Stereotactic Intracavitary Irradiation Research Articles

Stereotactic Intracavitary Irradiation for Cystic Craniopharyngiomas with Rhenium-186

Abstract Objective The intracavitary irradiation of cystic tumors has been used as a therapeutic alternative modality in the management of cystic craniopharyngiomas. In the present study, we review our experience, considering the technical issues, outcomes, and complications associated with the use of stereotactic intracavitary irradiation (SICI) with colloidal rhenium-186 (186Re) for cystic craniopharyngioma. Material and Methods The records of 33 patients with cystic craniopharyngiomas treated by SICI with colloidal 186Re were retrospectively reviewed. The median radiation dose to the cyst wall was of 408 Gy (range: 175 Gy to 500 Gy). All tumors were composed of a large cyst cavity, and 9 (27.3%) also had a solid component. The mean follow-up period was of 3.7 years. Results After SICI, 31 (93.9%) patients showed radiological evidence of cyst regression, and, in 2 (6.1%), no response was observed. An improvement in the visual deficits was observed in 8 cases (24.2%), and an improvement in endocrinogical disturbances, in 2 cases (6.1%). We observed complications in 3 patients (9.1%): diabetes insupidus in 1 case (3%), aggravation of visual acuity in 1 case (3%), and severe headache after infusion of the colloid in 1 case (3%); and 1 patient (3%) died after meningitis. Conclusion Stereotactic intracavitary irradiation with colloidal 186Re is a safe procedure, with satisfactory results in the present series, and should be considered, in the management of cystic craniopharyngiomas, the first-intention therapy or as an adjuvant to other therapeutical modalities, with acceptable morbidity and mortality rates.

OR2804 Endocrine And Vision Outcomes Following 90Yttrium Therapy For Cystic Sellar Lesions—A Prospective Cohort Study

Abstract Disclosure: M.A. MacLean: None. S. Ahmad: None. A.L. Hebb: None. A. Tahir: None. R. Greene: None. D.B. Clarke: None. S.A. Imran: None. Background: Untreated cystic sellar lesions can cause vision loss, endocrine dysfunction, and obstructive hydrocephalus related to growth and mass effect. Microsurgical resection, stereotactic aspiration, and radiation treatment strategies are limited by significant complications and high risk of recurrence. Stereotactic intracavitary irradiation with the beta-emitting isotope 90Yttrium (90Yt) has been proposed as an alternative to mitigate these challenges. Long term-efficacy data is lacking. Here, our objective was to prospectively assess the effect of 90Yt on cyst volume, endocrine, and vision outcomes. Methods: We conducted a Health Canada approved, single-centre, prospective cohort study. Clinical outcome measures included cyst volume measured on magnetic resonance imaging, formal visual field (VF) testing, and hypothalamic-pituitary (HP) hormonal function. All patients provided informed consent and underwent right frontal stereotactic insertion of 90Yt colloid (200 Gy cyst wall). Results: Twenty-two patients (55% females) received 90Yt therapy. Mean age was 63.5 (SD 15.4) years with no difference between genders (p = 0.055). Mean duration of follow-up was 52 months (range 5-113). Cystic lesions included: craniopharyngioma (86%), Rathke’s cleft cyst (9%) and cystic prolactinoma (5%). Mean tumor cyst volumes were reduced by 77% at 12-month follow-up (pre-operative: 5.2, SD 4.5 cc; 12 months post-operative: 1.2, SD 1.5 cc; p = 0.002). Males had larger tumor volumes at baseline (7.7, SD 5.0 cc vs. 3.2, SD 2.8; p = 0.02) and 3 months (4.7, SD 3.4 vs. 1.8, SD 2.0; p = 0.04) but these differences had resolved by 9-month follow-up. Pre-operative clinical features included: VF deficit (36%), VF deficit plus headache (36%), headache alone (9%), hydrocephalus (5%), and 14% were asymptomatic. HP hormone dysfunction was observed in 59% of patients pre-operatively (27% complete; 73% partial) and 68% post-operatively (p = 0.50); specifically, no differences were found pre- and post-operatively for secondary hypogonadism (50% vs. 55%), hypothyroidism (45% vs. 59%), hypoadrenalism (36% vs. 27%), growth hormone deficiency (27% vs. 23%), diabetes insipidus (23% vs. 27%), and hyperprolactinemia (36% vs. 36%) (all p > 0.05). Pre-operative VF deficits were found in 68% of patients, of which 32% normalized and 36% remained stable (p = 0.180). Worsened vision was detected in 9% of patients post-operatively. Treatment failure requiring conventional surgery occurred in 18% of patients. Conclusions:90Yt therapy significantly reduced tumor cyst size and stabilized both endocrine function and vision in patients with cystic lesions of the sellar region. Presentation: Sunday, June 18, 2023

