Changes in pulmonary function and their correlation with dose-volume parameters in patients undergoing stereotactic body radiotherapy for lung cancer.

It is desirable to estimate the degree of the decrease in pulmonary function before lung stereotactic body radiation therapy (SBRT) especially for patients with poor pulmonary function. The purpose of this study was to investigate whether decreases in pulmonary function after SBRT may be predicted from radiation dose-volume parameters. A total of 70 patients undergoing SBRT were evaluated for changes in pulmonary function. Of these, 67 had primary lung cancer and 3 had lung metastasis. Twenty-six (37%) patients had chronic obstructive pulmonary disease. Pulmonary function tests (PFTs) were performed shortly before and at 18-24 months after SBRT. Radiation pneumonitis was Grade 2 in 10 patients and Grade 3 in 1. Mean forced vital capacity (FVC) decreased from 2.67 to 2.51 L (P < 0.01) and mean forced expiratory volume in 1 s (FEV1) decreased from 1.80 to 1.72 L (P < 0.01). Planning target volume (PTV) was correlated with changes in FVC. Changes in percent predicted FVC were correlated with %V5Gy (% of lung volume receiving > 5 Gy) and %V40Gy. Although the correlation was not significant, the %V20Gy value was the closest to the percent reduction in predicted FVC; %V20Gy of 10% tended to be associated with ~10% reduction in predicted FVC. Patients with poor pulmonary function did not necessarily show greater decreases in each PFT parameter. Decreases in FVC and FEV1 were within previously reported ranges. PTV was associated with decreases in FVC. The %V20Gy value was closest to the percentage decrease in predicted FVC.

Dosimetric Comparison of Hypofractionated Multi-Beam Intensity-Modulated Radiation Therapy and Volumetric Modulated Arc Therapy With Flattened Beam and Flattening-Filter-Free Beam for Skull Base Meningioma Adjacent to Optic Pathways.

Background Since the optic pathways are the most vulnerable to radiation, the treatment of skull base tumors involving them is challenging. In this study simulation plans by multi-beam (MB) intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), both with the flattened beam (FB) and flattening-filter-free beam (FFF), were compared in terms of covering of the target and sparing of the optic pathways. Materials and methods Treatment planning was simulated by MB-IMRT with FB and FFF and by 2-rotational VMAT with FB and FFF in three cases of skull base meningioma [volume of the planned target volume (PTV; PTV margin=2 mm except for overlapping area with optic pathways or brainstem): 8.6 ml, 34.6 ml, and 55.3 ml respectively], which were treated previously by multi-fractionated MB-IMRT [45 Gy/18 fx. (fraction) with 7-, 6-, and 5-beam] using a conventional Novalis (BrainLAB, Tokyo, Japan) planned by iPlan (BrainLAB, Tokyo, Japan). In all three cases, the optic pathways were adjacent to the lesion. The reference CT with contouring data set of target volumes [gross tumor volume (GTV) and PTV] and OARs (organs at risk) was transferred from iPlan to Eclipse (Varian Medical Systems, Tokyo, Japan). In this study, hypofractionated radiation therapy by 30 Gy/5 fx. was designed; 95% dose (28.5 Gy/5 fx.) was prescribed to D95 (dose to 95% volume of PTV). Conformity index (CI), homogeneity index (HI, D5/D95), D[0.1 ml] (dose to 0.1 ml) for optic pathways, and D[1 ml] for brainstem and eyes, and V[20 Gy] (volume delivered with 20 Gy or more/5 fx.) of the whole brain were evaluated. Results The indices did not differ between FB and FFF, in either MB-IMRT or VMAT. Between MB-IMRT and VMAT, the indices were similar. The mean dose of PTV and HI was a little larger with MB-IMRT than with VMAT. D[0.1 ml] of the optic pathways and D[1 ml] of the ipsilateral eye were smaller with VMAT in all three cases. D[1 ml] of the brainstem was smaller with VMAT in two cases, though it was similar in one case. Conclusion Based on our findings, VMAT with FFF might be the optimal method to treat cases of skull base meningioma involving optic pathways. However, further studies involving more cases are required to arrive at a conclusive verdict.

