CNS germ cell tumors: pattern of failure and effects of radiation volume.

This retrospective study was conducted to evaluate local control and overall survival after radiotherapy for patients with intracranial germ cell tumors and to investigate the influence of irradiated field on treatment outcome. Thirty-two patients with surgically confirmed or suspected primary intracranial germ cell tumors (GCT) treated at the Division of Therapeutic Radiology and Oncology, Chiang Mai University, Chiang Mai, Thailand between January 1988 and December 1999 were reviewed Seven patients were not included in the analysis of treatment outcome and survival due to incompleteness of radiation treatment or death before the end of treatment. The median follow up time of 39.5 months (range from 2.3 months to 136.1 months). Median age at diagnosis was 16.5 years with 23 males and 9 females. Patients were irradiated to the primary tumor with an adequate margin in 7 patients, to the whole brain with a cone down boost in 8 patients. Craniospinal irradiation (CSI) was performed in 10 patients. For the 25 evaluable patients, 5 year overall survival was 86.4%. Five-year disease free survival was 72.9%. Five year overall survival rates were 83.1% and 90.0% for the germinoma and nonbiopsied group. (p-value = 0. 6052). Routine prophylactic CSI was not given with a spinal only failure rate of 33.3%. Five-year overall survival were 85.7%, 87.5%, 85.7% for CSI, whole brain irradiation with boost and local field irradiation (p-value = 0.9037). Five-year disease free survival were 85.7%, 72.9%, 85.7% for CSI, WBRT, and local field (p-value = 0. 6403). This retrospective study suggests that definitive radiation therapy is effective in controlling germinoma, and cure rates are excellent with irradiation alone. Craniospinal irradiation can eliminate the risk of relapse especially in patients who had incomplete diagnostic craniospinal evaluation.

A feasibility study of 18F-fluorodeoxyglucose positron emission tomography targeting and simultaneous integrated boost for intensity-modulated radiosurgery and radiotherapy.

OBJECT: The authors hypothesized that the efficacy of intensity-modulated radiation therapy (IMRT) can be enhanced by selectively increasing the radiation dose to the biologically active positron emission tomography (PET)-documented positive tumor subregions while simultaneously maintaining the overall clinically established target dose. METHODS: The authors undertook a feasibility study to evaluate IMRT PET/computerized tomography (CT) protocol for boost treatment in selected cancer patients. Prior to treatment, FDG-PET and CT scans were acquired using an integrated PET/CT scanner, ensuring accurate correlation between image sets. After acquisition, tumor volume and objects-at-risk (OARs) were outlined on the CT scans; any PET-positive tumor subregions were similarly outlined. Daily dosages of 1.8 to 2 Gy were prescribed to tumor volume and the margin whereas additional dosages of 10 to 20% were delivered to PET-positive subregions. Dosage-volume histogram-derived constraints were used in inverse planning to specify the desired dose to one or more PET-positive tumor subregions, CT-delineated tumor volume, and OARs. The IMRT treatment was delivered using a micromultileaf collimator. Simultaneous integrated boost radiation was successfully delivered using IMRT with PET/CT planning. Excellent dose conformality was achieved in the tumor volume and the dose to PET-positive tumor subregions was increased while minimizing the dose to OARs. CONCLUSIONS: When coupled with IMRT, PET/CT scanning allows dose escalation to biologically active subregions within the tumor volume. Further study is needed to determine if dose escalation to FDG-PET-active sites correlates with improved treatment outcome. Finally, in extracranial sites, PET scanning should only be performed with a dedicated PET/CT device because present image fusion technologies are inadequate for accurately registering deformable objects.

Linear accelerator radiosurgery using 90 gray for essential trigeminal neuralgia: results and dose volume histogram analysis.

