Radiotherapy For Glioma Research Articles

Same, better, or worse? Neurocognitive effects of radiotherapy for low-grade gliomas remain unknown

Low-grade gliomas (LGG) are a heterogeneous group of tumours that occur primarily in young adults. LGGs are slowly progressive, often have few symptoms initially, and frequently undergo anaplastic transformation. The prognosis of patients with LGG is primarily affected by their age and the pathological type of the LGG. Many questions remain about the management of LGG, including the roles of aggressive surgical resection and chemotherapy and the optimum timing of radiotherapy.1 Although radiotherapy can cause neurocognitive deficits it can also improve cognitive function by having a positive treatment effect on the tumour.

Combined Radio- and Chemotherapy of Brain Tumours in Adult Patients

In order to examine the current standards of care regarding combined radio- and chemotherapy for adult patients with brain tumours, a review was carried out of recent studies examining surgery, radiotherapy and chemotherapy in high-grade glioma, medulloblastoma and primary central nervous system lymphoma. The integration of the oral cytotoxic agent temozolomide into current treatment protocols of postoperative combination therapy with radiation and drugs in high-grade glioma is discussed. In glioblastoma, the landmark phase III trial by the European Organisation for Research and Treatment of Cancer and the National Cancer Institute of Canada has defined the current standard of care. Attempts to optimise the schedule of temozolomide administration and to combine this regimen with additional agents are currently ongoing. Additional trials are examining whether temozolomide–radiotherapy combination regimens should also be the standard of care in patients with anaplastic glioma. The role of postsurgery procarbazine, lomustine, and vincristine (PCV) in addition to radiotherapy in anaplastic glioma with oligodendroglial features is controversial, as two randomised trials failed to show improved survival, despite longer progression-free survival. In medulloblastoma, no comparable landmark trial exists and therefore combined radiochemotherapy must be considered investigational. In primary central nervous system lymphoma, high-dose methotrexate-based chemotherapy is the cornerstone of therapy and the value of consolidation radiotherapy for patients achieving a complete response is controversial, even in younger patients who have a lower risk of neurotoxicity than older patients. The challenges associated with brain tumour treatment remain formidable, but rationally designed clinical trials are gradually leading to improved outcomes.

MGMT expression in low-grade gliomas

e13001 Background: To evaluate the expression of MGMT in low-grade gliomas, and explore the relationship between its expression and the histological type of the tumour and the corresponding MRI characteristics. Methods: We assessed 389 low-grade gliomas (182 astrocytomas, 145 oligoastrocytomas, 61 oligodendrocytomas) with immunohistochemistry staining. We also recorded the preoperational MRI criteria such as tumor volume on T2 image, enhancing volume, tumor location, and relationship with ventricles. Results: The expression of MGMT in astrocytomas, oligoastrocytomas, and oligocytomas were 1.67 ± 0.78, 1.41 ± 0.86,1.44 ± 0.78, respectively. Significant stronger expression of MGMT was observed in astrocytomas than oligoastrocytomas and oligodendrocytomas (t = 3.00, p = 0.03), but no significant difference was observed between the latter two (t = 0.28, p = 0.78). MGMT expression level was significantly correlated with the enhancing volume of the tumor (r = -0.605, p = 0.002), but did not correlate with the total tumor volume (p = 0.504). Conclusions: MGMT is more strongly expressed in tumors of solely astrocyte component, and its expression level is negatively correlated with the extent of blood-brain barrier disruption. This suggest that MGMT may contribute to the tumor resistance to radiotherapy and chemotherapy in low-grade gliomas. No significant financial relationships to disclose.