Definitive Radiotherapy With SBRT or IMRT Boost for Breast Cancer: Excellent Local Control and Cosmetic Outcome.

The gold standard for breast cancer treatment is surgery, but many women may desire to avoid surgery if possible. The purpose of this study was to evaluate whether breast cancer could be cured with modern sophisticated radiation techniques with good cosmetic outcome. We have treated 18 patients with operable breast cancer by conventional whole-breast irradiation followed by stereotactic body radiotherapy (primary tumor only) or intensity-modulated radiotherapy (tumor plus axillary nodes) boost. The planned doses were 50 Gy in 25 fractions, 18 to 25.5 Gy in 3 fractions, and 20 Gy in 8 fractions, respectively, for the 3 modalities. Stereotactic body radiotherapy was delivered with 7 to 9 coplanar and noncoplanar fixed beams, and intensity-modulated radiotherapy was given by tomotherapy. Chemotherapy and/or hormone therapy was used depending on the stage and receptor status. In 9 recent patients, hydrogen peroxide was intratumorally injected twice a week before whole-breast irradiation. All treatments were well tolerable and there were no grade ≥3 toxicities. With a median follow-up period of 35 months (range, 8-120 months), only 1 patient developed local recurrence and 2 patients developed distant metastasis. Overall survival, progression-free survival, and local control rates were 93%, 85%, and 92%, respectively, at 3 years. In 50% of the patients, the irradiated breast became better rounded, and the position of the nipple of the irradiated breast became ≥1 cm higher compared to that of the unirradiated breast. Thus, the treated breasts may be more aesthetically favorable than before irradiation in these patients. This may become a treatment option for patients with operable breast cancer.

Stereotactic Radiotherapy for Intramedullary Spinal Arteriovenous Malformations.

Introduction Preliminary results of stereotactic radiotherapy (SRT) for spinal arteriovenous malformation (AVM) in five cases are presented.  Methods Two cases were male and three were female. Their median age was 32 years (range: 23 to 54 years). The spinal intramedullary AVMs were located in the cervical spine in three and in the thoracic spine in two. SRT with 20 Gy in four fractions was delivered to the nidus in every case. Results At the end of the median follow-up period of 5.5 years (range: 3 to 8.5 years), the neurological symptoms and signs were improved or unchanged as compared with before treatment, although a temporary adverse effect developed between a half year and one year after SRT in one case. The nidi were obliterated five and a half years after SRT in one case and three years after SRT in one. In the other three cases, the nidi were unchanged. Conclusion SRT with 20 Gy in four fractions was thought to be a safe treatment, though this study dealt with only a small number of patients with a short-term follow-up period.

Repeat stereotactic body radiotherapy (SBRT) for local recurrence of non-small cell lung cancer and lung metastasis after first SBRT.

BACKGROUND: This study evaluated the safety and efficacy of repeat SBRT for local recurrence of stage I non-small-cell lung cancer (NSCLC) and solitary lung metastasis. METHODS: Thirty-one patients with in-field local relapse of NSCLC (n = 23) or lung metastasis (n = 8) underwent repeat SBRT. All patients had grade 2 or lower radiation pneumonitis after the first SBRT. Local recurrence was diagnosed with CT and FDG-PET in 17 patients and by biopsy in 14. The median interval between the first and second SBRT was 18 months (range, 4-80). The first SBRT dose was mainly 48-52 Gy in 4 fractions (n = 25) according to the institutional protocols. Second SBRT doses were determined based on the tumor size and distance to organs at risk, and were mostly 48-52 Gy in 4 fractions (n = 13) or 60 Gy in 8 fractions (n = 13). RESULTS: At 3 years, overall survival and local control rates were 36 and 53%, respectively, for all 31 patients. Four patients showed no further recurrence for > 5 years (63-111 months) after the second SBRT. Radiation pneumonitis after the second SBRT was grade 2 in 4 patients, and no grade 3 pneumonitis was observed. CONCLUSION: Repeat SBRT was safe. Local control and survival rates were higher than expected. SBRT should be an important treatment option for local recurrence of NSCLC or lung metastasis after previous local SBRT. TRIAL REGISTRATION: This retrospective study was approved by the ethics committee of our institution (September, 2017; approval number: 27-10).

