We retrospectively evaluated medical records of 67 patients with malignant glioma receiving temozolomide. All patients received concomitant radiotherapy and temozolomide followed by adjuvant temozolomide. In case of any radiological or clinical progression, MRI spectroscopy evaluation was used to confirm tumoral progression.
Radiological or clinical progression was observed in 17 (25.4 % ) patients. Early radiation induced necrosis was diagnosed in 4 of 17 patients (23.5 % ) by surgery (n = 3) and MRI spectroscopy (n = 1). The observed incidence of pseudoprogression was 4 in 67 (6 % ) patients. Patients with diagnosis of early radiation injury had median progression-free survival of 7 months compared to 5 months in patients without radiation damage (p = 0.004). However, there was no statistically significant difference in terms of overall survival between groups.
Temozolomide can cause early radiation induced injury which can mimic progressive tumor. Although the discrimination between two entities results in the accurate evaluation of response to therapy and benefits those patients, it did not affect overall survival. MRI spectroscopy is a valuable tool to define early radiation necrosis and should be further evaluated in larger prospective studies.