FFP from the date of RS to the first imaging study showing tumor progression. Controlled lesions were censored at the time of the last imaging study. Multivariate analyses were performed using a stepwise Cox proportional hazards model.

RESULTS

Of 261 lesions treated in 119 patients, 219 lesions in 100 patients were evaluable. Major histologies included adenocarcinoma (86 lesions), melanoma (77), renal cell carcinoma (21), and carcinoma not otherwise specified (17). The median prescribed RS dose was 18.5 Gy (range, 10-22) and the median tumor volume was 1.3 ml (range, 0.02-30.9). The initial pattern of contrast enhancement was homogeneous in 68% of lesions, heterogeneous in 12%, and ring-enhancing in 19%. The actuarial FFP was 82% at 6 months and 77% at 1 year for all lesions, and 93 and 90%, respectively, for 145 lesions receiving > or = 18 Gy. Multivariate analysis showed that longer FFP was significantly associated with higher prescribed RS dose, a homogeneous pattern of contrast enhancement, and a longer interval between primary diagnosis and RS. Adjusted for these factors, adenocarcinomas had longer FFP than melanomas. No significant differences in FFP were noted among lesions undergoing RS for recurrence after prior radiotherapy (119 lesions), RS alone as initial treatment (45), or RS boost (55).

CONCLUSION

A minimum prescribed radiosurgical dose > or = 18 Gy yields excellent local control of brain metastases. The influence of pattern of enhancement on local control, a new finding in this retrospective analysis, needs to be confirmed.

Stereotactic radiosurgery for malignant melanoma to the brain

This article offers support for using radiosurgery in the treatment of patients with melanoma brain metastases. Although patients with multiple metastases may fare somewhat worse than patients with single metastases, the difference is not statistically significant. The only significant prognostic factor that we were able to identify was smaller total target volume (favorable factor), although further study with longer follow-up and more patients may reveal other factors. Radiosurgery is appealing to patients and physicians because it is noninvasive and requires minimal hospitalization and recovery. Gamma Knife therapy offers patients a rapid method for achieving local control, which may be particularly important for patients who would otherwise be considered for specific protocols (such as some using IL-2) which preclude enrollment unless intracranial disease is controlled. We conclude that stereotactic radiosurgery is an effective treatment modality, with acceptable toxicity, for patients with either solitary or multiple melanoma metastases to the brain.

Gamma knife for glioma: selection factors and survival

PURPOSE

To determine factors associated with survival differences in patients treated with radiosurgery for glioma.

METHODS AND MATERIALS

We analyzed 189 patients treated with Gamma Knife radiosurgery for primary or recurrent glioma World Health Organization (WHO) Grades 1-4.

RESULTS

CONCLUSION

The median minimum tumor dose was 16 Gy (8-30 Gy) and the median tumor volume was 5.9 cc (1.3-52 cc). Brachytherapy selection criteria were satisfied in 65% of patients. Median follow-up of all surviving patients was 65 weeks after radiosurgery. For primary glioblastoma patients, median survival from the date of pathologic diagnosis was 86 weeks if brachytherapy criteria were satisfied and 40 weeks if they were not (p = 0.01), indicating that selection factors strongly influence survival. Multivariate analysis showed that increased survival was associated with five variables: lower pathologic grade, younger age, increased Karnofsky performance status (KPS), smaller tumor volume, and unifocal tumor. Survival was not found to be significantly related to radiosurgical technical parameters (dose, number of isocenters, prescription isodose percent, inhomogeneity) or extent of preradiosurgery surgery. We developed a hazard ratio model that is independent of the technical details of radiosurgery and applied it to reported radiosurgery and brachytherapy series, demonstrating a significant correlation between survival and hazard ratio.

CONCLUSIONS

Survival after radiosurgery for glioma is strongly related to five selection variables. Much of the variation in survival reported in previous series can be attributed to differences in distributions of these variables. These variables should be considered in selecting patients for radiosurgery and in the design of future studies.

Factors influencing survival after gamma knife radiosurgery for patients with single and multiple brain metastases

PURPOSE

Radiosurgery has been reported to yield high local control rates for brain metastases. However, further work is needed to define which subgroups of patients may benefit from this treatment modality.

