Trajectory of long-term neuropsychological performances and cognitive-deterioration-free survival after hippocampus-sparing whole-brain radiotherapy in cancer patients mostly with newly diagnosed brain oligometastases

Neurocognitive functions (NCFs) might change after conventional whole-brain radiotherapy (WBRT). The technique of hippocampus sparing during WBRT (HS-WBRT) may substantially preserve NCFs. Therefore, the aim of this study was to examine whether trajectories of neuropsychological performances maintained or improved after HS-WBRT. A total of 125 cancer patients underwent the HS-WBRT course. Before HS-WBRT, all participants underwent multidomain neurocognitive assessment, mainly involving executive functions and hippocampus-related memory. After radiotherapy, the above assessment was administered at regular time points to monitor longitudinal neuropsychological performances. The delta values of post-radiotherapy and baseline NCF scores showed a sustained trend, signifying cognitive maintenance rather than deterioration. This trend was observed for hippocampus-related verbal memory and frontal-lobe-related executive functions, represented by the score of Word List-immediate memory and Modified Card Sorting Test - Complete Categories, respectively. The potential predictors of longitudinal multidomain neuropsychological performances included age at enrollment, baseline NCF scores, and the assessment time (months) elapsed since enrollment, signifying the trajectory of patients' neuropsychological performances after HS-WBRT. Among longitudinal neuropsychological outcomes, there was a considerable time trend toward maintenance in verbal learning immediate memory [odds ratio, 1.112, 95% confidence interval, 1.08 - 1.15], which persisted even after adjusting for the most independent predictor (baseline NCF scores). Functional preservation of longitudinal multidomain neuropsychological performances was evident after HS-WBRT. Such neurocognitive preservation, particularly hippocampus-related memory functions, was meaningfully sustained in our patients after undergoing the standardized course of hippocampus sparing during WBRT.