P16.14 Treatment of thalamic glial lesions: surgery versus biopsy

Introduction: Thalamic tumors are a heterogeneous subset of deep lesions linked by topographical and behavioral features that recently re-gained interest in neurosurgical community. Glioma represents the most frequent neoplastic lesion in this site, and the treatment is still debated. With the present study we aimed to retrospectively analyze clinical, radiological and pathological data of patients affected by thalamic gliomas treated at our institution over the last 10 years, to better define indications for surgical treatment or tumor biopsy. Material and Methods: Pathology and surgical databases IRB-approved from our Neurosurgical Department were retrospectively reviewed to identify patients with histological diagnosis of thalamic gliomas. Clinical pre-operative and post-operative data along with demographic, histological, follow-up information and surgical treatment modalities were collected. Correlations between different variables (tumor grade, extent of resection, pediatric or adult age, post-operative Karnofsky Performance Status (KPS)) were evaluated using univariate analysis according to the Kaplan-Meier method. A p-value ≤ 0.05 was considered significant. Results: There were 55 patients (22 m, 33 f, mean age 37y), with a mean pre-operative volume of 52 cm3 in the surgery group (SG) and 32 cm3 in the biopsy group (BG). 31 patients underwent surgical resection while 24 underwent stereotactic or frameless biopsy. Early (within 72 hrs) post-operative mortality was 3% in the SG, and null in BG. After 3 months we observed a decrease in KPS greater than 10 points in 5 patients in SG and in 8 patients in BG. 2 patients in each group died within 3 months due to tumor progression. In the early post-operative period the mean KPS decreased in the SG while it was stable in the BG; this trend progressively turned around in the following months, due to medical and rehab therapy in the SG and disease progression in BG. In SG, the 25 patients who recovered the pre-operative clinical status within 3 months presented a significant increase in overall survival (OS) compared to BG (p = 0,01). OS was significantly longer in the SG compared to the BG (27mo. vs 11mo. respectively; p = 0,02). A gross total or subtotal resection was positively associated with an increase in OS (p = 0,01). Moreover, a pre-operative tumor volume exceeding 32 cm3 was significantly associated (p = 0,03) with a decrease in the OS. Although there were no statistical differences (p = 0,16) in terms of OS between adult and pediatric patients (<18 years), there was anyway a trend towards a longer OS period in the last group (16mo. vs 34mo. in the entire population, and 13mo. vs 22mo. in the SG). Conclusion: Surgery is showed to be a safe alternative to biopsy in thalamic gliomas. This option may improve prognosis as depicted by our data. When surgery is performed, the extent of resection represents the most important prognostic factor in terms of OS.