Treatment of cystic craniopharyngiomas with yttrium-90 colloid solution.

Abstract

<jats:p>The authors analyzed long-term follow-up data to assess the value of intracavitary irradiation with stereotactically implanted beta-emitting radioisotope <jats:sup>90</jats:sup>Y-silicate colloid for the treatment of craniopharyngiomas. Fifty-seven craniopharyngiomas in 42 patients were selected for retrospective analysis. The yttrium-90 was implanted intracavitally, using computerized tomography-guided and three-dimensional stereotactic treatment planning. The cumulative dose aimed at the inner surface of the cyst wall was 300 Gy.</jats:p> <jats:p>An average of 75% shrinkage of the initial cyst volume was observed. In 18 cases the reduction was more than 91%, and the cyst disappeared totally in 11 cases.</jats:p> <jats:p>A 50% decrease in cyst volume was usually apparent between the 2nd and 4th months. A 70% decrease in cyst volume was seen by the 5th and 6th months and an 80% reduction by the 7th and 8th months. Cysts that were unchanged remained so throughout the observation period. The time course of volume reduction could be expressed mathematically by the formula of 0.73 X e<jats:sup>-0.62 X T</jats:sup> + 0.27, where “e” is the basic number of natural logarithm and “T” is the time expressed in months. Mean survival duration after intracavitary irradiation was 9.4 years.</jats:p> <jats:p>The shrinkage of the cyst was a consequence of fibrosis of the wall, as seen on histopathological examination. The neuroophthalmological prognosis was favorable only when the optic disc was normal or nearly normal at the time of the treatment. In the presence of preexisting optic atrophy, visual deterioration proved to be irreversible. The long-term results support the view that intracavitary<jats:sup>90</jats:sup>Y-irradiation is a noninvasive and very effective method of treatment for craniopharyngioma cysts. Because of the 1.1 mm half-life decay of beta irradiation, it cannot influence the solid part of the tumor; therefore, the best result can be expected in solitary cysts.</jats:p>

Stereotactic Intracavitary Irradiation for Cystic Craniopharyngiomas with Rhenium-186

“…Stereotactic intracavitary irradiation can be repeated if no response is initially obtained, or even in the case of recurrence of the cyst, as we have performed successfully in two patients, as well as Pollack et al 13 The response of the intracavitary irradiation or the cystic shrinkage may take some months, and becomes stable after one year, and unfortunately cannot be previously preview. 18,19 The possible complications of this technique can be related to the stereotactic procedure itself (what is uncommon) or to the radioisotope injection, and they include intracerebral hematoma after cyst puncture, 21 meningitis, 18,19 and necrotic hemorrhage. All of these complications have been observed in the treatement of craniopharyngiomas using 90 Y.…”

“…Sometimes it is difficult to calculate the exact dose due to factors such as the irregular shape of the cyst or multiple cavities, which complicate the estimation of the volume. 10 Stereotactic intracavitary irradiation has been used mostly for the treatment of cystic craniopharyngiomas, with satisfactory results, 10,[18][19][20] but reports of its use in cases of cystic gliomas are very limited in the literature.…”

“…Stereotactic intracavitary irradiation has been used mostly for the treatment of cystic craniopharyngiomas, with satisfactory results, 10 18 19 20 but reports of its use in cases of cystic gliomas are very limited in the literature.…”

“…Stereotactic intracavitary irradiation can be repeated if no response is initially obtained, or even in the case of recurrence of the cyst, as we have performed successfully in two patients, as well as Pollack et al 13 The response of the intracavitary irradiation or the cystic shrinkage may take some months, and becomes stable after one year, and unfortunately cannot be previously preview. 18 19…”

Management of craniopharyngiomas

“…In primary or recurrent cystic tumors, intracavitary surgical therapy can be done using stereotactic techniques and the installation of radioactive isotopes into the cyst cavity, or the installation of a chemotherapeutic agent Bleomycin 13 and currently alpha interferon INF α can be considered 4,19 . Yttrium-90 intracavitary irradiation may be used stereotactically applied (STAIR) in craniopharyngioma cysts, with a 50% decrease in cyst volume maybe apparent two or four months later, a 70% decrease in cyst volume between the 5th and 6th months and an 80% reduction by the 7th and 8th months 21 .…”