PATIENTS AND METHODS

We reviewed 116 patients who underwent stereotactic radiosurgery for initial management or recurrence of solitary or multiple brain metastases from September 1991 through December 1994 at the University of California, San Francisco. Survival time and time to local-regional failure were calculated using the Kaplan-Meier method. Univariate and multivariate analyses were performed using the Cox proportional hazards model.

RESULTS

Median survival was 40 weeks from radiosurgery. In multivariate analysis, smaller total tumor volume, absence of extracranial metastases, higher Karnofsky score, and age < or = 70 had a positive effect on survival. In patients initially managed for brain metastases, the addition of whole brain radiotherapy to radiosurgery had no significant effect on survival. Although the presence of multiple metastases was associated with a significantly worse survival rate in patients initially managed with radiosurgery in univariate analysis, it was not as a significant factor in multivariate analysis. An analysis of patients within this series treated with radiosurgery who would have been eligible for Patchell's study on the role of surgery in the treatment of solitary brain metastasis revealed a favorable median survival of 70 weeks.

CONCLUSIONS

We conclude that radiosurgical treatment of brain metastases results in survival times that compare favorably with the historic experience in patients treated with whole brain radiotherapy alone or with surgical resection. In patients presenting initially with brain metastases, radiosurgery alone may yield survival results equivalent to radiosurgery with whole brain radiotherapy, but intracranial control and quality of life also need to be evaluated. Also, the presence of multiple brain metastases should not be a contraindication for the use of radiosurgery given the good survival achieved with such patients in this series. Each such case should therefore be evaluated based on other factors such as patient's age, Karnofsky score and systemic disease.

Reirradiation of primary CNS tumors

PURPOSE

Primary central nervous system (CNS) tumors are seldom reirradiated due to toxicity concerns and sparse clinical data regarding efficacy.

METHODS AND MATERIALS

We retrospectively reviewed 34 patients with primary brain tumors retreated with fractionated external beam irradiation at the University of California, San Francisco from 1977-1993. Tumors included 15 medulloblastomas, 10 high-grade gliomas, 7 low-grade gliomas, and 2 meningiomas.

RESULTS

Initial course of radiation was radical in intent for all patients. Median age at initial diagnosis was 19.8 years (range: 3.6-67). Median interval between radiation courses was 16.3 months (range: 3.8-166). Median Karnofsky Performance Status (KPS) prior to reirradiation was 80 (range: 40-100). Reirradiation volumes overlapped previous treatment in 30 patients and were nonoverlapping in 4 patients. Fractionation schemes used were hyperfractionated in 17, conventionally fractionated in 9, and hypofractionated in 8. Cumulative maximum overlap dose within the CNS ranged from 43.2-111 Gy (median: 79.7 Gy). Retreatment was completed as planned in 27 out of 34 patients and modified or aborted in 7 (four tumor progression on retreatment, three patient request). As measured from the time of retreatment median progression free and overall survival was 3.3 and 8.3 months. Clinical and radiographic indices were stabilized or improved in about half of patients evaluable at a median of 3 months postretreatment. Complications (early or late) potentially attributable to retreatment were noted in 10 of 34 (29%) of patients. Overt necrosis was noted in 3 of 34 (9%) of patients and the actuarial risk of necrosis was 22% at 1 year following retreatment.

CONCLUSIONS

Reirradiation of primary central nervous system tumors was associated with only modest palliative and survival benefits in this retrospective review. Difficulties separating toxicity due to retreatment vs. tumor progression and limited patient survival following retreatment preclude definite conclusions regarding the safety of this practice.

Radiotherapy for cerebral metastases

Whole brain radiotherapy (WBRT) for patients with unresected brain metastases results in symptomatic response in about 50% of patients and improvement in median survival to 3 to 6 months. Most patients with brain metastases are appropriately treated with a conventional palliative course of 30 Gy in 10 fractions over 2 weeks, although accelerated hyperfractionation with 32 Gy to the whole brain plus a boost to at least 54.4 Gy at 1.6 Gy twice daily yields better results for patients with solitary metastases. Patients with a life-expectancy of greater than 6 months should receive at most that or equal to 2.0 Gy per fraction to minimize the risk of radiation-induced leukoencephalopathy and dementia. Patients with good performance status, absent or controlled primary tumor, and no extracranial metastases might benefit from surgical resection or radiosurgery (with or without adjunctive WBRT) to improve local control.

