Gabapentin Dosing in Retrospective GBM Studies
The provided evidence does not contain information about gabapentin dosing used in retrospective studies for GBM treatment. The guidelines and drug labels focus exclusively on gabapentin's FDA-approved indications (epilepsy and postherpetic neuralgia), not glioblastoma therapy.
What the Evidence Actually Shows
FDA-Approved Dosing (Not for GBM)
The gabapentin FDA label 1 describes dosing only for:
- Epilepsy: 900-1800 mg/day in divided doses (studies used 600-1800 mg/day range)
- Postherpetic neuralgia: Not specified in excerpts provided
Recent Retrospective GBM Research
Two recent retrospective studies 2, 3 examined gabapentin use in GBM patients but do not specify the actual doses used:
2025 SEER-Medicare study 2: Analyzed 146 patients receiving "post-diagnostic gabapentin" but provided no dosing information. Showed 47% decreased hazard of death compared to standard treatment alone (p<0.001).
2025 multi-institutional cohort 3: Examined 1,072 patients across discovery and validation cohorts who received gabapentin after GBM resection, but again no specific doses were reported. The study focused on survival benefit and thrombospondin-1 levels as a biomarker.
Critical Gap in the Literature
The retrospective studies examining gabapentin in GBM do not report the specific doses administered to patients. This represents a significant limitation, as:
- Patients likely received gabapentin for seizure management (a common GBM complication), not as primary cancer therapy
- Dosing was probably individualized based on seizure control needs, not standardized for research purposes
- The survival benefits observed may be dose-dependent, but this cannot be determined from available data
Clinical Context
The 2022 ASCO-SNO guidelines 4 and 2021 EANO guidelines 5 make no recommendations regarding gabapentin for GBM treatment—only for seizure management when clinically indicated. The 2020 ASCO guideline 6 explicitly states gabapentin lacks evidence for chemotherapy-induced peripheral neuropathy, contradicting common insurance requirements.
Bottom line: The retrospective GBM studies showing potential survival benefit with gabapentin do not report the doses used, making it impossible to provide specific dosing recommendations based on this evidence.