Romanian Neurosurgery (Dec 2010)
Malignant transformation of low grade gliomas into glioblastoma a series of 10 cases and review of the literature
Abstract
Background: Diffuse infiltrative low-grade gliomas (LGG) of the cerebral hemispheres in the adult are tumors with distinct clinical, histological and molecular characteristics. WHO (World Health Organization) classification recognizes grade II astrocytomas, oligodendrogliomas and oligoastrocytomas. Conventional MRI is used for differential diagnosis, guiding surgery, planning radiotherapy and monitoring treatment response. Advanced imaging techniques are increasing the diagnostic accuracy. Low-grade gliomas have been documented to undergo transformation into high-grade gliomas, and the time interval of this transformation has been reported to generally occur within 5 years in about 50% of patients diagnosed with low-grade gliomas. Methods: We have reviewed all adult patients operated on for hemispheric glioblastoma at N Oblu Hospital in Iasi between 2006 and 2009 and in particular those patients with secondary glioblastoma. Results: from the total 110 cases of glioblastoma, ten of them were secondary to malignant transformation of an previously operated low grade glioma. Of the 10 patients with secondary glioblastoma, the initial histology was: gr II astocytoma in 6 cases, oligoastocytoma in 2 cases and in oligodendroglioma in 2 cases. The mean patient age was 46.1± 0.9 years and the most frequent symptom was represented by seizures 70%, the mean time from the first symptom to diagnosis was 11,2 months. 40% of the cases had subtotal resection and 60% had total resection (defined by the surgeon at the time of operation). 5 patients received radiotherapy postoperatively, 2 received both radio and chemotherapy and 3 had no adjuvant treatment. In our series the median time to malignant transformation was 32,5 months. Conclusions: Younger age, normal neurological examination and oligodendroglial histology are favorable prognostic factors, total/near total resection can improve seizure control, progression-free and overall survival, mean while reducing the risk of malignant transformation. Early post-operative radiotherapy improves progression free but not overall survival. Chemotherapy can be useful both at recurrence after radiotherapy and as initial treatment after surgery to delay the risk of late neurotoxicity from large-field radiotherapy.
