The aim of the study was to evaluate the effect of phosphorus-32 colloid ([(32)P]) intracavitary irradiation on the treatment of patients with cystic craniopharyngiomas.

Twenty patients with predominantly cystic craniopharyngiomas were admitted from 1981 to 2006. Eleven patients had [(32)P] intracavitary irradiation by stereotactic injection or Ommaya cyst instillation as the primary treatment, and the remaining nine had the same internal irradiation as an adjuvant treatment after tumor resection. A calculated irradiation dose of 400 approximately 500 Gy per once was delivered to the cyst wall.

The patients were followed up ranging from 36 to 336 months; no operative morbidity or mortality was found from [(32)P] intracavitary irradiation. Fourteen patients (70%) had tumor progression and required further two to four times intracavitary irradiation. All 20 cases achieved tumor shrinkage or stabilization with effective outcome 3-6 months after the last [(32)P] therapy. For patients with cystic craniopharyngioma, [(32)P] administration by stereotactic injection or Ommaya cyst instillation is a safe and helpful option, which could improve the life quality, prolong the life span, and enhance the survival rate of cystic craniopharyngioma patients.