Malignant supratentorial astrocytoma treated with postoperative radiation therapy: prognostic value of pretreatment quantitative diffusion-weighted MR imaging.
OBJECTIVE
To retrospectively evaluate whether the minimum apparent diffusion coefficient (ADC) of the tumor seen on pretreatment magnetic resonance (MR) images is of prognostic value in patients with malignant supratentorial astrocytoma.


METHODS
The study was approved by the institutional review board; the requirement for informed patient consent was waived. Between June 1996 and November 2003, 79 patients (44 male, 35 female; age range, 16-76 years) with malignant supratentorial astrocytoma underwent pretreatment MR imaging. Patient age, symptom duration, neurologic function, mental status, Karnofsky performance scale (KPS) score, extent of surgery, histopathologic diagnosis, tumor component enhancement, and minimum ADC were assessed at factor analysis of survival. Radiation Therapy Oncology Group-recursive partitioning analysis (RTOG-RPA) criteria were used to validate the prognostic value of the minimum ADC. Kaplan-Meier survival curves, the log-rank test, and the multivariate Cox proportional hazards model were used to evaluate the prognostic factors.


RESULTS
Twenty-nine patients had anaplastic astrocytoma, and 50 had glioblastoma multiforme. The minimum ADC was significantly lower in patients with glioblastoma multiforme than in those with anaplastic astrocytoma (P < .001). The two-year survival rates associated with low (<or=1.0 x 10(-3) mm(2)/sec) and high (>1.0 x 10(-3) mm(2)/sec) minimum ADCs were 14% (six of 42 patients) and 84% (31 of 37 patients), respectively (P < .001). The minimum ADC was the most important prognostic factor (hazard ratio = 10.459; 95% confidence interval: 5.113, 21.396) and could be used to assign patients to different prognostic groups in each RTOG-RPA class.


CONCLUSIONS
The minimum ADC at pretreatment MR imaging is a useful clinical prognostic biomarker for survival in patients with malignant supratentorial astrocytoma.
Murakami
Ryuji
R
Department of Radiation Oncology, Kumamoto University Hospital, Kumamoto 860-8556, Japan. murakami@kaiju.medic.kumamoto-u.ac.jp
Sugahara
Takeshi
T
Nakamura
Hideo
H
Hirai
Toshinori
T
Kitajima
Mika
M
Hayashida
Yoshiko
Y
Baba
Yuji
Y
Oya
Natsuo
N
Kuratsu
Jun-Ichi
J
Yamashita
Yasuyuki
Y
D000293:Adolescent; D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods; D011379:Prognosis; D018714:Radiotherapy, Adjuvant / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015173:Supratentorial Neoplasms / Q000175:diagnosis* / Q000628:therapy*; D016896:Treatment Outcome