The Fate of Residual Tumor Masses That Persist After Stereotactic Body Radiotherapy for Solitary Lung Nodules: Will They Recur?

BACKGROUND: After stereotactic body radiotherapy (SBRT) to the lung, radiation pneumonitis and fibrotic changes often develop, and the tumor shadow usually becomes indistinguishable from the fibrotic shadow. Occasionally, however, a residual mass in patients with no or mild radiation pneumonitis will be observed on serial computed tomography (CT) scans. The purpose of the present study was to evaluate the fate of such residual masses and, if possible, to determine the types of tumor at increased risk of local recurrence. PATIENTS AND METHODS: A total of 50 patients (underlying disease: primary lung cancer in 45, local recurrence in 2, and metastasis in 3) were selected because they had been followed up for > 2 years or until death and had observable CT changes and measurable tumor size for > 1 year, regardless of the influence of radiation pneumonitis. The patients' outcomes were compared according to various patient and tumor characteristics, including the presence and absence of emphysema, tumor size, and tumor shrinkage rate. The median follow-up period was 52 months. RESULTS: Of the 50 patients, only 8 developed local recurrence. The local control rate was 81% at 3 years and 73% at 5 years. The local control rates were similar between patients with a high tumor shrinkage rate and those with a low rate. The patients with emphysema exhibited a lower local control rate. CONCLUSION: The persistence of lung masses for > 1 year after SBRT is not necessarily indicative of an increased risk of local recurrence. A low tumor shrinkage rate also was not predictive of recurrence.

Gamma knife radiosurgery of craniopharyngioma: results of 30 cases treated at Nagoya Radiosurgery Center.

Evaluation of 30 cases of craniopharyngioma treated by Gamma Knife at Nagoya Radiosurgery Center (NRC), Nagoya Kyoritsu Hospital since July, 2004 has been made. The mean volume of the tumor was 2.64 ml, which was treated with the marginal dose of 11.7 Gy. Mean follow-up period was 79.9 months. The effects were evaluated by MRI findings, neuro-endocrine and hypothalamic signs and symptoms, complications and KPS every 3~6 months. As the results, complete remission was obtained in 8, partial remission in 12, no change in 6, progression in 3, in which two died by hypothalamic invasion. Tumor response rate was 68.9% and control rate 87.9%. Actuarial survival was 96% at 5 and 86% at 10 years. However, progression free survival was 76% and 76%, respectively. Using marginal dose of 11.7Gy to a smaller tumor, better control without complications has been obtained. KPS was excellent in 14, good in 9, fair in 2, poor in 1 and unknown in a case. Finally, there were three deaths, where two were died of tumor progression and one by infirmity. The progression of hypothalamic symptoms other than diabetes insipidus were found in two cases. Volume reduction and effective dose setting will be important for the improvement of QOL and survival after combined microsurgery and radiosurgery of craniopharyngioma.

Stereotactic body radiotherapy using a radiobiology-based regimen for stage I non-small-cell lung cancer: five-year mature results.

INTRODUCTION: Although the protocol of 48 Gy in four fractions over 4 days has been most often employed in stereotactic body radiotherapy (SBRT) for stage I non-small-cell lung cancer in Japan, higher doses are necessary to control larger tumors, and interfraction intervals should be longer than 24 hours to take advantage of reoxygenation. We report the final results of our study testing the following regimen: for tumors less than 1.5, 1.5-3, and greater than 3 cm in diameter, 44, 48, and 52 Gy, respectively, were given in four fractions with interfraction intervals of greater than or equal to 3 days. METHODS: Among 180 histologically proven patients entered, 120 were medically inoperable and 60 were operable. The median patient age was 77 years (range, 29-89). SBRT was performed with 6-MV photons using four noncoplanar and three coplanar beams. Isocenter doses of 44, 48, and 52 Gy were given to four, 124, and 52 patients, respectively. RESULTS: The 5-year overall survival rate was 52.2% for all 180 patients and 66% for 60 operable patients. The 5-year local control rate was 86% for tumors less than or equal to 3 cm (44/48 Gy) and 73% for tumors greater than 3 cm (52 Gy; p = 0.076). Grade greater than or equal to 2 radiation pneumonitis developed in 13% (10% for the 44/48-Gy group and 21% for the 52-Gy group; p = 0.056). Other grade 2 toxicities were all less than 4%. CONCLUSIONS: Our first prospective SBRT study yielded reasonable local control and overall survival rates and acceptable toxicity. Refinement of the protocol including dose escalation may lead to better outcome.