P.107 Endocrine and vision outcomes following 90Yttrium therapy for cystic sellar lesions: a prospective cohort study

Background: Due to high risk of recurrence and complications associated with microsurgical resection or aspiration of enlarging cystic sellar lesions, stereotactic intracavitary irradiation with 90Yttrium (90Yt) has been proposed as an alternative to mitigate these challenges. Long-term efficacy data for this procedure is lacking. Methods: We conducted a Health Canada approved, single-centre, prospective cohort study to assess the effect of 90Yt therapy on cyst volume, visual field (VF) testing and endocrine function. All patients underwent right frontal stereotactic insertion of 90Yt colloid (200 Gy cyst wall). Results: 22 patients [mean age = 63.5 (± 15.4) years] received 90Yt therapy. Mean follow-up was 52 (5-113) months. Cysts included: craniopharyngioma (86%), Rathke’s cleft cyst (9%) and cystic prolactinoma (5%). Mean cyst volume reduction was 77% at 12-months (5.2 ± 4.5 cc to 1.2 ± 1.5 cc; p = 0.002). Rate of pre- and post-op hormonal dysfunction was 59% and 68%, respectively (p = 0.50). Pre-operative VF deficits were found in 68% of patients, of which 32% normalized and 36% remained stable (p = 0.180). Worsened vision was detected in 9% of patients post-operatively. Conclusions: 90Yttrium therapy significantly reduces sellar cyst size without having a deleterious effect on vision and endocrine function.

Management of cystic craniopharyngiomas with intracavitary irradiation with 32P.

Cystic craniopharyngiomas are the most frequent intracranial neoplasm of nonglial origin in children. Follow-up data were analyzed to assess the value of intracavitary irradiation with stereotactically applied 32P radioisotopes for the treatment of patients with craniopharyngioma cysts admitted to Shohada Tajrish Hospital, Tehran, Iran, between 1998 and 2005. Patients with predominantly cystic craniopharyngiomas, who underwent stereotactic intracavitary irradiation, were followed for tumor response and complications. Beta-emitting 32P isotopes were injected into cysts using a computed tomography-guided and computer-assisted three-dimensional stereotactic treatment planning and application system. The cumulative dose to the inner surface of the cyst wall was 250 Gy. Twenty-two (12 females and 10 males) patients with a mean+/-SD age of 14.0+/-6.6 (range: six to 35) years were studied. The tumor response rate gained with 32P-labeled chromic phosphate was 73% (16 of 22 cysts). The mean+/-SD survival after intracavitary irradiation was 25.4+/-6.8 (95% CI: 12.0 - 38.7) months. Intracavitary irradiation using 32P is highly effective in the treatment of cystic craniopharyngiomas. In patients with solitary cyst treated exclusively with this method, it has been the only necessary therapy over a long period. It seems reasonable to recommend intracavitary irradiation as the initial treatment for selected patients and as palliative therapy in those with recurrence.

Management of cystic craniopharyngiomas with phosphorus-32 intracavitary irradiation.

The efficacy of stereotactic intracavitary irradiation with phosphorus-32 ((32)P) for patients with cystic craniopharyngiomas was assessed on the basis of patient survival, tumor control, and visual and endocrinological function before and after treatment. Limited data are available regarding long-term outcomes. Forty-nine patients were treated with stereotactic (32)P intracavitary irradiation. Of these, 25 had had no prior treatment as the primary treatment, and 24 were treated for residual or recurrent tumor cysts. At the time of (32)P intracavitary irradiation, 34 of the patients were adults, and 15 were children younger than 16 years of age. The mean cyst volume was 13 ml. The radiation dose varied from 189 to 250 Gy to the cyst wall during five half-lives of the isotope (mean, 224 Gy). The mean follow-up periods were 7 years after diagnosis and 4 years after (32)P treatment. The actuarial survival rates were 90% at 5 years after the diagnosis and 80% at 10 years. The actuarial tumor cyst control rates were 76% at 5 years and 70% at 10 years after the diagnosis. After treatment, 9 (23%) of 40 patients who underwent preoperative and postoperative visual testing were found to have delayed worsening in visual function, 6 as a result of tumor progression and 3 attributed to irradiation. Nineteen patients (48%) had improved visual function. Of 17 patients who had normal preoperative pituitary function or stalk effect, 12 (71%) had preserved and 5 (29%) had worsened visual function. No complications other than visual or endocrinological deterioration occurred in these patients. For patients with cystic craniopharyngiomas, (32)P intracavitary irradiation proved effective, with a low risk of complications, for the control of tumor cysts but not of solid tumor components.

