Prognostic Importance Of Ki-67 Labeling Index In Who Grade Ii Glial Tumors

World Health Organization (WHO) grade II gliomas are very heterogeneous types of gliomas and there is still significant disagreements between clinicians concerning the optimal treatment modality. Up until know a number of methods for predicting the prognostic subgroups of LGGs have been identified. These identified methods have some limitations in predicting the clinical outcome and survival. So we aimed to determine the predictive role of Ki-67 Labeling index (LI) on tumor behavior and survival. Between 1995 and 2014, the adult patients who had been irradiated at our departments with WHO grade II glial tumors were evaluated in this retrospective study. At our clinics, postoperative early-radiotherapy (RT) frequently applied for patients with which can not be resected totally or for patients who are suspected to have high risk features whereas delayed-RT frequently applied for patients with recurrence or progression. The patients received RT with 1.8-2 Gy fraction doses, five days a week for a total dose of median 54 Gy to the tumor or tumor bed with 1-2 cm margin. At least two experienced neuropathologist re-defined all the histological tissues retrospectively. Statistical analyses were performed using Statistical Package for Social Sciences Software, v 13.0 (Chicago, IL, USA). This present study included in 78 adult patients with median 44 (range; 6-137) months follow-up. Surgery was the initial treatment approach for all patients. 51 patients received adjuvant early-RT while 27 patients received delayed-RT. 72/78 specimens were Ki-67 positive. The mean overall survival (OS) was 88 (range; 73-102) months. 2-, 5- and 10- year OS rates were 90%, 70% and 40%, respectively. Patients with ≥40 years old had a poorer OS than patients with <40 years old (p=0.04). Patients with gross total resection or subtotal resection had a longer OS than patients with biopsy (Bx) or parsial resection (PR) (p=0.001). If the disease had recurrence or progression during the follow-up period, the patients had a poorer OS (p=0.01). Patients with a Ki-67 LI value ≥4% had a poorer OS than patients with a Ki-67 LI value <4% (p=0.001). According to multivariate analysis; recurrence or progression (HR=11.10, 95% CI, 2.19-56.20), Bx or PR (HR=8.22, 95% CI, 2.47-27.36) and Ki-67 LI value ≥4% (HR=5.06, 95% CI, 1.79-14.25) were the poor prognostic factors that affect OS. The mean progression-free survival (PFS) was 67 (range; 56-77) months and the extent of resection was the only independent prognostic factor that affect PFS. According to our current study, the extent of surgery, recurrence or progression, and Ki-67 LI ≥4% were the independent prognostic factors predicting OS. In addition, the extent of surgery was the only independent prognostic factor that affect PFS. In our opinion, the Ki-67 LI value is an important prognostic factor for WHO grade II glial tumors but this value can not be used alone as a diagnostic measure. It must be combined with the other prognostic factors.