BACKGROUND:The most common regimen of stereotactic body radiotherapy (SBRT) for stage I nonsmall cell lung cancer in Japan is 48 grays (Gy) in 4 fractions over 4 days. Radiobiologically, however, higher doses are necessary to control larger tumors, and interfraction intervals should be >24 hours to take advantage of reoxygenation. In this study, the authors tested the following regimen: For tumors that measured <1.5 cm, 1.5 to 3.0 cm, and >3.0 cm in greatest dimension, radiation doses of 44 Gy, 48 Gy, and 52 Gy, respectively, were given in 4 fractions with interfraction intervals of !3 days. METHODS: Among 180 patients with histologically proven disease who entered the study, 120 were medically inoperable, and 60 were operable. The median patient age was 77 years (range, 29-92 years). SBRT was performed with 6-megavolt photons using 4 noncoplanar beams and 3 coplanar beams. Isocenter doses of 44 Gy, 48 Gy, and 52 Gy were received by 4 patients, 124 patients, and 52 patients, respectively. RESULTS: The overall survival rate for all 180 patients was 69% at 3 years and 52% at 5 years. The 3-year survival rate was 74% for operable patients and 59% for medically inoperable patients (P ¼ .080). The 3-year local control rate was 86% for tumors 3 cm (44/48 Gy) and 73% for tumors >3 cm (52 Gy; P ¼ .050). Grade !2 radiation pneumonitis developed in 13% of patients (10% of the 44-Gy/48-Gy group and 21% of the 52-Gy group; P ¼ .056). All other grade 2 toxicities developed in <4% of patients. CONCLUSIONS: The SBRT protocol used in this study yielded reasonable local control and overall survival rates and acceptable toxicity. Dose escalation is being investigated.
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.
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.
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.
Skull base metastases are challenging situations because they often involve critical structures such as cranial nerves. We evaluated the role of stereotactic radiotherapy (SRT) which can give high doses to the tumors sparing normal structures. We treated 11 cases of skull base metastases from other visceral carcinomas. They had neurological symptoms due to cranial nerve involvement including optic nerve (3 patients), oculomotor (3), trigeminal (6), abducens (1), facial (4), acoustic (1), and lower cranial nerves (1). The interval between the onset of cranial nerve symptoms and Novalis SRT was 1 week to 7 months. Eleven tumors of 8-112 ml in volume were treated by Novalis SRT with 30-50 Gy in 10-14 fractions. The tumors were covered by 90-95% isodose. Imaging and clinical follow-up has been obtained in all 11 patients for 5-36 months after SRT. Seven patients among 11 died from primary carcinoma or other visceral metastases 9-36 months after Novalis SRT. All 11 metastatic tumors were locally controlled until the end of the follow-up time or patient death, though retreatment for re-growth was done in 1 patient. In 10 of 11 patients, cranial nerve deficits were improved completely or partially. In some patients, the cranial nerve symptoms were relieved even during the period of fractionated SRT. Novalis SRT is thought to be safe and effective treatment for skull base metastases with involvement of cranial nerves and it may improve cranial nerve symptoms quickly.
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