Metastases to the spinal epidural space with compression of the spinal cord or cauda equina are commonly encountered by physicians in a variety of clinical field. In the recent past, decompressive laminectomy followed by radiotheray was thought to be the best available treatment. More recently, radiotherapy alone has been advocated as an alternative treatment mode with a similar rate of effectiveness. This study compares laminectomy followed by radiotherapy to radiotherapy alone in the treatment of spinal epidural metastases in a randomized, prospective clinical trial. No significant difference was found in the effectiveness of the two treatment methods in regard to pain relief, improved ambulation, or improved sphincter function. Patients with an incomplete myelographic block fared well regardless of treatment, and those with a complete block fared poorly. Because of the limited size of this study and because of certain unforeseen design defects, the results are suggestive but not conclusive. Suggestions are made for a future randomized, prospective multicenter study that would conclusively answer the perplexing question as to the most efficacious method for treating spinal epidural metastases.

Of 34 evaluated patients with primary spinal cord tumors, 32 were irradiated at our institutions between 1969 and 1983. The results are reported of 32 patients, 16 with ependymoma and 16 with astrocytoma, who were treated with postoperative external beam radiotherapy following biopsy or subtotal resection. Twenty-nine patients received 45-55 Gy megavoltage beam irradiation in five to six weeks, and the remaining three patients received less than 40 Gy. The minimum follow-up was five years. Five- and ten-year actuarial survival rates for the entire group of patients were 73% (22/30) and 50% (8/16), respectively, including three patients who were salvaged by surgery after radiotherapy failures. Corresponding five- and ten-year relapse-free survival rates were 60% (18/30) and 32% (6/19), respectively. Of the 29 patients who received more than 45 Gy, relapse-free survival at five years was 63% (17/27). Treatment failed in 13 patients, and all of those failures were within the irradiated portals. Patients with ependymomas have significantly better relapse free survival than those with astrocytomas, 80% vs. 40% (p less than 0.05). There was a significant difference in survival between patients with tumors involving the cervical spine and those with tumors in the other locations, 45% vs. 89% (p less than 0.05). There was no significant difference in survival between patients with cauda equina tumors and those with tumors of the spinal cord, 100% vs. 68% (p less than 0.05). No radiotherapy-related neurological deficit was noted with a maximum 20 year follow-up. This study confirms that external beam radiotherapy is a safe and effective treatment modality for primary spinal cord tumors.

We assessed a treatment plan of local therapy (resection and placement of permanent low dose-rate I-125 seeds) without whole brain irradiation in 15 patients with solitary brain metastasis (SBM) from primary non-small cell lung cancer between January, 1991 and May, 1996. Thirteen lesions were confirmed as solitary by MRI scan, and 2 patients had CT scan only. With median follow up of 14 months, 3 patients remain alive at 6, 33, and 62 months post-resection. Median survival is 14 months for all patients and 26 months for patients with SBM as the only site of disease. Five tumors failed in the brain: 2 solitary recurrences adjacent to the site of SBM, 2 multiple metastases outside the primary site, and 1 multiple recurrence including the primary site. No failures were seen with SBM <2.5 cm. Only 2 of 13 patients with SBM confirmed with MRI experienced relapses elsewhere in the brain. Recurrence rates both adjacent and outside the area of the initial brain lesion are similar to studies employing resection plus whole brain irradiation (WBI), and the patient is spared the acute and potential late toxicity of WBI. This approach may be considered for selected patients with solitary brain metastases (SBMs), although further experience with larger patient numbers is needed.

Optimal management of symptomatic cavernous angiomas (CA) located in the thalamus and the brainstem is problematic. Clinical and radiological (MRI) follow-up series suggest that having hemorrhaged once, recurrent hemorrhage with progressive neurologic dysfunction may commonly occur. We have therefore chosen to treat these lesions when first symptomatic with stereotactic linear radiosurgery (SLR). We now report, after a median follow-up of 27 months, 12 patients with CAs (9 women, 3 men, mean age 40 years) treated in this fashion. Ten patients presented with hemorrhage (3 had more than one hemorrhage): two patients had new onset seizures. All patients had enhanced MRI/MRAs characteristic of CA. There were five brainstem and five thalamic CAs, and one each in the temporal lobe and insula. Cerebral angiograms were done in 8 patients for comparison with their respective MRAs. Only one CA was visualized in the late venous phase on cerebral angiogram and identical vascular features were appreciated on the MRA. The diameter of the CAs ranged from 1.0 to 3.0 cm with a mean of 1.6 cm. Dosimetry planning was based on MRI/CT features and the mean dose at the isocenter was 2.167 cGy (range = 2,000–2,500 cGy) delivered with a mean collimation diameter of 1.46 cm (range = 1.0–2.0 cm). All 12 patients continued to improve neurologically after SLR and had MRI-documented changes in their lesions: in general, the lesions became smaller and signal characteristics converted to methe-maglobin. However, 1 patient had an early post-SLR hemorrhage, documented by MRI, at 4.5 months. This patient''s lateral mesencephalic syndrome subsequently resolved and he was functionally improved, compared with baseline, at 22 months. Two patients developed hemiparesis at 7 and 9 months following SLR. One patient had a large pontine CA (2.0 cm) and the other a small peduncle CA (1.1 cm). Both patients had delayed brainstem radiation injury without rebleed documented on Gd-DTPA MRI. Three additional patients underwent SLR safety but have been followed less than 6 months each. Our experience suggests that radiosurgery for cavernous angioma protects against rebleed (though, as expected, not early rebleeds) as a recent study indicated a median of 12 months to recurrent hemorrhage. Delayed radiation injury may occur more frequently than expected from conventional dosimetry when this technique is used deep within the brain. We now target the lesion margins more conservatively by excluding the surrounding hemosiderin-stained parenchyma.

A computer-controlled adaptive phased array radiofrequency hyperthermia system for improved therapeutic tumor heating is experimentally investigated. Adaptive array feedback techniques are used to modify the electric-field in hyperthermia experiments with a homogeneous saline phantom target. A hyperthermia phased-array antenna system has been modified to implement adaptive nulling and adaptive focusing algorithms. The hyperthermia system is a ring phased-array antenna applicator with four independently controlled RF transmitter channels operating at a CW frequency of 100 MHz. The hyperthermia phased array is made adaptive by software modifications which invoke a gradient-search feedback algorithm that controls the amplitude and phase of each transmitter channel. The gradient-search algorithm implements the method of steepest descent for adaptive nulling (power minimization) and the method of steepest ascent for adaptive focusing (power maximization). The feedback signals are measured by electric-field short-dipole probe antennas. The measured data indicate that with an adaptive hyperthermia array it may be possible to maximize the applied electric field at a tumor position in a complex scattering target body and simultaneously minimize or reduce the electric field at target positions where undesired high-temperature regions (hot spots) occur.