Dosimetry study of a phase II multiple-dose intracavitary administration of 131I-TM601 in adult patients with recurrent high-grade glioma

e13006 Background: Postoperative radiotherapy for glioma has been shown to improve survival with increased radiation doses. Dose escalation of external beam radiotherapy or brachytherapy is limited by normal brain radionecrosis. Radiolabeled targeting molecules can deliver localized radiation to tumor and reduce normal brain radionecrosis. TM601, or synthetic Chlorotoxin, is a peptide derived from scorpion venom that specifically binds to tumor cells. Here we report dosimetry results of an imaging sub-study of a phase II trial, in which weekly doses of 131I-TM601 were infused into surgically created tumor resection cavities for 3 or 6 weeks. Methods: Five out of 76 patients treated in a phase II trial were imaged after receiving 1, 3, or 6 doses of 40 mCi/0.8 mg 131I-TM601 intracavitarily. For each imaging study, 5 sequential SPECT images (1–168 hour) were registered with MRI to determine the 131I-TM601 radiation dose to the 2-cm tumor cavity margin. Five sequential body scans were also acquired to determine 131I-TM601 radiation dose to extra-cranial organs. Results: 131I-TM601 is a rapidly penetrating and clearing radiolabeled peptide. The median residual activity in the cavity at 7 days post injection was 8.4%. Median radiation dose to the cavity margin was 121 cGy/mCi and ranged 52- 338 cGy/mCi in 5 subjects. The median coefficient of variation (intra-patient inter-fraction) for the 2-cm margin dose was 14.7% and ranged 7.1–18.9%. Median tumor cavity volume was 11.4 mL, and ranged 5.2 - 35.5 mL. There was no observed correlation between the 2-cm margin dose and the cavity volume. Median radiation dose to thyroid, kidneys, red marrow, and body was 8.3, 1.3, 0.4, and 0.6 cGy/mCi, respectively. Conclusions: Radiation dose ratio for 2-cm cavity margin-to-normal tissues was quite high. While intra-patient reproducibility was relatively good, cumulative effect of the residual activity was only meaningful within a week. These results support the multi-dose fractionation scheme for 131I-TM601 to minimize normal tissue toxicity, including radiation necrosis, and extend continuous irradiation to clinical or sub-clinical residual tumor cells after surgery. [Table: see text]

Three-Dimensional Conformal Radiotherapy, Temozolomide Chemotherapy, and High-Dose Fractionated Stereotactic Boost in a Protocol-Driven, Postoperative Treatment Schedule for High-Grade Gliomas

No available scientific report deals with high-dose (> or = 70 Gy) radiotherapy plus temozolomide chemotherapy (TMZ CHT) in high-grade gliomas. The survival results of a protocol-driven, postoperative treatment schedule are reported here to contribute to the discussion on this issue. Uniform criteria were prospectively adopted for case selection during the period 1993-2006 in the management of 123 patients, and we progressively introduced three-dimensional conformal radiotherapy (3D-CRT, 60 Gy), TMZ CHT and a high-dose (70 Gy) stereotactic boost (HDSRT) in the treatment schedule. Palliative radiotherapy was delivered by whole brain irradiation (WBI, 50 Gy) for bulky tumors, whereas radical irradiation was performed with 3D-CRT throughout the study period. Two periods of accrual are considered: 36 patients were treated before 31 December 1999 (29.25%) and 87 (70.75%) after 1 January 2000. This subdivision was due to the implementation of HDSRT hardware and TMZ CHT from January 2000. The median overall survival was 13 months and the 1-, 2- and 3-year survival rates were 53%, 19.5% and 11.6%, respectively. The differences in survival related to the treatment variables were highly significant, both in univariate and multivariate analysis. The median survival and 1-, 2- and 3-year survival rates in the palliative WBI group were 9.75 months and 37%, 2%, and 0%, respectively; in the 3D-CRT group 17.25 months and 64%, 34%, and 15%, respectively; in the TMZ CHT concomitant with radiotherapy group 20 months and 61%, 39%, and 21%, respectively; in the TMZ CHT concomitant with and sequential to radiotherapy group 25.75 months and 84%, 54%, and 26%, respectively, and in the HDSRT group 22 months and 72%, 48%, and 37%, respectively. No symptomatic radiation necrosis occurred in any of the groups. The results reported here are generally better than those reported in the literature. The selection of patients on the basis of favorable prognostic factors and suitability to the currently available, aggressive postoperative treatment resources can be the mainstay for improving therapeutic results. In particular, the new treatment option reported here (HDSRT in association with TMZ CHT) proved to be safe and effective in obtaining a relatively favorable outcome.

