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The Journal of the Korean Society for Therapeutic Radiology and Oncology 2000;18(2): 92-100. |
| Failure Pattern of Pineal and Ectopic Pineal Germ Cell Tumor after Gamma Knife Radiosurgery |
| Heung Lae Cho, Seung Chang Sohn |
| Department of Radiation Oncology Inje University, College of Medicine, Pusan, Korea. |
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| ABSTRACT |
PURPOSE:
This study was performed to determine the optimal treatment volume of patients treating with radiation therapy for intracranial germ cell tumor.
MATERIALS AND METHODS:
From 1993 to 1998, 19 patients with intracranial germ cell tumors treated by gamma knife radiosurgery were analyzed. The location of tumor was as follows; 9 cases on pineal region, 1 case on suprasellar region, and 9 cases of multiple lesion. 7 patients were pathologically verified; 5 cases of germ cell tumor and 2 cases of non germinomatous germ cell tumor. Tumor volume was ranged from 2.4 cm3 to 74 cm3. Irradiation dose was 10 Gy to 20 Gy with 50% isodose curve. Follow up period was 10 months to 54 months.
RESULTS:
Recurrences were observed in 14 cases among 19 (74%) patients. Complete remission and partial remission were achieved in 2 (11%) and 10 (53%) respectively. No response was observed in 7 (36 %). 2 cases were recurred within original tumor bed. 6 cases were recurred beyond but contiguous with tumor bed. Ventricular relapses separated from pretreatment tumor bed were 3. Spinal recurrences were 4. Among 8 recurred cases of which tumor volume is smaller than 20 cm3, 2 were recurred within original tumor bed, 4 were recurred beyond but contiguous with tumor bed, and 1 spinal recurrence. Meanwhile, 6 cases of which tumor volume larger than 20 cm3, 1 case was recurred beyond but contiguous with tumor bed, 2 ventricular recurrences separated with original tumor bed, and 3 spinal recurrences.
5 cases which did not show any recurrence sign showed characteristics of single lesion, tumor volume smaller than 20 cm3 and normal tumor marker. All of 4 cases of spinal recurrences happened in the case having ventricular invasion or lesion. Among 9 cases having multiple lesion, only 3 cases recurred within original tumor bed or around tumor bed, the other 6 cases recurred separated from pretreatment tumor bed.
CONCLUSION:
Gamma knife radiosurgery is not recommended for the treatment of intracranial germ cell tumor. It is because of small treatment volume and inadequate radiation dose that are characteristics of gamma knife radiosurgery. Tumor volume, ventricular invasion or ventricular lesion in multiple lesion are important factors to be considered for the wide field radiation therapy. Tumor volume smaller than 20 cm3, single lesion, no ventricular lesion or invasion, and normal tumor marker are ideal indications for small involved field radiation therapy. Prophylactic spinal irradiation seems to be necessary when there is ventricular lesion, ventricular invasion, and multiple lesions. When the tumor volume is larger than 20 cm3, multiple lesions, abnormal tumor marker, and whole ventricular irradiation or partial brain irradiation would be possible and neoadjuvant chemotherapy would be most beneficial in these group. |
| Key Words:
Germ cell tumor, Intracranial, Failure pattern, Radiosurgery, Gamma knife |
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