Objective: It remains unknown whether the extent of surgical resection affects survival or disease progression in patients with supratentorial low-grade gliomas.
Methods: We conducted a retrospective cohort study (n = 170) between 1996 and 2007 at a single institution to determine whether increasing extent of surgical resection was associated with improved progression-free survival (PFS) and overall survival (OS). Surgical resection of gliomas defined as gross total resection (GTR) (complete resection of the preoperative fluid-attenuated inversion recovery signal abnormality), near total resection (NTR) (<3-mm thin residual fluid-attenuated inversion recovery signal abnormality around the rim of the resection cavity only), or subtotal resection (STR) (residual nodular fluid-attenuated inversion recovery signal abnormality) based on magnetic resonance imaging performed less than 48 hours after surgery. Our main outcome measures were OS, PFS, and malignant degeneration-free survival (conversion to high-grade glioma).
Results: One hundred thirty-two primary and 38 revision resections were performed for low-grade astrocytomas (n = 93) or oligodendrogliomas (n = 77). GTR, NTR, and STR were achieved in 65 (38%), 39 (23%), and 66 (39%) cases, respectively. GTR versus STR was independently associated with increased OS (hazard ratio, 0.36; 95% confidence interval, 0.16-0.84; P = 0.017) and PFS (HR, 0.56; 95% confidence interval, 0.32-0.98; P = 0.043) and a trend of increased malignant degeneration-free survival (hazard ratio, 0.46; 95% confidence interval, 0.20-1.03; P = 0.060). NTR versus STR was not independently associated with improved OS, PFS, or malignant degeneration-free survival. Five-year OS after GTR, NTR, and STR was 95, 80, 70%, respectively, and 10-year OS was 76, 57, and 49%, respectively. After GTR, NTR, and STR, median time to tumor progression was 7.0, 4.0, and 3.5 years, respectively. Median time to malignant degeneration after GTR, NTR, and STR was 12.5, 5.8, and 7 years, respectively.
Conclusion: GTR was associated with a delay in tumor progression and malignant degeneration as well as improved OS independent of age, degree of disability, histological subtype, or revision versus primary resection. GTR should be safely attempted when not limited by eloquent cortex.