Object: Unlike their malignant counterparts, low-grade gliomas are associated with prolonged survival. However, these tumors have a propensity to progress after resection and ultimately undergo malignant degeneration. The factors associated with recurrence and malignant degeneration remain relatively unknown. The authors set out to determine factors that were independently associated with recurrence and malignant degeneration in patients who underwent resection of a hemispheric low-grade glioma.
Methods: Adult patients who underwent craniotomy and resection of a hemispheric low-grade glioma (WHO Grade II) at the Johns Hopkins Medical Institution's academic tertiary-care institution between 1996 and 2006 were retrospectively reviewed. Multivariate proportional hazards regression analyses were used to identify associations with tumor recurrence and malignant degeneration.
Results: Of the 191 consecutive patients with low-grade gliomas in this series (89 fibrillary astrocytomas, 89 oligodendrogliomas, and 13 mixed gliomas), 83 (43%) and 44 (23%) experienced tumor recurrence and malignant degeneration at last follow-up, respectively. The 5-year progression-free and malignancy-free survival rates were 44 and 74%, respectively. Independent predictors of recurrence were duration of longest lasting symptom (relative risk [RR] 0.978, 95% CI 0.954-0.996, p = 0.01), tumor size (RR 1.328, 95% CI 1.109-1.602, p = 0.002), and preoperative contrast enhancement (RR 2.558, 95% CI 1.241-5.021, p = 0.01). Independent factors associated with malignant degeneration were fibrillary astrocytoma pathology (RR 1.800, 95% CI 1.008-4.928, p = 0.04), tumor size (RR 1.086, 95% CI 1.044-1.358, p = 0.04), and gross-total resection (RR 0.526, 95% CI 0.221-1.007, p = 0.05).
Conclusions: The identification and consideration of factors associated with recurrence and malignant progression may help guide treatment strategies aimed at delaying recurrence and preventing malignant degeneration for patients with hemispheric low-grade gliomas.