NIMG-54. DIFFUSE TUMOR GROWTH PATTERN IS ASSOCIATED WITH WORSE OUTCOME ONLY IN IDH WILDTYPE BUT NOT IN IDH MUTANT GLIOMAS WHO II AND III

Abstract

Abstract BACKGROUND Magnetic resonance imaging (MRI) based characterization has previously shown heterogeneity in tumor appearance according to IDH mutation status. We have recently investigated the relevance of contrast enhancement to be dependent on IDH mutation status in glioma WHO II and III. Here, we aimed at further characterizing tumor growth patterns and their prognostic value in these tumors. METHODS MRI and clinical data of patients with newly diagnosed glioma WHO II and III from two different centers were retrospectively reviewed. Radiological data such as localization, presence of contrast enhancement, T2-volume as well as tumor growth pattern (“diffuse” vs. “circumscript”) were obtained. Progression-free (PFS) and overall survival (OS) were determined and correlated with clinical, radiological and molecular characteristics using univariate and multivariate regression analyses. RESULTS 390 patients were included, 69% thereof having an IDH mutation. The median T2-volume was 46.0 ml, IDH mutant tumors being larger (50.7 ml) than IDH wildtype tumors (36.0 ml), p = 0.01. A total of 172 tumors were classified as “circumscript” and 218 as “diffuse”; the majority of IDH wildtype tumors (71%) were well delineated compared to 51% in the IDH mutant group (p< 0.0001). Apart from clinical parameters such as younger age, lower KPS, complete resection and delayed treatment, “circumscript” tumor growth pattern was associated with improved survival in the entire group (p = 0.016). When analyzed according to IDH mutation status, “circumscript” tumor growth pattern was significantly associated with OS and PFS (p = 0.006 and p = 0.002) in the IDH wildtype, but not in the IDH mutant group (p = 0.34 and p = 0.81). CONCLUSION IDH wildtype tumors present more often with a ”circumscript” growth pattern on initial T2 MRI. However, this “circumscript” growth pattern was associated with improved survival only in the IDH wiltdtype but not in the IDH mutant group.