Seizure response to temozolomide chemotherapy in patients with WHO grade II oligodendroglioma: a single-institution descriptive study.

BACKGROUND: Tumor-related epilepsy (TRE) is common in patients with low-grade oligodendrogliomas. TRE is difficult to control despite multiple antiepileptic drugs (AEDs) in up to 30% of patients. Chemotherapy has been used for treatment to avoid potential radiotherapy-related neurotoxicity. This study evaluates the effect of temozolomide on seizure frequency in a homogeneous group with World Health Organization (WHO) grade II oligodendrogliomas.
METHODS: A retrospective analysis was conducted of adult patients with WHO grade II oligodendrogliomas and TRE followed at Memorial Sloan Kettering between 2005 and 2015 who were treated with temozolomide alone either as initial treatment or for disease progression. All had seizures 3 months prior to starting temozolomide. Seizure frequency was reviewed every 2 cycles and at the end of temozolomide treatment. Seizure reduction of ≥50% compared to baseline was defined as improvement.
RESULTS: Thirty-nine individuals met inclusion criteria. Median follow-up since starting temozolomide was 6 years (0.8-13 years). Reduction in seizure frequency occurred in 35 patients (89.7%). Improvement was independent of AED regimen adjustments or prior antitumor treatment in 16 (41%); of these, AED dosage was successfully reduced or completely eliminated in 10 (25.6%). Twenty-five patients (64.1%) remained on a stable AED regimen. The majority (n = 32, 82%) had radiographically stable disease, 5 (12.8%) had objective radiographic response, and 2 (5.2%) had disease progression.
CONCLUSIONS: Temozolomide may result in reduced seizure frequency, and permit discontinuation of AEDs in patients with WHO II oligodendroglioma. Improvement was observed irrespective of objective tumor response on MRI, emphasizing the importance of incorporating seizure control in assessing response to tumor-directed therapy.