Hypofractionated high-dose irradiation for the treatment of malignant astrocytomas using simultaneous integrated boost technique by IMRT.
OBJECTIVE
We evaluated the clinical significance of hypofractionated high-dose irradiation using simultaneous integrated boost technique with intensity-modulated radiation therapy (IMRT) for the treatment of malignant astrocytomas (MAs).


METHODS
Twenty-five patients with MAs were treated by IMRT. Three layered planning target volumes (PTVs) were contoured. PTV-1 was the area of enhanced lesion with 5-mm margin; PTV-2 was the area with 15-mm margin surrounding the PTV-1; PTV-3 was the area of perifocal edema. Irradiation was performed in 8 fractions, and only the dose for PTV-1 was escalated from 48 Gy to 68 Gy while maintaining the dose for PTV-2 (40 Gy) and PTV-3 (32 Gy). The clinical outcome of IMRT was compared with 60 MA patients treated by conventional external beam irradiation (EBI).


RESULTS
The progression-free survival of patients in the IMRT group was significantly longer than that in the EBI group (p < 0.0001). No distant failure was observed in both groups. In the IMRT group, dissemination was the most frequent cause of death (70%). The overall survival of patients in the IMRT group was better than that in the EBI group (p = 0.043).


CONCLUSIONS
Our regimen of IMRT contributed to the control of both the regional and infiltrating tumors, resulting in better survival of patients.
Division of Neurological Surgery, Chiba Cancer Center, Chiba, Japan.
Toshihiko
T
Iuchi
Kazuo
K
Hatano
Yuichiro
Y
Narita
Takashi
T
Kodama
Tomohiro
T
Yamaki
Katsunobu
K
Osato
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001254:Astrocytoma / Q000134:cerebrospinal fluid / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D001932:Brain Neoplasms / Q000134:cerebrospinal fluid / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000134:cerebrospinal fluid / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D016019:Survival Analysis