Material and Method: The present study was retrospective. Patients who underwent surgery and were diagnosed with low-grade gliomas between January 2000 and October 2009 were recruited. Time to recurrence and malignant transformation were analyzed using Kaplan-Meier method and multivariate Cox proportional hazard regression models.

Results: Seventy-seven patients underwent surgery for low-grade glioma. The pathological reports were diffuse astrocytoma in 55 patients (71%), oligodendroglioma in 19 patients (25%), and oligoastrocytoma in three patients (4%). The types of tumor resection were biopsy in 39 patients (50%), subtotal resection 34 patients (44%), and total resection in four patients (5%). The overall mean time to follow-up was 40 months, the median recurrence and malignant transformation times were 14 and 24 months. The 5-year recurrence-free and malignant-free survival rate was 50% and 68%. Factors associated with tumor recurrence were age, sex, presenting symptoms, preoperative Karnofsky performance status (KPS) score, tumor volume, and contrast enhancement. None of these factors showed statistically significant association with malignant transformation.

Conclusion: One fourth of the patients had tumor recurrence and malignant transformation in a short period of time. Delayed recurrence and malignant transformation after primary resection are associated with several factors. The type of surgery especially total-subtotal resection might favor prognosis.

Keywords: Recurrence, Malignant transformation, Low-grade gliomas, Recurrence-free survival rate, Malignancy-free survival rate