Useful base plate to support the head during Leksell skull frame placement in gamma knife perfexion radiosurgery.

We developed an original base plate to support both the patient's head and a Leksell stereotactic skull frame during frame placement in the supine position. The base plate is made of transparent acrylic board with holes at the posterior posts for injection of local anesthetics and maneuver of fixation screws through them. A stable and comfortable position of the patient's head in a supine position is obtained and maintained on this base plate with an air-pressure cuff beneath the patient's head. The patient is able to keep a stable, relaxed and comfortable posture during the procedures of skull frame placement.

Gamma knife radiosurgery of brain metastasis from malignant pleural mesothelioma--report of three cases with autopsy study in a case.

The median survival time of malignant pleural mesothelioma (MPM) has been 9 months. Given the short survival, there have been only few cases in which brain metastases have been diagnosed and treated before death. Three cases of brain metastases treated by gamma knife radiosurgery (GKR) are reported. Case I showed a metastatic lesion in the right frontal lobe which was treated by GKR two years after diagnosis of MPM. The lesion markedly reduced and the symptoms were improved, But the patient died of progression of pleural tumor four months after GKR. A year and three months after the diagnosis, asymptomatic bifrontal lesions were treated with GKR. However, Case 2 died of abdominal mass a month after. Case 3 showed headache one and half year after the diagnosis. Three brain lesions were treated by GKR, which disappeared in 4 months. The patient died of new multiple brain metastases and periventricular dissemination seven months after. The autopsy revealed a MPM occupying the left pleural cavity. No neoplastic lesion was found in gamma knife-treated sites. The cause of death was the mass effect by new metastatic lesions. GKR was found effective also for the treatment of brain metastasis of MPM.

Effective usage of a clearance check to avoid a collision in Gamma Knife Perfexion radiosurgery with the Leksell skull frame.

Skull frame attachment is one of the most significant issues with Gamma Knife radiosurgery. Because of the potential for suffering by patients, careful control of the frame position is required to avoid circumstances such as collision between the frame or the patient's head and the collimator helmet, and inaccessible target coordinates. This study sought to develop a simulation method to find the appropriate frame location on the patient's head by retrospective analysis of treatment plans for brain metastasis cases. To validate the accuracy of the collision warning, we compared the collision distance calculated using Leksell GammaPlan (LGP) with actual measured distances. We then investigated isocenter coordinates in near-collision cases using data from 844 previously treated patients and created a clearance map by superimposing them on CT images for just the frame, post and stereotactic fiducial box. The differences in distance between the simulation in LGP and the measured values were <1.0 mm. In 177 patients, 213 lesions and 461 isocenters, there was a warning of one possible collision. The clearance map was helpful for simulating appropriate skull frame placement. The clearance simulation eliminates the psychological stress associated with potential collisions, and enables more comfortable treatment for the patient.

Validation of accuracy in image co-registration with computed tomography and magnetic resonance imaging in Gamma Knife radiosurgery.

