Drug distribution and clinical safety in treating cystic craniopharyngiomas using intracavitary radiotherapy with phosphorus-32 colloid

: The present study evaluated drug distribution and clinical safety in treating patients with cystic craniopharyngioma (CP) with intracavitary radiotherapy using phosphorus-32 (32P) colloid. In total, 40 patients who were recently diagnosed with primary or recurrent cystic CP were enrolled into the study. Patients underwent stereotactic intracavitary therapy and were administered 32P colloid and iopamidol-300 (1:1 dilution). Head computed tomography (CT) scans were performed 2 h after surgery in order to assess drug distribution and leakage. Results obtained from the ophthalmic examination (visual acuity, visual field and fundus), enhanced head magnetic resonance imaging and/or CT scans, blood analysis, coagulation tests, electrolyte tests, pituitary hormone level analysis, and hepatic and renal function tests were compared between the 0.5, 1, 1.5 and 2 mCi groups. The 32P colloid per minute radioactive count was quantitatively measured in urine and blood samples using a CAPRAC well-type NaI γ counter at 1, 3 and 7 days post-surgery. In total, 6, 2 and 1 case(s) from the 2, 1.5 and 1 mCi groups, respectively, demonstrated heterogeneous drug distribution and intracavitary cerebrospinal fluid leakage. Furthermore, out of 24 patients, no significant differences were identified in blood analysis, blood biochemical measurements and pituitary hormone levels prior to and 7 days after surgery. Blood 32P deposition returned to normal levels within 3 days after surgery, whereas urine deposition returned to normal within 7 days after surgery. Methods utilized in the present study were advantageous in terms of convenience, speed and low cost, therefore, these techniques are suitable for continuous monitoring of patient 32P colloid deposition.