Long term course of WHO grade II astrocytomas of the Insula of Reil after I-125 interstitial irradiation.
OBJECTIVE
To present long-term results after interstitial iodine-125 irradiation of adult patients with de-novo World Health Organization (WHO) Grade II astrocytomas and oligoastrocytomas of the insula of Reil with special respect to the treatment-related risk.


METHODS
55 consecutively treated patients (from 1979 to 1992) with circumscribed tumors with a diameter < 5 cm (astrocytomas: 46 patients, oligoastrocytomas: 9 patients) were included. The reference dose-calculated to the outer boundary of the tumor-was in the range of 60-100 Gy and the dose rate was low (< 10 cGy/h). Progression-free survival, risk of malignant transformation, survival, and the incidence of radiogenic complications were estimated by the Kaplan-Meier method. Prognostic factors were obtained from the Cox-model.


RESULTS
Median follow up for the survivors was > 10 years. 5-year (10-year) progression-free survival was 40.7 % (20.2 %), and 5-year (10-year) survival 54.6 % (28.4 %). Malignant transformation occurred in 42.4 % after 5 years. Neither of the Kaplan-Meier curves showed a leveling off over time. Transient (progressive) radiogenic complications were observed in 13 [4] patients (one-year overall complication rate: 18%), and were significantly associated with a tumor diameter >3.5 cm (p<0.001). No long term side-effects were detected and delayed external beam irradiation (in case of tumor progression) did not enhance the risk. Tumor enhancement on CT was the only unfavorable predictor for survival.


CONCLUSIONS
A limited overall prognosis for adult patients with insular WHO grade II astrocytomas and oligoastrocytomas was detected. Interstitial I-125 irradiation offers a minimal-invasive and low-risk treatment option for circumscribed tumors with a diameter < 3.5 cm. Larger tumors require further evaluation for optimal treatment.
Mehrkens
Jan H
JH
Neurochirurgische Klinik, Klinikum Grosshadern, Ludwig-Maximilians-Universität, München, Marchioninistr. 15, 81377, München, Germany.
Kreth
Friedrich W
FW
Muacevic
Alexander
A
Ostertag
Christoph B
CB
D000328:Adult; D001254:Astrocytoma / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000532:radiotherapy*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000401:mortality / Q000532:radiotherapy*; D002471:Cell Transformation, Neoplastic; D002540:Cerebral Cortex; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014944:World Health Organization
D007457:Iodine Radioisotopes