The latest version of Leksell GammaPlan (LGP) is equipped with Digital Imaging and Communication in Medicine (DICOM) image-processing functions including image co-registration. Diagnostic magnetic resonance imaging (MRI) taken prior to Gamma Knife treatment is available for virtual treatment pre-planning. On the treatment day, actual dose planning is completed on stereotactic MRI or computed tomography (CT) (with a frame) after co-registration with the diagnostic MRI and in association with the virtual dose distributions. This study assesses the accuracy of image co-registration in a phantom study and evaluates its usefulness in clinical cases. Images of three kinds of phantoms and 11 patients are evaluated. In the phantom study, co-registration errors of the 3D coordinates were measured in overall stereotactic space and compared between stereotactic CT and diagnostic CT, stereotactic MRI and diagnostic MRI, stereotactic CT and diagnostic MRI, and stereotactic MRI and diagnostic MRI co-registered with stereotactic CT. In the clinical study, target contours were compared between stereotactic MRI and diagnostic MRI co-registered with stereotactic CT. The mean errors of coordinates between images were < 1 mm in all measurement areas in both the phantom and clinical patient studies. The co-registration function implemented in LGP has sufficient geometrical accuracy to assure appropriate dose planning in clinical use.

Effect of skull contours on dose calculations in Gamma Knife Perfexion stereotactic radiosurgery.

In treatment planning of Leksell Gamma Knife (LGK) radiosurgery, the skull geometry defined by generally dedicated scalar measurement has a crucial effect on dose calculation. The LGK Perfexion (PFX) unit is equipped with a cone-shaped collimator divided into eight sectors, and its configuration is entirely different from previous model C. Beam delivery on the PFX is made by a combination of eight sectors, but it is also mechanically available from one sector with the remaining seven blocked. Hence the treatment time using one sector is more likely to be affected by discrepancies in the skull shape than that of all sectors. In addition, the latest version (Ver. 10.1.1) of the treatment planning system Leksell GammaPlan (LGP) includes a new function to directly generate head surface contouring from computed tomography (CT) images in conjunction with the Leksell skull frame. This paper evaluates change of treatment time induced by different skull models. A simple simulation using a uniform skull radius of 80 mm and anthropomorphic phantom was implemented in LGP to find the trend between dose and skull measuring error. To evaluate the clinical effect, we performed an interobserver comparison of ruler measurement for 41 patients, and compared instrumental and CT-based contours for 23 patients. In the phantom simulation, treatment time errors were less than 2% when the difference was within 3 mm. In the clinical cases, the variability of treatment time induced by the differences in interobserver measurements was less than 0.91%, on average. Additionally the difference between measured and CT-based contours was good, with a difference of -0.16% ± 0.66% (mean ±1 standard deviation) on average and a maximum of 3.4%. Although the skull model created from CT images reduced the dosimetric uncertainty caused by different measurers, these results showed that even manual skull measurement could reproduce the skull shape close to that of a patient's head within an acceptable range.

Efficacy of magnetic resonance imaging at 3 T compared with 1.5 T in small pituitary tumors for stereotactic radiosurgery planning.

PURPOSE: The objective of this study was to determine the value of high-field magnetic resonance imaging and to clarify the characteristics of each image among three-dimensional gradient echo (3D-GRE), two-dimensional spin echo (2D-SE) and inversion recovery (2D-IR) sequences used as contrast-enhanced T1-weighted images for stereotactic irradiation treatment planning of sellar lesions. MATERIALS AND METHODS: Pulse sequences of 2D-SE and 3D-spoiled gradient recalled acquisition in the steady state (3D-SPGR) using GRE at 1.5 T and 2D-IR and 3D-fast SPGR (3D-FSPGR) at 3 T after injection of contrast material were acquired for 14 small pituitary tumors. As quantitative methods, signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were evaluated using a region-of-interest analysis. RESULTS: There was no significant difference in SNR between 1.5-T SPGR and 3-T FSPGR, while 3-T IR was superior to 1.5-T SE. The 2D-SE and -IR provided significantly better CNR than 3D-GRE between tumor and normal structures. CONCLUSIONS: Three Tesla was found to be superior to 1.5 T in distinguishing tumors from the normal sellar structure. Optimal dose planning will utilize each advantage of imaging; 3D-GRE allows high-resolution acquisition and 2D-SE and -IR can offer better tissue contrast.

Trigeminal neuralgia caused by nerve compression by dilated superior cerebellar artery associated with cerebellar arteriovenous malformation: case report.

