Stereotaxic intracavitary irradiation for cystic craniopharyngiomas

Abstract

Stereotaxic intracavitary irradiation with instillation of phosphorus-32 (32P) colloidal chromic phosphate was performed in nine patients with cystic craniopharyngiomas. Serial neurological, ophthalmological, neuroendocrinological, and radiological examinations were performed before and after treatment. Dosimetry was determined based on a computerized tomography (CT) estimation of tumor volume, and was calculated to provide a tumoricidal dose (200 to 300 Gy) to the cyst wall. The follow-up period ranged from 14 to 45 months (mean 27 months). After treatment, all nine patients showed improvement of symptoms and radiological evidence of cyst regression. Because of an expanding solid component producing recurrent symptoms, one patient required a craniotomy 14 months after isotope instillation. Three of five patients with impaired visual acuity before surgery had significant improvement in acuity after treatment. Preoperative visual field defects in eight patients improved in four after 32P therapy. Of seven patients with preoperative endocrine abnormalities, one individual showed almost complete normalization and another had improvement in endocrine function. Patients who exhibited residual neuroendocrine function before isotope instillation developed no significant deterioration in endocrine status during the follow-up period. The findings suggest that stereotaxic intracavitary irradiation is a safe and effective treatment which should be considered as the initial surgery for cystic craniopharyngiomas.

Surgical management of giant pediatric craniopharyngiomas

“…Others advocate intracavitary treatments for cystic tumors including irradiation with beta-emitting radioisotopes (phophorus-32 or yttrium-90) 5,33,38,60,61,87,89 or administration of the chemotherapeutic agent bleomycin, an antineoplastic antibiotic that interrupts DNA synthesis. 32,37,54,82 Many reported series utilizing intracavitary therapies are made up of small numbers of patients and usually include small-to moderate-sized, monocystic tumors, not multicystic giant forms.…”

“…32,37,70,82 Intracavitary therapies could prove ineffective for multicystic giant craniopharyngiomas and do not preclude subsequent de novo cyst formation or treat the solid portion of the tumor. 60,61,70 Some authors have demonstrated the ability of intracavitary therapy to decease mass effect via shrinkage or drainage of the cystic portion of the tumor and delay the need for RT in children.…”

Efficacy of phosphorus-32 brachytherapy without external-beam radiation for long-term tumor control in patients with craniopharyngioma

“…19 A number of studies have assessed this modality since then. 4,5,7,11,17,21,22,27,28 By and large, these studies have shown good cyst control with 1 or more instillations of P32 or yttrium-90. Almost all of these studies (including one from our institution) included patients who underwent multiple modalities of therapy, including varying degrees of resection and EBR.…”

“…Patients in this study did undergo EBR therapy prior to or concomitant with intracystic therapy. Pollack et al 21 published an early experience with P32 instillation in 9 patients. Their study showed significant reduction in cyst size on follow-up imaging in all patients.…”

“…Numerous studies have been published on its techniques, indications, and efficacy. 4,5,7,11,12,17,21,[26][27][28] In most studies, brachytherapy is combined with EBR. Previously, we attempted to treat predominantly cystic craniopharyngiomas with brachytherapy alone, withholding external radiation.…”