LOW GRADE DIFFUSE ASTROCYTOMA - PROGNOSTIC FACTORS TO ANAPLASTIC TRANSFORMATION

INTRODUCTION: Low grade gliomas (LGG) comprise nearly 20% of all central nervous system (CNS) glial tumors. LGG are characterized by their infiltrative growth and frequent tumor recurrence with malignant progression. They have a heterogeneous clinical behavior being histological, first line resection, velocity of diameter tumor expansion during pretherapeutic period,tumor volume, contrast enhancement and patients' characteritics the only described factors for identifying patients at risk of progression. The identification and validation of new imaging prognostic factors would help to minimize potential treatment-related side effects in LGG. OBJECTIVE: The aim of our study was to analyze the impact of clinical (gender, age, first symptom), histological (gemistocytic) and neuroimaging (tumor growth ratio at 6 months- GR6m) factors on malignant progression in a cohort of diffuse low grade astrocytomas. We conducted serial volumetric analysis using Flair sequences. The time to malignant progression (TMP) was defined as time between histological diagnose and first MRI showing contrast enhancement or histology proven progression. RESULTS: Patients' mean age was 42.5 ± 14.6 years with a male:female ratio of 1.7:1. Median Pignatti index (PI) was 2 (1-4). The median TMP was of 4.76 (0.33-11.8) years. Nearly half (48.2%) of the patients showed a malignant progression. This group had a higher GR6m (49% versus 3%, p = 0.032). A cut-point of GR6m < 2% obtained by ROC analysis showed a sensitivity and specificity of 92.3% and 71% (p = 0.001). In the multivariate analysis the GR6m < 2% (HR: 5.23, 95% CI (1.4-19.61), P = 0.014), gemistocytic component (HR 8, 95% CI (1.6-39.3), p = 0.01) and a PI of 3-4 (HR : 6.94, 95% CI (1.64-29.4), p = 0.008) were identified as independent predictors of TMP. CONCLUSIONS: GR6m resulted as independent prognostic factor of TMP. In addition, our study confirmed PI and gemystocitic histology as prognostic factors on TMP.It is important to define new prognostic factors to anaplastic transformation due to individualized treatment in patients.