Intracranial arteriovenous malformation (AVM) is a rare cause of trigeminal neuralgia (TGN). In this presented case, successful resolution of AVM-related TGN following embolization and gamma knife stereotactic radiosurgery (GKRS) was obtained. A patient suffered from TGN on the left side, which was thought to be caused by root entry zone compression by dilated superior cerebellar artery (SCA) associated with cerebellar AVM. The cerebellar vermis AVM was embolized in endovascular surgery. The AVM was reduced in size and TGN was partially relieved. The patient subsequently underwent GKRS for the residual nidus. TGN was completely resolved within one year and a half. GKRS following embolization of the nidus improved the flow-related dilation of the SCA and completely relieved TGN.

Gamma knife stereotactic radiosurgery for intracranial hemangiopericytoma.

BACKGROUND: Intracranial hemangiopericytoma (HPC) is a rare tumors that comprises under 1% of all primary brain tumors. This tumor is notable for its aggressive clinical behavior, such as a high rate of recurrence after surgical resection and proclivity for extracanial metastases. For the management of recurrent intracranial tumors, we applied Gamma Knife radiosurgery (GKRS) in cases in which the tumors were well-circumscribed and measured less than 3 centimeters in diameter. In this study, we evaluated the efficacy and role of GKRS in controlling recurrent HPC.Materials and Methods: Between April 2004 and July 2010, we treated seven patients with intracranial HPC using GKRS. All patients underwent surgical resection prior to GKRS. The mean age of the patients at the first GKRS was 43.4 (range, 29 to 68) years. At the first GKRS, six patients of seven patients had one tumor, and the remaining patient had four tumors. Therefore, a total of 10 tumors were detected at the first GKRS, all of which were treated. The median follow-up time was 52.1 months (range, 13 to 71 months). During follow-up, three of the seven patients underwent a total of 22 repeat GKRS procedures for newly developed tumors or 4 lesions with regrowth. Ultimately, a total of 32 GKRS procedures were performed in the seven patients. The mean radiosurgery target volume was 4.1 ml (range, 0.3-23.9ml), and the mean marginal dose was 16.5 Gy (range, 10-20). RESULTS: Five patients were alive at the end of the follow-up visit, without any serious neurological deficits. One patient presented with extracranial metastasis and died from cerebrospinal dissemination of the tumor 71 months after the first GKRS. Another patient died from colon cancer during follow-up. The 1-, 3-, and 5-year local tumor control rates were 100%, 92% and 69.7%, respectively. CONCLUSIONS: GKRS is an effective management option for patients with recurrent hemangiopericytoma.

Simulational study of a dosimetric comparison between a Gamma Knife treatment plan and an intensity-modulated radiotherapy plan for skull base tumors.

Fractionated stereotactic radiotherapy (SRT) is performed with a linear accelerator-based system such as Novalis. Recently, Gamma Knife Perfexion (PFX) featured the Extend system with relocatable fixation devices available for SRT. In this study, the dosimetric results of these two modalities were compared from the viewpoint of conformity, heterogeneity and gradient in target covering. A total of 14 patients with skull base tumors were treated with Novalis intensity-modulated (IM)-SRT. Treatment was planned on an iPlan workstation. Five- to seven-beam IM-SRT was performed in 14-18 fractions with a fraction dose of 2.5 or 3 Gy. With these patients' data, additional treatment planning was simulated using a GammaPlan workstation for PFX-SRT. Reference CT images with planning structure contour sets on iPlan, including the planning target volume (PTV, 1.1-102.2 ml) and organs at risk, were exported to GammaPlan in DICOM-RT format. Dosimetric results for Novalis IM-SRT and PFX-SRT were evaluated in the same prescription doses. The isocenter number of PFX was between 12 and 50 at the isodose contour of 50-60%. The PTV coverage was 95-99% for Novalis and 94-98% for PFX. The conformity index (CI) was 1.11-1.61 and 1.04-1.15, the homogeneity index (HI) was 1.1-3.62 and 2.3-3.25, and the gradient index (GI) was 3.72-7.97 and 2.54-3.39 for Novalis and PFX, respectively. PTV coverage by Novalis and PFX was almost equivalent. PFX was superior in CI and GI, and Novalis was better in HI. Better conformality would be achieved by PFX, when the homogeneity inside tumors is less important.