Interstitial brachytherapy for intracranial metastases

In large medical centers, the availability of radiosurgery has relegated brachytherapy to a lesser role in the treatment of newly diagnosed solitary brain metastases. However, the treatment planning in radiosurgery is complex, and in some case the hardware is prohibitively expensive; low or high dose rate brachytherapy requires only a stereotactic frame, commercially available software, and encapsulated radionuclides or newer tiny linear accelerators. Interstitial brachytherapy also remains an option for the treatment of recurrent solitary metastases when other forms of treatment have failed. This article reviews the radiobiology of low and high dose rate interstitial brachytherapy, the University of California San Francisco (UCSF) results using iodine-125 implants, and early experience with the photon radiosurgery system (PRS) at Massachusetts General Hospital for the treatment of brain metastases.

Long-term follow-up after high-activity 125I brachytherapy for pediatric brain tumors

A retrospective review including long-term follow-up (4.6-12.0 years) was performed of all 28 pediatric patients who underwent high-activity 125I brachytherapy at the University of California, San Francisco, for primary or recurrent brain tumors from 1980 until 1991. There were 4 glioblastomas, 11 high-grade nonglioblastoma multiforme (NGM) malignant gliomas, 10 contrast-enhancing low-grade NGM, 2 choroid plexus carcinomas, and 1 rhabdomyosarcoma. The 13 survivors included 7 of 8 patients with primary high-grade NGM, 2 of 3 patients with primary low-grade NGM, and 3 of 7 patients with recurrent low-grade NGM. Necrosis (with or without tumor) was identified in 17 of 22 reoperated patients. The mean Karnofsky performance status was 88 +/- 9 at the time of brachytherapy, 87 +/- 7 at 3 years, and 87 +/- 9 in 11 patients alive at 6-12 years. Brachytherapy is a useful modality for treating selected pediatric brain tumors, and although focal necrosis is a common sequela, it does not tend to have a major impact on the Karnofsky performance status, if the implant site is amenable to reoperation.

Radiosurgery for hemangioblastoma: results of a multiinstitutional experience

PURPOSE

Between June 1988 and June 1994. 38 hemangioblastomas were treated with stereotactic radiosurgery (SR) at three SR centers to evaluate the efficacy and potential toxicity of this therapeutic modality as an adjuvant or alternative treatment to surgical resection.

METHODS AND MATERIALS

SR was performed using either a 201-cobalt source unit or a dedicated SR linear accelerator. Of the 18 primary tumors treated, 16 had no prior history of surgical resection and were treated definitively with SR and two primary lesions were subtotally resected and subsequently treated with SR. Twenty lesions were treated with SR after prior surgical failure (17 tumors) or failure after prior surgery and conventional radiotherapy (three tumors). Eight patients were treated with SR for multifocal disease (total, 24 known tumors). SR tumor volumes measured 0.05 to 12 cc (median: 0.97 cc). Minimum tumor doses ranged from 12 to 20 Gy (median: 15.5 Gy).

RESULTS

Median follow-up from the time of SR was 24.5 months (range: 6-77 months). The 2-year actuarial over-all survival was 88 +/- 15% (95% confidence interval). Two-year actuarial freedom from progression was 86 +/- 12% (95% confidence interval). The median tumor volume of the lesions that failed to be controlled by SR was 7.85 cc (range: 3.20-10.53 cc) compared to 0.67 cc (range: 0.05-12 cc) for controlled lesions (p - 0.0023). The lesions that failed to be controlled by SR received a median minimum tumor dose of 14 Gy (range: 13-17 Gy) compared to 16 Gy (range: 12-20 Gy) for controlled lesions (p = 0.0239). Seventy-eight percent of the surviving patients remained neurologically stable or clinically improved. There were no significant permanent complications directly attributable to SR.