A comparative study on the therapeutic efficacy of conventional radiotherapy and three dimensional conformal radiotherapy for malignant glioma

Objective:To compare the efficacy of conventional radiotherapy and three dimensional conformal radiotherapy (3D-CRT) for malignant glioma retrospectively. Methods: From January 1997 to May 2007, 152 patients with malignant glioma received postoperative radiotherapy at our hospital. Patients were classified into two groups according to the radiotherapy techniques. Group A (n=85) received conventional whole brain or subtotal brain irradiation at 36-40 Gy followed by a boost of 20 Gy to the tumor bed. Group B (3D-CRT group, n=67) were given 50-54 Gy of irradiation in the clinical target volume (CTV) and 60 Gy of irradita-tion in the gross tumor volume (GTV). GTV was defined as the high signal area on T2 weighted FLAIR MRI image, and CTV was defined as GTV plus a 2-cm margin. The fraction dose for both conventional chemotherapy and 3D-CRT was 2.0 Gy/fx, once a day, five times per week. The efficacies of both ratiotherapy were compared and the failure mode was analyzed. Results: The 3-year overall survival rates were 22.9% and 31.9% in group A and group B, respectively(χ2=1.01, P=0.31). Incidence of increased intracra-nial pressure were 47.1% and 31.3% in group A and group B, respectively(χ2=3.95, P=0.04). All the tumor recurrence was detected within the range of GTV and CTV in 45 patients in group B.Conclusion: 3D-CRT reduces the incidence of radiation-induced high intracranial pressure of malignant glioma patients compared with conventional radiotherapy. The irradiation volume including the high signal area on T2 FLAIR MR imaging plus a 2-cm margin is feasible in 3D-CRT.

(18)F]Fluoroethyltyrosine- positron emission tomography-guided radiotherapy for high-grade glioma

BackgroundTo compare morphological gross tumor volumes (GTVs), defined as pre- and postoperative gadolinium enhancement on T1-weighted magnetic resonance imaging to biological tumor volumes (BTVs), defined by the uptake of 18F fluoroethyltyrosine (FET) for the radiotherapy planning of high-grade glioma, using a dedicated positron emission tomography (PET)-CT scanner equipped with three triangulation lasers for patient positioning.MethodsNineteen patients with malignant glioma were included into a prospective protocol using FET PET-CT for radiotherapy planning. To be eligible, patients had to present with residual disease after surgery. Planning was performed using the clinical target volume (CTV = GTV ∪ BTV) and planning target volume (PTV = CTV + 20 mm). First, the interrater reliability for BTV delineation was assessed among three observers. Second, the BTV and GTV were quantified and compared. Finally, the geometrical relationships between GTV and BTV were assessed.ResultsInterrater agreement for BTV delineation was excellent (intraclass correlation coefficient 0.9). Although, BTVs and GTVs were not significantly different (p = 0.9), CTVs (mean 57.8 ± 30.4 cm3) were significantly larger than BTVs (mean 42.1 ± 24.4 cm3; p < 0.01) or GTVs (mean 38.7 ± 25.7 cm3; p < 0.01). In 13 (68%) and 6 (32%) of 19 patients, FET uptake extended ≥ 10 and 20 mm from the margin of the gadolinium enhancement.ConclusionUsing FET, the interrater reliability had excellent agreement for BTV delineation. With FET PET-CT planning, the size and geometrical location of GTVs and BTVs differed in a majority of patients.