The role of stereotactic radiosurgery for low-grade astrocytomas

This study was conducted to examine the role of radiosurgery in the management of patients with recurrent or unresectable low-grade astrocytomas. During a 13-year interval, 49 patients underwent stereotactic radiosurgery as part of multimodal treatment of their recurrent or unresectable low-grade astrocytomas. Thirty-seven of these patients (median age 14 years) harbored pilocytic astrocytomas and 12 patients harbored World Health Organization (WHO) Grade II fibrillary astrocytomas (median age 25 years). Tumors involved the brainstem in 22 cases, cerebellum in four, thalamus in six, temporal lobe in five, frontal lobe in four, and parietal lobe in three, as well as the hypothalamus, corpus callosum, insular cortex, optic tract, and third ventricle in one patient each. Each diagnosis was confirmed with the aid of stereotactic biopsy sampling in 17 patients, open biopsy sampling in five, partial resection in 13, and near-total resection in 14. Multimodal treatment included fractionated radiotherapy in 14 patients, stereotactic intracavitary irradiation in five, chemotherapy in two, cyst drainage in eight, ventriculoperitoneal shunt placement in five, and additional cytoreductive surgery in five. Tumor volumes ranged from 0.42 to 45.1 cm3. The median radiosurgical dose to the tumor margin was 15 Gy (range 9.6-22.5 Gy). After radiosurgery, serial neuroimaging demonstrated complete tumor resolution in 11 patients, reduced tumor volume in 12, stable tumor volume in 10, and delayed tumor progression in 16. No procedure-related death was encountered. Forty-five of 49 patients are alive at a median follow-up period of 32 months after radiosurgery and 63 months after diagnosis. Sixteen patients participated in follow-up review for more than 60 months. Three patients died of local tumor progression. Stereotactic radiosurgery is a potential alternative or adjunctive intervention in the management of selected patients with pilocytic or WHO Grade II fibrillary astrocytomas, usually performed for small-volume tumors in an attempt to avoid larger-field fractionated radiotherapy.

Stereotactic Radiosurgery for Well-Circumscribed Fibrillary Grade II Astrocytomas: An Initial Experience

Objective: To examine the role of stereotactic radiosurgery in the management of patients with progressive, well-circumscribed grade II fibrillary astrocytomas. Methods: During a 13-year interval, 12 patients (median age: 25 years) required multimodality management for recurrent or unresectable World Health Organization (WHO) grade II fibrillary astrocytomas. Tumors involved the brainstem (n = 4), thalamus (n = 1), cerebellum (n = 1), frontal lobe (n = 4), temporal lobe (n = 1), and parietal lobe (n = 1). Diagnosis was confirmed by stereotactic biopsy (n = 5), partial resection (n = 5), and near total resection (n = 2). Multimodality management of patients prior to radiosurgery included fractionated radiation therapy (n = 4), stereotactic cyst drainage (n = 1), and ventriculoperitoneal shunt placement (n = 2). Tumor volumes varied from 1.2 to 45.1 cm³. The median radiosurgical dose to the tumor margin was 16 Gy. Results: After radiosurgery, serial imaging showed complete tumor resolution in 1 patient, reduced tumor volume in 4, stable tumor volume in 3, and delayed tumor progression in 4 (3 patients with increase in cyst size only). Therapy after radiosurgery included additional cytoreductive surgery (n = 1) for recurrence of a higher grade tumor, stereotactic cyst aspiration (n = 1), and stereotactic intracavitary irradiation (n = 1). All patients were alive at a median follow-up of 52 months after radiosurgery and 103 months after diagnosis. In 8 patients, follow-up lasted more than 60 months. Conclusion: Stereotactic radiosurgery is a potential alternative or adjunctive strategy in the management of selected patients with WHO grade II fibrillary astrocytomas.