CONCLUSIONS

This report documents the largest experience in the literature of the use of SR in the treatment of hemangioblastoma. We conclude that SR: (a) controls the majority of primary and recurrent hemangioblastomas; (b) offers the ability to treat multiple lesions in a single treatment session, which is particularly important for patients with Von Hippel-Lindau Syndrome; and that (c) better control rates are associated with higher doses and smaller tumor volumes.

Direct-coupled interstitial ultrasound applicators for simultaneous thermobrachytherapy: a feasibility study

This study presents the design and performance evaluation of interstitial ultrasound applicators designed specifically for thermal therapy with simultaneous brachytherapy. The applicator consists of a multielement array of piezoceramic tubular radiators, each with separate power control, surrounded by thin layers of electrically-insulating and biocompatible coatings (< 2.6 mm OD). A catheter which is compatible with remote afterloaders and standard brachytherapy technology forms the inner lumen. These 'direct-coupled interstitial ultrasound applicators' (DCIUA's) are placed within the tumour or target region, with the coated transducer surface forming the outer wall of the implant catheter. Thermocouple sensors embedded in the coating over each transducer can be used for continuous monitoring of the tissue/applicator interface temperatures for feedback control of power to each transducer segment. Theoretical acoustic power deposition and corresponding temperature distributions from thermal simulations have demonstrated that the radius of effective heating is highly dependent upon the acoustic efficiency of the piezoceramic transducers, with effective heating extending > 1 - 1.5 cm radially for typical DCIUA applicators that are 60-65% efficient. This exceeds the effective heating radius of both thermal conduction and RF heating technologies. Measurements with prototype multielement ultrasound applicators have demonstrated acoustic efficiencies between 60 and 65% and beam distributions which are fairly uniform and collimated to the transducer axial length. Thermal dosimetry measurements within in vivo tissues have demonstrated controllable therapeutic temperature rises at 1 - 1.5 cm radial depth from the applicators, which were in agreement with the simulations. This study demonstrates that direct-coupled ultrasound applicators, designed without an active cooling mechanism in order to accommodate the insertion of radiation sources, are practicable for simultaneous thermobrachytherapy and promises to give more adjustable heating patterns than current alternative techniques.

Demonstration of brachytherapy boost dose-response relationships in glioblastoma multiforme

PURPOSE

To evaluate brachytherapy dose-response relationships in adults with glioblastoma undergoing temporary 125I implant boost after external beam radiotherapy.

METHODS AND MATERIALS

Since June 1987, orthogonal radiographs using a fiducial marker box have been used to verify brain implant source positions and generate dose-volume histograms at the University of California, San Francisco. For adults who underwent brachytherapy boost for glioblastoma from June 1987 through December 1992, tumor volumes were reoutlined to ensure consistency and dose-volume histograms were recalculated. Univariate and multivariate analysis of various patient and treatment parameters were performed evaluating for influence of dose on freedom from local failure (FFLF) and actuarial survival.

RESULTS

Of 102 implant boosts, 5 were excluded because computer plans were unavailable. For the remaining 97 patients, analyses with adjustment for known prognostic factors (age, KPS, extent of initial surgical resection) and prognostic factors identified on univariate testing (adjuvant chemotherapy) showed that higher minimum brachytherapy tumor dose was strongly associated with improved FFLF (p = 0.001). A quadratic relationship was found between total biological effective dose and survival, with a trend toward optimal survival probability at 47 Gy minimum brachytherapy tumor dose (corresponding to about 65 Gy to 95% of the tumor volume); survival decreased with lower or higher doses. Two patients expired and one requires hospice care because of brain necrosis after brachytherapy doses > 63 Gy to 95% of the tumor volume with 60 Gy to > 18 cm3 of normal brain.

CONCLUSION

Although higher minimum tumor dose was strongly associated with better local control, a brachytherapy boost dose > 50-60 Gy may result in life-threatening necrosis. We recommend careful conformation of the prescription isodose line to the contrast enhancing tumor volume, delivery of a minimum brachytherapy boost dose of 45-50 Gy in conjunction with conventional external beam radiotherapy, and reoperation for symptomatic necrosis.

