Management of Cystic Craniopharyngiomas with Phosphorus-32 Intracavitary Irradiation

OBJECTIVE: The efficacy of stereotactic intracavitary irradiation with phosphorus-32 (³²P) 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. METHODS: Forty-nine patients were treated with stereotactic ³²P 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 ³²P 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 32p treatment. RESULTS: 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. CONCLUSION: For patients with cystic craniopharyngiomas, ³²P intracavitary irradiation proved effective, with a low risk of complications, for the control of tumor cysts but not of solid tumor components.