Stereotaxic irradiation-procedure of brain tumors and pituitary adenomas by means of radio-isotopes and its results.

Abstract

The techniques, results, and complications of stereotactic implantation of P/sup 32/, Co/sup 60/, Ta/sup 182/, Ir/sup 192/, and Au/sup 198/ in the brain of 196 patients for radiotherapy of intracranial tumors are described. A stereotactic instrument is described and illustrated which permits implantation of the radioisotopes to within 0.5 mm of the desired site. There was a clear relation between the length of survival and the kind of radioisotope applied, localization of the tumor, and amount of the tumor dosage. With glioblastomas, for instance, longest survival was noted in those with frontal localization, following Co/sup 60/ irradiation, and an average tumor dosage of 10000 to 13000 r showed best results. Similar results, with even longer survival periods, were achieved in other dedifferentiated gliomas, in which the combination of intraoperative Ta/sup 182/ or Ir/sup 192/ implantation with a postoperative interstitial Co/sup 60/ irradiation achieved the best results, in comparison with a combination of operation and x-ray therapy. The survival rate, which is nearly twice as high as in x-ray treatment, shows a significant relation to the average tumor dosage and tumor localization. The period of treatment was also shortened by 65-75% compared to the time required for fractionated x-ray therapy. Inmore » 68% of the stereotaxic hypophysis operations, according to the size of the tumor, a total activity of 25 to 55 mc of a macromolecular suspension of Au/sup 198/ was implanted which was adsorbed on small graphite particles (50 to 60 mu ). In the other cases small seeds of P/sup 32/ were placed in the tumor. The long-term results show that visual acuity had improved significantly following secondary stereotaxic irradiation, or remained unaltered without change, in comparison to those patients that had been treated by operation only. On the other hand, the percentage of unimproved and deteriorated cases is much higher in the operated group. The operative mortality with primary stereotaxic punctures was nil, whereas surgical operative mortality totaled 19%. The survival rates of 90.4% of the patients with secondary stereotaxic irradiation and 76.1% with primary stereotaxic irradiation, in compari-son with only 62% of patients with operation only, prove significantly that effectively implanted interstitial irradiation can prolong life. Among operative complications, damage to the neighboring structures was not caused by stereotaxic puncture, but was caused secondarily by radiation, above all by gamma radiation. In six of the patients, therefore, an open decompression operation was necessary. There were some general transitory reactions in the first days, especially headache and cerebrospinal fluid pressure increase among recurrent and long-term complications, in 11.5%, visual acuity grew worse and the visual field was narrowed after 0.3 to 3 yr. It was concluded that primary, and especially secondary stereotaxic irradiation of hypophysis adenomas is clearly superior to surgical operation as concerns operative mortality as well as survival rate and rate of recurrence. The rate of improvement of visual acuity was 26 to 44% higher and that of the visual field 17 to 29% higher than following surgical operation only. However, one problem not yet solved satisfactorily is the long-term radiation damage of the chiasma and optic nerve. Perhaps filling the basal cisterns with x-ray contrast medium by means of the target needle, before the placing of the isotopes, may be of help in preventing this. (BBB)« less