Radiation response and survival time in patients with glioblastoma multiforme

The determine the value of radiographically assessed response to radiation therapy as a predictor of survival in patients with glioblastoma multiforme (GBM), the authors studied a cohort of 301 patients who were initially treated according to uniform clinical protocols. All patients had newly diagnosed supratentorial GBM and underwent the maximum safe resection followed by external- beam radiation treatment (60 Gy in standard daily fractions or 70.4 Gy in twice-daily fractions of 160 cGy). The radiation response and survival rates were assessable in 222 patients. The extent of resection and the immediate response to radiation therapy were highly correlated with survival, both in a univariate analysis and after correction for age and Karnofsky performance scale (KPS) score in a multivariate Cox model (p< 0.001 for radiation response and p=0.04 for extent of resection). A subgroup analysis suggested that neuroimaging obtained within 3 days after surgery served as a better baseline for assessment of radiation response than images obtained later. Imaging obtained within 3 days after completion of a course of radiation therapy also provided valid radiation response scores. The impact of the radiographically assessed radiation response on survival time was comparable to that of age or KPS score. This information is easily obtained early in the course of the disease, may be of value for individual patients, and may also have implications for the design and analysis of trials of adjuvant therapy for GBM, including volume-dependent therapies such as radiosurgery or brachytherapy.

Bromodeoxyuridine labeling index in glioblastoma multiforme: relation to radiation response, age, and survival

PURPOSE

Various measures of the rate of tumor cell proliferation have been found to predict survival in patients with intracerebral gliomas. We correlated the bromodeoxyuridine labeling index (BrdUrd LI) with the response to radiation therapy, survival, and known prognostic factors in a series of patients with glioblastoma multiforme (GM) to test its utility as a prognostic factor.

METHODS AND MATERIALS

The BrdUrd LI was determined in 200 newly diagnosed intracranial GMs. Age and sex were known for all patients. The response to radiation therapy was determined in 116 patients by comparing neuroimaging studies obtained before and after external beam radiation therapy. Survival was analyzed in 64 patients who were treated according to two consecutive prospective clinical protocols.

RESULTS

The median BrdUrd LI was 6.5% (mean, 7.2%; range, 1.1-25.4%). The BrdUrd LI did not correlate significantly with age, sex, radiation response, or survival. Age and Karnofsky performance score were independent prognostic factors in our cohort.

CONCLUSION

The proliferative rate as measured by BrdUrd LI was not a prognostic factor in our GM cohort. The BrdUrd LI did not correlate significantly with known prognostic factors in GM. There was no significant relationship between BrdUrd LI and radiation response.

Gamma knife radiosurgery in children

52 pediatric patients were treated with radiosurgery at the University of California, San Francisco. Arteriovenous malformations were treated in 27 patients. Complete obliteration was noted in 4 of 12 patients imaged more than 2 years after radiosurgery. Arteriovenous malformation rebleed was noted in 1 patient. Symptomatic T2 changes were noted in 2 patients. Among 29 neoplasms treated in 25 patients, local control was noted in 5 of 7 low-grade gliomas, 5 of 14 high-grade gliomas, 4 of 5 craniopharyngiomas and 3 of 3 sarcomas. Three patients treated for neoplasms developed necrosis after radiosurgery.

Radiation therapy for primary intracranial germ-cell tumors

PURPOSE

To evaluate the diagnosis, therapy, and survival of patients with intracranial germ-cell tumors. To define the role of prophylactic craniospinal irradiation and chemotherapy necessary to impact on survival.

METHODS AND MATERIALS

Forty-eight patients with surgically confirmed or suspected primary intracranial germ-cell tumors treated at UCSF between 1968-1990 were reviewed. Thirty-four patients had a pathologic diagnosis, including 24 germinomas, 3 malignant teratomas, 2 choriocarcinomas, 1 embryonal carcinoma, 1 endodermal sinus tumor, and 3 mixed tumors. Information obtained included histology, location, cerebrospinal fluid (CSF) cytology, alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin (B-HCG), metastatic evaluation, radiation details, survival, and sites of failure. Minimum follow-up time was 2 years and ranged to a maximum of 24 years, with a median of 8 years.