Can radiation induce pituitary tumors? Giant prolactinoma after radiation exposure

Radiation is a well-known etiology for many CNS tumors, including meningiomas, sarcomas and gliomas. However, occurrence of pituitary adenoma after radiation exposure is rare. We report a 21-year-old man with a pituitary adenoma, who was treated with post-operative radiotherapy for pontine glioma at 6 years of age. The role of radiation exposure in the etiology of pituitary adenoma is discussed, along with a literature review of radiation-induced tumors.

18F Fluoroethyltyrosine-Positron Emission Tomography-guided Radiotherapy for High-grade Glioma

18F Fluoroethyltyrosine-Positron Emission Tomography-guided Radiotherapy for High-grade Glioma

Volumetric Modulated Arc Therapy (VMAT) Reduces Treatment Time and Improves Dosimetry Compared to Conventional Intensity Modulated Radiotherapy (IMRT) for Frontal and Temporal High-grade Gliomas (HGG)

Volumetric Modulated Arc Therapy (VMAT) Reduces Treatment Time and Improves Dosimetry Compared to Conventional Intensity Modulated Radiotherapy (IMRT) for Frontal and Temporal High-grade Gliomas (HGG)

188Re-loaded lipid nanocapsules as a promising radiopharmaceutical carrier for internal radiotherapy of malignant gliomas

Lipid nanocapsules (LNC) entrapping lipophilic complexes of (188)Re ((188)Re(S(3)CPh)(2)(S(2)CPh) [(188)Re-SSS]) were investigated as a novel radiopharmaceutical carrier for internal radiation therapy of malignant gliomas. The present study was designed to evaluate the efficacy of intra-cerebral administration of (188)Re-SSS LNC by means of convection-enhanced delivery (CED) on a 9L rat brain tumour model. Female Fischer rats with 9L glioma were treated with a single injection of (188)Re-SSS LNC by CED 6 days after cell implantation. Rats were put into random groups according to the dose infused: 12, 10, 8 and 3 Gy in comparison with blank LNC, perrhenate solution (4 Gy) and non-treated animals. The radionuclide brain retention level was evaluated by measuring (188)Re elimination in faeces and urine over 72 h after the CED injection. The therapeutic effect of (188)Re-SSS LNC was assessed based on animal survival. CED of (188)Re perrhenate solution resulted in rapid drug clearance with a brain T (1/2) of 7h. In contrast, when administered in LNC, (188)Re tissue retention was greatly prolonged, with only 10% of the injected dose being eliminated at 72 h. Rat median survival was significantly improved for the group treated with 8 Gy (188)Re-SSS LNC compared to the control group and blank LNC-treated animals. The increase in the median survival time was about 80% compared to the control group; 33% of the animals were long-term survivors. The dose of 8 Gy proved to be a very effective dose, between toxic (10-12 Gy) and ineffective (3-4 Gy) doses. These findings show that CED of (188)Re-loaded LNC is a safe and potent anti-tumour system for treating malignant gliomas. Our data are the first to show the in vivo efficacy of (188)Re internal radiotherapy for the treatment of brain malignancy.

Enhancement of Glioma Radiotherapy and Chemotherapy Response With Targeted Antibody Therapy Against Death Receptor 5