Therapeutic approach to chordoid glioma of the third ventricle.

Chordoid glioma of the third ventricle is considered to be a benign glial tumor located exclusively in the mid-anterior portion of the third ventricle near the hypothalamus and optic nerves, with the histological features of a chordoma and immuno-labeling for glial fibrillary acidic protein. Unfortunately, the clinical outcome of chordoid glioma has been poor, even in patients receiving gross total or partial removal with or without radiotherapy. Three cases of chordoid glioma of the third ventricle were treated with less invasive microsurgery for pathological diagnosis or partial removal without neuro-endocrinological complication, followed by gamma knife radiosurgery using a lower marginal dose for the optic nerves and hypothalamus. Gamma knife radiosurgery was performed after open biopsy in two patients, and after partial removal in the third patient using a lower marginal dose of 10.5 to 12 Gy. Serial magnetic resonance imaging revealed gradual decrease or at least no change in the tumor size, without significant complication at follow up 70 and 66 months later in two cases. The third patient accidentally died 13 months after gamma knife treatment. We conclude that low dose gamma knife radiosurgery after less invasive microsurgery is both safe and effective for the control of chordoid glioma of the third ventricle over a very long follow-up period.

Gamma knife stereotactic radiosurgery for atypical and malignant meningiomas.

BACKGROUND: Non-benign meningioma has a known trend to recur repeatedly. The results of Gamma Knife stereotactic radiosurgery (GKS) for recurrent or residual atypical and malignant meningiomas are reported. METHODS: Thirty patients (13 men, 17 women) with World Health Organization (WHO) grade II (24 cases) or grade III (6 cases) intracranial meningiomas underwent GKS. Their age varied from 30 to 86 years (mean 64 years). Before GKS, the tumor was surgically resected in all patients, and 11 of them also underwent conventional external beam radiation therapy, LINAC-based stereotactic radiotherapy (SRT), or intensity-modulated radiation therapy. FINDINGS: Of the 30 patients, 23 were followed after the initial GKS for a median period of 28 months (range 2-135 months). Local tumor control after treatment was 74 % at 1 year, 52 % at 2 years, and 34 % at 3 years. A total of 15 patients underwent repeat GKS (one to nine times) because of local or distant intracranial tumor progression, seven were subjected to surgical re-resection of the neoplasm, and four had additional SRT. At the time of the last follow-up, 21 patients were alive, and 2 had died. One of the latter expired because of brain tumor progression at 91 months after the initial GKS, and the other patient died from lung cancer. CONCLUSIONS: Although atypical and malignant meningiomas have a trend to recur repeatedly, aggressive tumor management with repeat GKS at the time of progression can provide long survival in these patients.

Early response and local control of stage I non-small-cell lung cancer after stereotactic radiotherapy: difference by histology.

To investigate the possible influences of various factors on tumor response to radiation, regression speeds and long-term local control rates of primary adenocarcinoma and squamous cell carcinoma of the lung after stereotactic body radiotherapy were evaluated. Ninety-one patients (65 men and 26 women) with a median age of 76 years were serially examined using computed tomography at 2, 4 and 6 months after treatment. Tumor histology was adenocarcinoma in 62 patients and squamous cell carcinoma in 29 patients. The prescribed dose was 48 Gy in four fractions given twice a week for T1 tumors (≤ 3 cm) and 52 Gy in four fractions given twice a week for T2 tumors (3-5 cm). Tumor shrinkage speed and 3-year local control rates were similar between T1 and T2 tumors and between patients with normal pulmonary function and those with impaired function. Squamous cell carcinomas shrank faster than adenocarcinomas at 2 and 4 months after radiation, but mean relative tumor size at 6 months and local control rates at 3 years did not differ significantly between the two histologies. Tumors in patients with a higher hemoglobin level tended to shrink faster but the control rates were not different. It is concluded that, although squamous cell carcinoma shrinks faster than adenocarcinoma, the two types of lung cancer are of similar radiosensitivity in terms of long-term control rates. Radiosensitivity should not be evaluated by early tumor response.