RESULTS

Median age at diagnosis was 16 years with 36 males and 12 females. Ten of 32 patients had elevated B-HCG at diagnosis; 6 of 29 had elevations of AFP. Cerebrospinal fluid cytology was negative in 35 of 36 patients evaluated; myelography or spinal MRI was positive in only 1 of 31 patients studied. Five-year actuarial disease-free survival after irradiation was 91% for germinomas, 63% for unbiopsied tumors, and 60% for nongerminoma germ-cell tumors with doses of 50-54 Gy to the local tumor site with or without whole-brain or whole-ventricular irradiation. Routine prophylactic cranio-spinal axis irradiation was not given with a spinal only failure rate of 2%. Eleven of 48 patients have expired, with an actuarial 5-year survival rate of 100% for germinomas, 79% for nonbiopsied tumors, and 80% for nongerminoma germ-cell tumors.

CONCLUSION

With complete diagnostic craniospinal evaluation, spinal irradiation is not necessary. Cure rates for germinomas are excellent with irradiation alone. Multidrug chemotherapy is necessary with irradiation for nongerminoma germ-cell tumors. Histology is the most important prognostic factor; therefore, all patients should have surgical conformation of their diagnosis so that appropriate treatment can be given.

Fetal dose estimates for radiotherapy of brain tumors during pregnancy

PURPOSE

To determine clinically the fetal dose from irradiation of brain tumors during pregnancy and to quantitate the components of fetal dose using phantom measurements.

METHODS AND MATERIALS

Two patients received radiotherapy during pregnancy for malignant brain tumors. Case 1 was treated with opposed lateral blocked 10 x 15 cm fields and case 2 with 6 x 6 cm bicoronal wedged arcs, using 6 MV photons. Fetal dose was measured clinically and confirmed with phantom measurements using thermoluminescent dosimeters (TLDs). Further phantom measurements quantitated the components of scattered dose.

RESULTS

For case 1, both clinical and phantom measurements estimated fetal dose to be 0.09% of the tumor dose, corresponding to a total fetal dose of 0.06 Gy for a tumor dose of 68.0 Gy. Phantom measurements estimated that internal scatter contributed 20% of the fetal dose, leakage 20%, collimator scatter 33%, and block scatter 27%. For case 2, clinical and phantom measurements estimated fetal dose to be 0.04% of the tumor dose, corresponding to a total fetal dose of 0.03 Gy for a tumor dose of 78.0 Gy. Leakage contributed 74% of the fetal dose, internal scatter 13%, collimator scatter 9%, and wedge scatter 4%.

CONCLUSIONS

When indicated, brain tumors may be irradiated to high dose during pregnancy resulting in fetal exposure < 0.10 Gy, conferring an increased but acceptable risk of leukemia in the child, but no other deleterious effects to the fetus after the fourth week of gestation. For our particular field arrangements and linear accelerators, internal scatter contributed a small component of fetal dose compared to leakage and scatter from the collimators and blocks, and 18 MV photons resulted in a higher estimated fetal dose than 6 MV photons due to increased leakage and collimator scatter. These findings are not universal, but clinical and phantom TLD measurements estimate fetal dose accurately for energies < 10 MV and should be taken for each pregnant patient considered for treatment to confirm and document acceptable dose.

Large effect of age on the survival of patients with glioblastoma treated with radiotherapy and brachytherapy boost