TRA-8 is an agonistic mouse monoclonal antibody that binds to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptor 5, which induces apoptosis in cancer cells through a caspase-8-dependent mechanism. We investigated the ability of TRA-8 to augment the radiotherapy (RT) and chemotherapy response of human glioma cells in vitro and in vivo. The in vitro cytotoxicity of TRA-8 and temozolomide (Tmz) or RT was examined using adenosine triphosphate-dependent viability and clonogenic survival assays with five glioma cell lines. Death receptor 5 expression was determined by flow cytometry. In vivo studies included subcutaneous and intracranial xenograft models testing various combination treatments, including RT, Tmz, and TRA-8. TRA-8, combined with Tmz or RT, produced enhanced cytotoxicity against five glioma cell lines compared with the use of the individual agents alone. Death receptor 5 upregulation occurred in response to RT. Complete tumor regression in the subcutaneous experiments was the most common in animals that received combination therapy with TRA-8/Tmz/RT. TRA-8 enhanced tumor growth delay in combination with RT or Tmz. TRA-8 alone had limited activity against intracranial tumors. In contrast, the median survival of mice treated with TRA-8/Tmz/RT was significantly greater than the control or TRA-8-alone-treated mice. The median survival of the mice treated with TRA-8/Tmz/RT or chemoradiotherapy only was significantly greater than the control or TRA-8-treated mice. A trend toward improved survival was observed between TRA-8/Tmz/RT-treated and Tmz/RT-treated mice. These preliminary findings support the hypothesis that TRA-8 will augment the RT and chemotherapy response in gliomas. A humanized version of TRA-8 is being evaluated in a Phase II clinical trial.

Prospective single-arm study of 72 Gy hyperfractionated radiation therapy and combination chemotherapy for anaplastic astrocytomas

BackgroundDespite intensive multimodal treatment, outcome of patients with malignant glioma remains poor, and a standard dose of radiotherapy for anaplastic astrocytoma has not been defined. In the past RTOG study (83-02), the arm of 72 Gy hyperfractionated radiotherapy (HFRT) for malignant gliomas showed better outcome than the arms of higher doses (76.8 – 81.6 Gy) and the arms of lower doses (48 – 54.4 Gy). The purpose of this study is to verify the efficacy of this protocol.MethodsFrom July 1995, 44 consecutive eligible patients with histologically proven anaplastic astrocytoma were enrolled in this study (HFRT group). The standard regimen in this protocol was post-operative radiotherapy of 72 Gy in 60 fractions (1.2 Gy/fraction, 2 fractions/day) with concurrent chemotherapy (weekly ACNU). The primary endpoint was local control rate (LCR), and the secondary endpoints were overall survival (OS), progression-free survival (PFS) and late toxicity.ResultsThree-year OS of the HFRT group was 64.8% (95% confidence interval; 48.4–81.3%). Three-year PFS rate and LCR were 64.4% (95%CI: 48.4–80.3%) and 81.6% (95%CI: 69.2–94.8%), respectively.The number of failures at 5 years in the HFRT group were 14 (32%). The number of failures inside the irradiation field was only about half (50%) of all failures. One (2%) of the patients clinically diagnosed as brain necrosis due to radiation therapy.ConclusionThe results of this study suggested that 72 Gy HFRT seemed to show favorable outcome for patients with anaplastic astrocytoma with tolerable toxicity.

Delineation of Target Volume for Radiotherapy of High-Grade Gliomas by 99mTc-MIBI SPECT and MRI Fusion

Computed tomography (CT) and magnetic resonance imaging (MRI) are traditionally used for treatment planning of high-grade glioma. 99m Tc-methoxy-isobutyl-isonitrile (MIBI) single-photon emission computed tomography (SPECT) showed high sensitivity and specificity in literature series. In the present study, it was investigated how the information provided by 99m Tc-MIBI SPECT and MRI fusion could affect target delineation for radiotherapy of high-grade glioma. 21 patients with high-grade glioma were studied by MRI and 99m Tc-MIBI SPECT imaging. The gross tumor volume (GTV) was outlined on MRI (MRI-GTV) and SPECT images (SPECT-GTV). Three additional volumes were analyzed: the (MRI+SPECT)-GTV representing the whole amount of MRI-GTV plus SPECT-GTV, the (MRI&SPECT)-GTV identified by the overlapping region of MRI-GTV and SPECT-GTV, and the (SPECT/MRI)-GTV identified by the extension of SPECT-GTV outside MRI-GTV. MRI contrast-enhanced and 99m Tc-MIBI SPECT-positive lesions were found in all 21 patients. The average SPECT-GTV was slightly larger than the average MRI-GTV, with greater difference for resected than for unresected cases. The average increment of (MRI+SPECT)-GTV compared to MRI-GTV was 33%, being significantly higher for resected than for unresected cases (p = 0.006). The fusion of 99m Tc-MIBI SPECT and MRI significantly affected the delineation of the target volume identified by MRI alone.

