Analysis of outcomes of patients with oligodendroglioma with focus on volumetric reduction.

Background: This study aims to evaluate the surgical outcomes and prognostic factors influencing overall survival (OS) and progression-free survival (PFS) in patients with molecularly confirmed oligodendrogliomas focussing on the extent of resection (EOR) and volumetric analysis. Methods: We conducted a retrospective analysis of 115 adult patients with oligodendroglioma at our institution from January 2010 to December 2020. Inclusion criteria encompassed histologically and molecularly confirmed grade 2 and 3 oligodendroglioma, age above 18 years, availability of pre- and postoperative imaging, and complete follow-up data. Surgical outcomes were categorized by EOR and volumetric assessments were performed using neuroimaging. Mean OS and PFS were calculated using the Kaplan-Meier method (As mortality was < 50%) and univariate/multivariate analyses were conducted to identify prognostic factors. Results: The cohort had a median age of 42 years (range 18-77), with GTR achieved in 47% of primary operations. Median follow-up was 6.3 years. OS was significantly influenced by age (p < 0.0001) and EOR, with a mean OS of 134 months and a mean PFS of 117 months. Volumetric reduction of tumor volume greater than 80% correlated positively with both OS and PFS. The analysis also highlighted the importance of adjuvant therapy in improving PFS. Conclusion: This study confirms that younger age, extensive volumetric reduction, and intraoperative adjuncts are associated with improved OS and PFS in patients with oligodendroglioma. While the EOR impacts OS significantly in grade 3 tumors, further research is necessary to determine optimal surgical strategies for grade 2 oligodendrogliomas.