Stereotactic radiosurgery for pilocytic astrocytomas when multimodal therapy is necessary.

The goal of this study was to examine the role of stereotactic radiosurgery in the treatment of patients with recurrent or unresectable pilocytic astrocytomas. During a 13-year interval, 37 patients (median age 14 years) required multimodal treatment of recurrent or unresectable pilocytic astrocytomas. Tumors involved the brainstem in 18 patients, cerebellum in three, thalamus in five, temporal lobe in four, and parietal lobe in two, as well as the hypothalamus, optic tract, corpus callosum, insular cortex, and third ventricle in one patient each. Diagnosis was confirmed with the aid of stereotactic biopsy in 12 patients, open biopsy in five, partial resection in eight, and near-total resection in 12. Multimodal treatment included fractionated radiation therapy in 10 patients, stereotactic intracavitary irradiation of tumor in four, chemotherapy in two, cyst drainage in six, ventriculoperitoneal shunt placement in three, and additional cytoreductive surgery in four. Tumor volumes varied from 0.42 to 25 cm3. The median radiosurgical dose to the tumor margin was 15 Gy (range 9.6-22.5 Gy). After radiosurgery, serial imaging demonstrated complete tumor resolution in 10 patients, reduced tumor volume in eight, stable tumor volume in seven, and delayed tumor progression in 12. No procedure-related death was encountered. Thirty-three (89%) of 37 patients are alive at a median follow-up period of 28 months after radiosurgery and 59 months after diagnosis. Eight patients participated in follow-up review for more than 60 months. Three patients died of local tumor progression. Stereotactic radiosurgery is a valuable adjunctive strategy in the management of recurrent or unresectable pilocytic astrocytomas. Despite the favorable histological characteristics and prognosis usually associated with this neoplasm, an adverse location, recurrence, or progression of this disease requires alternative therapeutic approaches such as radiosurgery.

Stereotactic intracavitary irradiation of large cystic craniopharyngiomas

During the years 1988–1992, 50 patients with large cystic craniopharyngioma were treated with stereotactic injection of radionuclide. The patients aged from 3 to 69 (average 21) years. Of these patients, 36 were primary cases and 14 were recurrences after previous major surgery. The cyst volume of craniopharyngiomas was 28–126 cm 3 (average 38 cm 3). The Leksell stereotactic system was used for injection of radionuclides Au-198, P-32 and Y90. Eighty-four injections were performed in 50 patients; additional injections took place at intervals of 1–6 months. There were no operative deaths and no serious complications. The follow-up period ranged from 1 to 5 years (average 2.6 years). Eighty-six percent of patients improved clinically and computed tomography re-examination confirmed shrinkage of the cysts.

The Role of Stereotactic Techniques in the Management of Craniopharyngiomas

Despite the advances of microsurgery, endocrinology, radiation therapy, and neuroimaging over the last half-century, craniopharyngiomas continue to present neurosurgeons with a therapeutic dilemma. The tumor's histologic benignity belies its aggressive biologic behavior. Although total resection is theoretically curative, the cost in terms of functional disability can be high, especially in light of reports describing long-delayed tumor recurrences ("false cure"). As in other intracranial neoplasms, multimodality therapy is often necessary over the course of a patient's lifetime. Stereotactic techniques (intracystic irradiation, radiosurgery, cyst aspiration, biopsy) have a well-established role in selected cases. To maximize preservation of neurologic, visual, and hypothalamic-pituitary functions, the application of stereotactic, microsurgical, or external irradiation techniques in an individual patient must take into account all of the patient's prior treatments as well as the current status of his or her tumor. Our current recommendation for multimodality treatment of craniopharyngiomas is illustrated in Figure 5. Stereotactic surgery has a definitive role in the life-long management of some patients, and plays an important adjunctive role in many others.

Stereotactic intracavitary irradiation of cystic neoplasms of the brain.

Ten patients with intracranial cystic tumors underwent stereotactic intracavitary irradiation using 32P colloidal chromic phosphate. Accurate dosimetry (25,000-30,000 rad to the cast wall) was achieved by volume estimation using computed tomography. Between 1 and 15 months after surgery both craniopharyngioma and astrocytoma cysts regressed. Neurological, visual, and endocrinological deficits either stabilized or improved. Intracavitary irradiation should be the primary method of treating solitary cystic tumors of the brain.