Systematic review of the diagnostic accuracy of 201Tl single photon emission computed tomography in the detection of recurrent glioma

To determine the diagnostic accuracy of 201Tl SPECT in the detection of tumour recurrence in patients with previous radiotherapy for supratentorial glioma. The databases of PubMed and Embase were searched for relevant studies. Two reviewers independently selected and extracted data on study characteristics, quality and accuracy of studies. Studies were included if they comprised at least six eligible patients who underwent 201Tl SPECT (index test) and in whom (histo)pathological confirmation (reference test) of the suspected brain lesion was obtained. Because of the methodological and statistical heterogeneity of the included studies, a quantitative meta-analysis was not performed. Instead, for every individual study, the sensitivity, specificity and diagnostic odds ratio of 201Tl SPECT was calculated. Eight studies met the inclusion criteria. Only one was considered of high methodological quality. Methodological limitations referred most notably to blinding and patient selection. The diagnostic odds ratio was greater than 1 in all studies included, with a broad range (2-351), and relatively wide 95% confidence intervals. The sensitivity of 201Tl SPECT ranged from 0.43 to 1.00, and the specificity from 0.25 to 1.00. 201Tl SPECT seems a valuable method in the detection of tumour recurrence in patients treated with radiotherapy for supratentorial glioma. However, the evidence is not very robust because of the low quality and high heterogeneity of the studies included. Future studies are warranted to further explore the diagnostic potential of 201Tl SPECT, and to determine optimum thresholds for the detection of glioma recurrence.

Individual voxelwise dosimetry of targeted 90Y-labelled substance P radiotherapy for malignant gliomas

Substance P is the main ligand of neurokinin type 1 (NK-1) receptors, which are consistently overexpressed in malignant gliomas. The peptidic vector 111In/90Y-DOTAGA-substance P binds to these receptors and can be used for local treatment of brain tumours. Dosimetry for this interstitial brachytherapy has mainly been done using geometrical models; however, they often do not faithfully reproduce the in vivo biodistribution of radiopharmaceuticals, which is indispensable to correlate the deposited energy with clinical response. The aim of this study was to establish a reproducible dosimetry protocol for intratumoural radiopeptide therapy. For test and therapeutic injections, 2 MBq of 111In-substance P and 370-3,330 MBq of 90Y-substance P, respectively, were applied in 12 patients with malignant gliomas. Over a period of 24 h, serial SPECT scans were performed on a dual-head SPECT camera. The scans were acquired in a double-energy window technique together with 99mTc-ECD in order to co-register the dose distributions with a separately acquired, contrast-enhanced CT scan. Quantitative voxelwise dose distribution maps (in Gy/GBq) were computed from these data using a mono-exponential decay approach. Pre- and post-therapeutic values were compared. Agreement between pre- and post-therapeutic dosimetry was very good and delivered absolute dose values in Gy per injected GBq. In all patients, the pretherapeutic test injection together with the CT overlay technique could predict the precise localisation of dose deposition in an anatomical context. This protocol allows a precise pretherapeutic computation of the expected three-dimensional dose distribution and is clearly superior to the previously used dosimetry based on planar scintigraphic images. It has become an indispensable tool for planning intratumoural radiopeptide therapy in glioma patients.

Intensity-modulated radiotherapy (IMRT) and conventional three-dimensional conformal radiotherapy for high-grade gliomas: Does IMRT increase the integral dose to normal brain?

