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.
Iuchi
Toshihiko
T
Division of Neurological Surgery, Chiba Cancer Center, Chiba, Japan.
Hatano
Kazuo
K
Narita
Yuichiro
Y
Kodama
Takashi
T
Yamaki
Tomohiro
T
Osato
Katsunobu
K
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