Merritt-Putnam Symposium | Tumor-Associated Epilepsy and Epilepsy-Associated Tumors: Exploring the Bidirectional Crosstalk Between Tumors and Seizures.

Links between cancerous and noncancerous brain tumors and epilepsy have long been recognized. However, recent clinical and preclinical studies emphasize that not only do tumors impinge on surrounding brain tissue in ways that promote hyperexcitability and epileptogenesis, but that neural activity also influences tumor progression. In this review, inspired by the Merritt-Putnam Symposium of the 2025 meeting of the American Epilepsy Society, we present a cross-disciplinary dialog between cancer and epilepsy research, including discussion of tumors and epilepsies that are more prominent in pediatric versus adult populations. First, we discuss the neuropathology, genetics, and surgical outcomes of epileptogenic brain tumors, and associated mechanisms of epileptogenesis. Second, we evaluate tuberous sclerosis complex as a model disease for clinical and mechanistic investigation of tumor-epilepsy relationships. Third, we review recent evidence for somatic gene mutations as underlying factors in hypothalamic hamartomas. Lastly, we present evidence for bidirectional relationships between gliomas and neuronal activity.