Risk factors for cognitive impairment in radically treated stage III NSCLC: Secondary findings of the NVALT-11 study

•Cognitive impairment is dynamic in individuals.•Cognitive impairment has 4 types: sustained, reversible, recurring, alternating.•Baseline cognitive impairment is the most important risk factor.•Cognitive functioning should be assessed at multiple time points.•Patients who have sustained cognitive impairment should avoid neurotoxic treatments. To identify risk factors for self-reported cognitive impairment in radically treated stage III non-small cell lung cancer (NSCLC). Cognitive functioning was assessed using the EORTC-QLQ-C30 at seven pre-specified time points in the phase III NVALT-11 trial (observation versus prophylactic cranial irradiation [PCI] in stage III NSCLC treated with chemo-radiotherapy ± surgery). Cognition was analyzed as binary (impairment or not) and continuous outcome, respectively, using generalized estimating equation (GEE) before and after multiple imputation. A score