A retrospective review was undertaken to study the influence of age on the survival of patients undergoing brachytherapy boost for glioblastoma multiforme. From February 1981 through December 1992, 159 adults with primary glioblastoma multiforme underwent high-activity iodine-125 brain implant boost after external beam radiotherapy. There were 98 men and 61 women, ranging in age from 18 to 73 years (median, 52 yr). Karnofsky performance scores ranged from 70 to 100 (median, 90). Surgery before radiotherapy consisted of biopsy in 7% of patients, subtotal resection in 66%, and gross total resection in 27%. External beam radiotherapy doses ranged from 39.6 to 76.8 Gy, with 91% of patients receiving 59.4 to 61.2 Gy. Brachytherapy doses ranged from 35.7 to 66.5 Gy (median, 55.0 Gy) at 0.30 to 0.70 Gy per hour (median, 0.43 Gy/h). Reoperations were performed in 81 patients (51%). Information on quality of life was available for 13 of the 14 living 3-year survivors; 10 patients were steroid independent, and mean Karnofsky performance scores had decreased from 92 at the time of brachytherapy to 75 at the last follow-up. Univariate and multivariate analyses showed that age was the most important parameter influencing survival (P < 0.0005). The nine patients 18 to 29.9 years old had a 3-year survival probability of 78 +/- 14% (median survival was not yet reached at the time of this report), with a follow-up of 145 to 511 weeks in living patients (median, 322 wk).(ABSTRACT TRUNCATED AT 250 WORDS)

Pattern of recurrence of medulloblastoma after low-dose craniospinal radiotherapy

PURPOSE

We retrospectively evaluated relapse of medulloblastoma after low- or high-dose craniospinal radiotherapy, and after conventional or hyperfractionated posterior fossa irradiation.

METHODS AND MATERIALS

Ninety-two pediatric patients were treated postoperatively since 1970 at the University of California, San Francisco. Until 1989, we employed conventional fractionation with low (< or = 30 Gy) or high-dose craniospinal fields and low-dose (< or = 56 Gy) posterior fossa boosts. Recently, hyperfractionation delivered low- or high-dose to the craniospinal axis and high-dose to the posterior fossa. Most patients treated after 1979 received chemotherapy.

RESULTS

Median follow-up was 70 months. Five-year disease-free survival was 36% (22% for poor-risk vs. 59% for good-risk patients). Five-year overall survival was 52% (43% for poor vs. 68% for good-risk). Neither the dose to the posterior fossa nor the craniospinal axis was statistically related to recurrence. Failure in the posterior fossa occurred despite boosts greater than 56 Gy. Females, over the age of 6 years, had significantly better relapse-free survival than males of the same age. Six of the 54 patients who relapsed were long-term survivors.

CONCLUSIONS

Low-dose craniospinal radiotherapy, where the majority of patients received chemotherapy, was not associated with increased failure. High-dose posterior fossa hyperfractionation did not improve control. Long-term survival was noted in a number of patients after relapse. We recommend 60 Gy or greater with conventional fractions to the primary area, and continued study of low-dose craniospinal irradiation with adjuvant chemotherapy.

Patterns of recurrence of glioblastoma multiforme after external irradiation followed by implant boost

PURPOSE

To study patterns of recurrence in patients with focal primary glioblastoma treated on Northern California Oncology Group protocol 6G-82-2 including surgery, focal external beam radiotherapy (59.4-60 Gy) with oral hydroxyurea followed by temporary brain implant with high-activity iodine-125 sources (50 Gy), and six cycles of chemotherapy with procarbazine, lomustine, and vincristine.

METHODS AND MATERIALS

Serial brain imaging scans were available for review in 25 of 34 patients with glioblastoma who underwent brain implant boost. Of 381 scans performed between the date of diagnosis and the date of death or last follow-up, 362 (95%) were re-reviewed. Disease progression was scored as local (within 2 cm of the implant site), separate within the brain parenchyma (> or = 2 cm from the implant site), subependymal, or systemic. Both initial and subsequent failures were scored.

RESULTS

Three patients are 5-year survivors, without evidence of disease, at 267, 292, and 308 weeks. Of the 22 initial sites of failure, 17 (77%) were local, three (14%) were separate brain lesions (one of which was due in retrospect to multicentric disease at diagnosis), one (5%) subependymal, and one (5%) systemic. Five patients with local failure later had other sites of failure, including a separate brain lesion in 1, subependymal spread in 3, and both in 1. One patient with separate brain failure later had local progression and then subependymal spread.

CONCLUSION

Although there was a significant risk of separate brain lesions or subependymal spread over time, local tumor progression was the predominant pattern of failure.