Objective: We reviewed the relationship between extent of resection and survival of patients with high-grade gliomas with special consideration of an oligodendroglial component. Methods: A retrospective review was performed on 160 adult patients with histological diagnosis of high-grade gliomas since 2000. All histological slides were categorized as high-grade astrocytomas or oligodendroglial tumors. Extent of resection was assessed by early post-operative magnetic resonance imaging and classified as complete resection, incomplete resection and biopsy. Measured outcomes were overall survival and progression-free survival. The independent association of extent of resection and survival was analyzed by the multivariate proportional hazard model adjusting for prognostic factors. Results: The lesions were classified as high-grade astrocytomas in 93 patients and high-grade oligodendroglial tumors in 67 patients. In high-grade astrocytomas, the median survival after complete resection (n = 36), incomplete resection (n = 36) and biopsy (n = 21) was 23.4, 15.3 and 12.6 months, respectively. Complete resection was independently associated with increased overall survival (P < 0.001) and progression-free survival (P = 0.002) compared with incomplete resection, while incomplete resection was not associated with survival benefit compared with biopsy by multivariate analysis. On the other hand, in high-grade oligodendroglial tumors, the majority of patients were still alive and there is no significant difference in the survival between complete resection (n = 24) and incomplete resection (n = 33), while even incomplete resection had a significantly longer overall survival (P < 0.001) and progression-free survival (P = 0.006) compared with biopsy (n = 10). Conclusions: Maximal cytoreduction improves the survival of high-grade gliomas, although our data indicated that the impact of extent of resection in high-grade astrocytomas is different from that in high-grade oligodendroglial tumors.
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