Prognostic Significance of Contrast Enhancement in Newly Diagnosed Grade 2 IDH-mutant Glioma

Background Contrast enhancement is generally considered an adverse prognostic feature in adult glioma. However, its significance in newly diagnosed grade 2 IDH-mutant glioma remains uncertain, with important implications for use of the mutant IDH inhibitor vorasidenib. We evaluated survival outcomes associated with preoperative enhancement in this population. Methods We retrospectively evaluated consecutive patients with grade 2 IDH-mutant glioma treated at two institutions between 2010 and 2021. Preoperative MRIs were assessed for intratumoral enhancement by two independent readers with third-reader adjudication. Overall survival (OS) and progression-free survival (PFS) were evaluated by Kaplan-Meier analysis, univariate and multivariable Cox regression. Results Among 325 evaluable patients, median age was 37 years, 47% had 1p/19q-codeletion, and 35% had gross-total resection. Median follow-up was 10.5 years. Preoperative enhancement was observed in 53 (16%) patients, most commonly nonmeasurable (72%) or ill-defined (62%); most (87%) had no residual postoperative enhancement. Preoperative enhancement was not associated with OS or PFS in either univariate analyses (OS HR 1.16 [0.67–2.01], p = 0.591; PFS HR 1.25 [0.88–1.80], p = 0.216) or multivariable analyses adjusting for established prognostic factors (OS HR 0.86 [0.46–1.61], p = 0.633; PFS HR 1.29 [0.86–1.92], p = 0.219). Enhancement characteristics (measurable size, well-defined morphology) were not associated with OS. Conclusion In grade 2 IDH-mutant glioma, preoperative enhancement was not associated with OS or PFS. These findings suggest that preoperative enhancement does not identify a higher-risk subgroup in this population, and that its presence alone should not preclude consideration of vorasidenib in eligible patients.