OBJECTIVE: To evaluate treatment of essential trigeminal neuralgia with 90 Gy delivered by a linear accelerator dedicated to radiosurgery. METHODS: This is a retrospective case series of 25 patients with essential trigeminal neuralgia treated from March 1999 to March 2001. All were treated with 90 Gy by means of a 5-mm collimator directed to the nerve root entry zone. Patient follow-up (range, 8-52 mo; median, 18 mo) was completed by an uninvolved party. Dose volume histograms of the brainstem were developed for the 20, 30, and 50% isodose lines by means of radiosurgery planning software. RESULTS: All patients obtained good to excellent pain relief with treatment. Nineteen (76%) of 25 patients achieved excellent pain relief (pain-free without medication). Six patients (24%) achieved good pain relief (50-90% reduction of pain with or without medication). Median time to pain relief was 2 months. Eight patients (32%) experienced relapse 4 to 13 months after treatment. Eight patients (32%) developed facial numbness, but none developed painful numbness. Mean brainstem volume within the 50% isodose line and occurrence of numbness was statistically significant (P = 0.03). There was no correlation between brainstem volume treated and outcome. CONCLUSION: Dedicated linear accelerator-based stereotactic radiosurgery that uses a 5-mm collimator to deliver 90 Gy to the nerve root entry zone is a safe and effective method for the treatment of essential trigeminal neuralgia. Care should be taken to limit brainstem volume included in the 50% isodose line in the treatment plan to avoid facial numbness.

Dedicated linear accelerator radiosurgery for the treatment of trigeminal neuralgia.

OBJECT: In this study the authors evaluate the efficacy of and complications associated with dedicated linear accelerator (LINAC) radiosurgery for trigeminal neuralgia (TN). METHODS: Between August 1995 and February 2001, 60 patients whose median age was 66.1 years (range 45-88 years) were treated with dedicated LINAC radiosurgery for TN. Forty-one patients (68.3%) had essential TN, 12 (20%) had secondary facial pain, and seven (11.7%) had atypical features. Twenty-nine patients (48.3%) had undergone previous surgical procedures. Radiation doses varied between 70 and 90 Gy (mean 83.3 Gy) at the isocenter, with the last 35 patients (58.3%) treated with a 90-Gy dose. A 5-mm collimator was used in 45 patients (75%) and a 7.5-mm collimator in 15 patients (25%). Treatment was focused at the nerve root entry zone. At last follow up (mean follow-up period 23 months, range 2-70 months), 36 (87.8%) of the 41 patients with essential TN had sustained significant pain relief (good plus excellent results). Twenty-three patients (56.1%) were pain free without medication (excellent outcome), 13 (31.7%) had a 50 to 90% reduction in pain with or without medication (good outcome), and five (12.2%) had minor improvement or no relief. Of 12 patients with secondary facial pain, significant relief was sustained in seven patients (58.3%); worse results were found with atypical pain. Fifteen (25%) of the 60 patients experienced new numbness postprocedure; no other significant complications were found. Pain relief was experienced at a mean of 2.7 months (range 0-12 months). CONCLUSIONS: Dedicated LINAC radiosurgery is a precise and effective treatment for TN.

Prospective study of stereotactic radiosurgery without whole brain radiotherapy in patients with four or less brain metastases: incidence of intracranial progression and salvage radiotherapy.

This prospective study was conducted to evaluate the treatment outcome after stereotactic radiosurgery (SRS) alone with special attention to its influence on intracranial freedom from progression (FFP), local control, time to whole brain radiotherapy (WBRT), and survival. Forty-one patients with brain metastases who met the inclusion criteria were enrolled in this prospective cohort and treated by SRS alone between January 1998 and September 2001. The overall local control rate was 76%. The one year actuarial intracranial FFP was 33%. Ten patients (24%) had relapse at treated site. Twenty-three patients (56%) had intracranial progression with a median time of 4.25 months (1-24.6). Salvage radiotherapy was given in 21 patients (51%). Only 12 (29%) patients required WBRT with the median time to WBRT after SRS of 4.85 months. Nine patients (22%) underwent additional SRS at the median time of 5 months after the first procedure. The median survival was 10 months. At the time of follow up, 16 patients (39%) were still alive with a range of 6-31 months. This prospective study suggests that the omission of WBRT in the initial treatment of patients with SRS for four or less brain metastases may allow up to 70% of patients to avoid WBRT.