Impact of margin for target volume in low-dose involved field radiotherapy after induction chemotherapy for intracranial germinoma.
OBJECTIVE
We previously published a report stating that germinomas with elevated serum beta human chorionic gonadotropin (HCG-beta) had a poor relapse rate, but these findings have not been supported by a multi-institutional trial. The margin for initial gross tumor volume (GTV) before surgery and chemotherapy of the same materials was investigated by retrospective review.


METHODS
The 27 patients reported on in the previous paper were analyzed. The two-dimensional margin from the initial GTV to 90% of the prescribed dose of 24 Gy was 2.0 cm for a solitary lesion in the protocol. This margin was measured retrospectively without knowledge of the serum HCG-beta level. The whole ventricle field was used for patients with multifocal disease and whole central nervous system field was used for disseminated disease, respectively.


RESULTS
Six relapses were seen in 18 patients with solitary tumors, and were treated with the minimum margin of 1.5 cm or less to the initial GTV. Five of the 6 had initially elevated serum HCG-beta at the median of 7.4 mIU/mL, ranging from 0.7-233 mIU/mL. No relapses were seen in the 9 patients who were treated with whole ventricle or whole central nervous system field.


CONCLUSIONS
An inadequate margin and elevated serum HCG-beta were equally determined to be candidates that caused the poor local control. The whole ventricle is recommended as the smallest target volume for germinoma with or without elevated HCG-beta after induction chemotherapy.
Shirato
Hiroki
H
Departments of Radiology, Neurosurgery, and Pediatrics, Hokkaido University School of Medicine, North-15 West-7, Kita-ku, Sapporo 060-8638, Japan. hshirato@radi.med.hokudai.ac.jp
Aoyama
Hidefumi
H
Ikeda
Jun
J
Fujieda
Kenji
K
Kato
Norio
N
Ishi
Nobuaki
N
Miyasaka
Kazuo
K
Iwasaki
Yoshinobu
Y
Sawamura
Yutaka
Y
D000293:Adolescent; D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood; D001932:Brain Neoplasms / Q000097:blood / Q000188:drug therapy / Q000532:radiotherapy*; D002648:Child; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D003131:Combined Modality Therapy; D018237:Germinoma / Q000097:blood / Q000188:drug therapy / Q000532:radiotherapy*; D006801:Humans; D009364:Neoplasm Recurrence, Local; D012074:Remission Induction; D012189:Retrospective Studies
D014408:Biomarkers, Tumor; D018997:Chorionic Gonadotropin, beta Subunit, Human