P11.40.A ANALYSIS OF THE ROLE OF SUPRAMARGINAL RESECTION IN INFILTRATIVE BRAIN METASTASES. A RANO-RESECT BASED STUDY

Abstract BACKGROUND Surgery is a key element in brain metastases (BM) treatment. While gross total resection (GTR) appears beneficial, little evidence is available on supramarginal resection and its role in BM management. Moreover, given the recent advances in the study of infiltrative histological growth patterns (HGP) in brain metastases, a study regarding supramarginal resection of brain metastases becomes necessary. We, therefore, aimed to analyze the impact of supramarginal resection on BM patient’s outcomes. MATERIAL AND METHODS 16.00 We analyzed 353 patients (162 female, 191 male) with a median age of 62.8 years (range: 23.4 - 86.2 years) who underwent surgical resection of one or several BM. Patients presented with multiple metastases in 45.5%, singular in 36.7%, and solitary in 17.8%. Fluorescence guidance (FG) was used in 207 patients (58.6%). Supramarginal resection was determined by volumetry of the pre-and postsurgical FLAIR- or non-contrast enhancing (non-CE) tumor volume as previously defined by the RANO resect group for primary brain tumors. In addition, we divided “infiltrative metastasis (IN)” from “non-infiltrative metastasis (NIN)”, according to a previously established radiological classification. Outcome analysis included progression-free (PFS) and overall survival (OS). RESULTS 264 (74.8%) patients underwent a complete CE resection. In 52.4% of these patients, we could identify an additional supramarginal resection. The extent of supramarginal resection was significantly higher in the FG group (p=0.004). Preoperative non-CE volume was significantly higher in the IN group compared to NIN group (p=0.022). Supramarginal resection improved OS in patients with multiple metastases (p=0.023); PFS was prolonged in younger patients (p=0.020) and in those who did not receive adjuvant systemic treatment (p=0.008). PFS was negatively influenced by residual FLAIR volume in patients without disease control (p=0.035), no adjuvant systemic (p=0.009), or radiotherapy (p=0.027). Multivariate Cox regression analysis revealed age (p=0.013) and the extent of supramarginal resection (p=0.020) as independent positive prognostic factors for OS in patients with multiple metastases. CONCLUSION Supramarginal resection was beneficial for both, PFS and OS in specific subgroups of BM patients. Fluorescence guidance greatly increased the extent of supramarginal resection. Preoperative non-CE volume was significant higher in metastases with an infiltrative HGP, highlighting the importance of supramarginal resection in this group of patients.