To determine whether intensity-modulated radiotherapy (IMRT) treatment increases the total integral dose of nontarget tissue relative to the conventional three-dimensional conformal radiotherapy (3D-CRT) technique for high-grade gliomas. Twenty patients treated with 3D-CRT for glioblastoma multiforme were selected for a comparative dosimetric evaluation with IMRT. Original target volumes, organs at risk (OAR), and dose-volume constraints were used for replanning with IMRT. Predicted isodose distributions, cumulative dose-volume histograms of target volumes and OAR, normal tissue integral dose, target coverage, dose conformity, and normal tissue sparing with 3D-CRT and IMRT planning were compared. Statistical analyses were performed to determine differences. In all 20 patients, IMRT maintained equivalent target coverage, improved target conformity (conformity index [CI] 95% 1.52 vs. 1.38, p < 0.001), and enabled dose reductions of normal tissues, including brainstem (D(mean) by 19.8% and D(max) by 10.7%), optic chiasm (D(mean) by 25.3% and D(max) by 22.6%), right optic nerve (D(mean) by 37.3% and D(max) by 28.5%), and left optic nerve (D(mean) by 40.6% and D(max) by 36.7%), p < or = 0.01. This was achieved without increasing the total nontarget integral dose by greater than 0.5%. Overall, total integral dose was reduced by 7-10% with IMRT, p < 0.001, without significantly increasing the 0.5-5 Gy low-dose volume. These results indicate that IMRT treatment for high-grade gliomas allows for improved target conformity, better critical tissue sparing, and importantly does so without increasing integral dose and the volume of normal tissue exposed to low doses of radiation.

Electrical spinal cord stimulation during radiotherapy and temozolomide in high grade gliomas. A phase II report

11510 Background: Ischemia-hypoxia in high grade gliomas (HGG) turns tumor cells more aggressive and more resistant to radiotherapy (RT) and temozolomide (TMZ). Higher glucose metabolism pre-treatment has been correlated with better response to TMZ using 18-FDG-PET. In preliminary works, we have reported that electrical spinal cord stimulation (SCS) can modify loco-regional oxygenation, blood flow and metabolism in HGG. The aim of this study was to evaluate tumor response and toxicity in HGG using SCS during RT plus TMZ. Methods: 10 patients (males/females: 8/2; median age: 51 years (30–68)) were enrolled in this trial. Tumors were 6 glioblastomas and 4 relapsed anaplastic gliomas. Diagnosis was after complete resection (1), subtotal resection (6), biopsy (1) or MRI + PET (2 relapsed HGG). Tetrapolar electrode for SCS was percutaneously inserted on the posterior surface of the cervical spinal cord at C2-C4 level. RT was at 2 Gy/fraction, 5 fractions/week, total dose 60 Gy (40 Gy in previously irradiated tumors). TMZ was administered at 75 mg/m2 daily during RT, followed by at least 6 cycles of adjuvant TMZ at 200 mg/m2. Tumor response was evaluated by CT and PET. Results: After concurrent RT+TMZ, CT showed: 5 partial response (PR), 3 complete response (CR), 2 stable disease (SD). After 6 adjuvant cycles of TMZ, CT (median 10 months after surgery) showed: 4 PR, 3 CR, 3 progression disease (PD). PET showed post-surgical residual tumor in the 9 evaluated patients. After 6 cycles of TMZ, PET showed: 4 CR, 2 PR (they obtained delayed CR after 12 and 18 cycles of TMZ), PD n = 2, and two patients without PET assessment (1 with PR in CT, and 1 without tumor in CT). For the study group median overall survival (OS) was 22 months (95% CI = 14–30) and for glioblastomas 16 months (95% CI = 6–26). For relapsed anaplastic gliomas mean OS was 37 months (95% CI = 22–52). One patient did not finish scheduled adjuvant TMZ and only one patient experienced hematological toxicity with neutropenia G-I and thrombopenia G-III. Conclusions: Electrical SCS during RT+TMZ did not increase toxicity. Preliminary data about tumor response and OS seem to be encouraging and they support further research. Supported by Grants: FUNCIS 03/09 and ISCiii, RTICCC C03/10. No significant financial relationships to disclose.

