Functional brain activity in cancer-related cognitive impairment: a scoping review of EEG studies

Cancer-related cognitive impairment (CRCI) is reported across the cancer trajectory, yet its neurobiological basis remains incompletely understood. Electroencephalography (EEG) provides a temporally precise method for assessing brain activity at rest and during cognitive processing, but its application in CRCI research has not been systematically mapped. This scoping review characterized how EEG has been used to study cognitive functioning in people with cancer, including populations studied, EEG paradigms and analytic approaches employed, and cognitive outcomes assessed. Following PRISMA-ScR guidance, we searched MEDLINE, PsycINFO, and Web of Science from inception to February 2025 for studies using EEG to examine cognitive functioning. Sixty articles were included. Most were small and cross-sectional, with publication output increasing markedly after 2015. Task-based event-related potentials, particularly from oddball and attention tasks, were used most frequently, whereas quantitative EEG approaches, including spectral power and connectivity analyses, were less common. In populations with cancers outside the central nervous system (CNS), longer P300 latency and lower amplitude were common, but opposite and null findings also occurred. Evidence from primary CNS and other intracranial tumor populations was sparse. Across cancer contexts, quantitative EEG findings showed limited convergence across articles. Associations between EEG measures and cognitive outcomes were inconsistent and often not tested directly. Overall, EEG provides a complementary approach to investigating cognition in people with cancer, but the evidence remains methodologically heterogeneous. Larger longitudinal studies, more consistent cognitive outcome selection, and closer integration of neural and cognitive measures are needed to establish reproducible findings and evaluate their potential clinical utility.

https://www.crd.york.ac.uk/PROSPERO/view/CRD420251084951.