External irradiation models for intracranial 9L glioma studies

9L cells were implanted in the striatum of twenty 344-Fisher rats to induce a brain tumor. On day 8, animals were randomized in two groups: an untreated group and an irradiated group with three fractions of 6 Gy at day 8, 11 and 14. Survival and toxicity were assessed.Irradiated rats had significantly a longer survival (p = 0.01). No deaths occurred due to the treatment. Toxicities of reduced weight and alopecia were increased during the radiation period but no serious morbidity or mortality was observed. Moreover, abnormalities disappeared the week following the end of the therapeutic schedule.Delivering 18 Gy in 3 fractions of 6 Gy every 3 days, with mild anaesthesia, is safe, easy to reproduce and allows for standardisation in preclinical studies of different treatment regimens glioma rat model.Malignant glioma is the most frequent primary brain tumor. Prognosis is extremely poor with current standards of treatment. Median survival is less than fifteen months with a multimodality treatment of surgery, radiotherapy (RT) and chemotherapy [1]. Temozolomide, a novel alkylating agent, has shown modest activity against recurrent glioma. However, in newly diagnosed patients with glioblastoma, temozolomide in combination with radiotherapy significantly prolongs survival. Radiotherapy represents a significant part of the treatment regimen for malignant glioma [2-4]. To be sufficiently efficacious with acceptable toxicity, RT consists of 30 fractions of 2 Gy each, usually administered Monday-Friday for 6-7 weeks (42 days) in the tumor volume with margins. The schedule is clearly defined and established in clinical practice [5]. Consequently, in preclinical studies evaluating adjuvant therapies, radiation therapy should be included. Previously, we used a fractionated radiation schedule delivering 36 Gy in 9 fractions of 4 Gy to treat C6 tumor bearing-rats [6]. We found that brain radiotherapy for rat 9L-glioma, which is the most common preclinical model used, is not standar