Post-operative concomitant radiochemotherapy in the treatment of primitive CNS high grade gliomas. A retrospective analysis

11528 Background: The authors analyse retrospectively the impact on tumour control and toxicity of concomitant radiotherapy (RT) and Temozolomide (TMZ) in high grade gliomas (HGG) of the CNS, in patients treated in the Clínica de Radioterapia do Porto - Portugal. Methods: This cohort represents all patients with HGG treated between January 2002 and January 2006, with concomitant RT a median total dose of 60 Gy, 2 Gy per treatment given once daily 5-days/week and TMZ 75mg/m2 for 42 days, followed by adjuvant treatment with TMZ 5-days schedule every 28 days (150 mg/m2 for the first cycle increased to 200mg/m2). The cohort was retrospectively analyzed for gender distribution, age, extent of surgical resection, initial KPS, median overall survival (OS) and haematological toxicity. Results: 23 with HGG (6 females, 17 males) were treated with concomitant RT (44–72 Gy) and TMZ followed by adjuvant TMZ; median age was 58 (ranging from 17–72); median KPS was 80 (ranging from 40–90); 3 patients had complete resection, 17 partial resection and 3 biopsy. All patients except one, who had treatment interruption for thrombocytopenia, completed the concomitant phase of treatment; 19 patients continued to received adjuvant treatment with TMZ (median number of cycles was 5 (ranging from 1–20). Median OS (measured from the date of diagnosis to the date of death) was 20.4 month and 1 yr OS was 54%. During concomitant phase, one patient had grade 3–4 thrombocytopenia. During the adjuvant TMZ therapy 4 patients had grade 3–4 haematological toxicity (anaemia: 1; thrombocytopenia: 1; leucopoenia and thrombocytopenia: 2). Conclusions: The results of concomitant RT+TMZ followed by TMZ in these patients with HGG showed values in accordance with the latest data published on literature for this association. Differences observed might be due to the small sample size.RT+TMZ followed by adjuvant TMZ is a well tolerated treatment with better results in median OS comparatively with previous results of RT only treatment in HGG. Treatment related toxicity was within acceptable levels, and this approach became routine practice in this set of patients. No significant financial relationships to disclose.

Optimization of combination therapy of arsenic trioxide and fractionated radiotherapy for malignant glioma

The primary objective was to optimize the combined treatment regimen using arsenic trioxide (ATO) and fractionated radiotherapy for the treatment of malignant glioma. Nude mice with human glioma xenograft tumors were treated with fractionated local tumor radiation of 250 cGy/fraction/day and 5 mg/kg ATO for 5-10 days. Time course experiments demonstrated that maximal tumor growth delay occurred when ATO was administered between 0 and 4 h after radiation. The combination treatment of ATO and radiation synergistically inhibited tumor growth and produced a tumor growth delay time of 13.2 days, compared with 1.4 days and 6.5 days for ATO and radiation alone (p < 0.01), respectively. The use of concurrent therapy of radiation and ATO initially, followed by ATO as maintenance therapy, was superior to the use of preloading with ATO before combined therapy and produced a tumor growth delay time of 22.7 days as compared with 11.7 days for the ATO preloading regimen (p < 0.01). The maintenance dose of ATO after concurrent therapy was effective and important for continued inhibition of tumor growth. The combined use of fractionated radiation and ATO is effective for the treatment of glioma xenograft tumors. ATO was most effective when administered 0-4 h after radiation without pretreatment with ATO. These results have important implications for the optimization of treatment regimen using ATO and fractionated radiotherapy for the treatment of brain tumors.