Hypofractionated radiotherapy boost for dose escalation as a treatment option for high-grade spinal cord astrocytic tumor.
OBJECTIVE
To retrospectively analyze the outcome of post-operative radiotherapy for spinal cord glioma with the emphasis on the hypofractionated radiotherapy boost for dose escalation as a treatment option for high-grade spinal cord astrocytic tumors.


METHODS
Forty-one patients with spinal cord glioma received post-operative radiotherapy between 1979 and 2003. The median age was 34 years (range, 10-66 years). Median follow-up was 49 months (range, 5-291 months). There were 12 low-grade astrocytic tumors, 11 high-grade astrocytic tumors, 16 low-grade ependymal tumors and 2 high-grade ependymal tumors. Among 11 patients with high-grade astrocytic tumors, 5 with anaplastic astrocytoma and 1 with glioblastoma received hypofractionated radiotherapy boost for dose escalation. The median total dose of the conventional radiotherapy was 45.5 Gy in 19 fractions (range, 30.0-60.0 Gy). The median normalized total dose (using daily dose of 2.0 Gy and an alpha/ per thousandbeta ratio of 2.0) of the hypofractionated radiotherapy boost was 131 Gy2 (range, 85-249).


RESULTS
The Kaplan-Meier survival rates at 10 years from the date of the first surgery were 64% for the entire group, 47% for the astrocytic tumors and 84% for the ependymal tumors, respectively (P=0.009). Among 11 patients with high-grade astrocytic tumors, the actuarial survival rate at 10 years was 35%. The actuarial survival rates at 10 years were 67% for those who received hypofractionated radiotherapy boost for dose escalation, and 20% for those who did not (P=0.47).


CONCLUSIONS
The results for ependymal tumors and low-grade astrocytic tumors were comparable to those reported in the literature. Hypofractionated radiotherapy boost for dose escalation may help to prolong the survival of patients with high-grade astrocytic tumors.
Katoh
Norio
N
Department of Radiology, Hokkaido University School of Medicine, Sapporo, Japan. noriwo@radi.med.hokudai.ac.jp
Shirato
Hiroki
H
Aoyama
Hidefumi
H
Onimaru
Rikiya
R
Suzuki
Keishiro
K
Hida
Kazutoshi
K
Miyasaka
Kazuo
K
Iwasaki
Yoshinobu
Y
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D019583:Dose Fractionation, Radiation; D005260:Female; D005910:Glioma / Q000401:mortality / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013120:Spinal Cord Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D016019:Survival Analysis