Neurophysiological evaluation of late effects of adjuvant high-dose chemotherapy on cognitive function

Objectives: To evaluate late neurotoxicity of adjuvant high-dose (HD) chemo therapy versus standard-dose (SD) chemotherapy by event-related potentials (ERP) and quantitative electroencephalography (qEEG). Patients and methods: From a randomized study in high-risk breast cancer pa tients on the efficacy of high-dose versus standard-dose adjuvant chemother apy, late effects on cognitive functioning were analyzed by neuropsychologi cal tests. Cognitive impairment was found in 32% of the HD group, 17% of th e SD group and in 9% of a control group of stage I breast cancer patients n ot treated with chemotherapy. In 17 consecutive patients in the HD group an d 16 consecutive patients in the SD group neurophysiological tests were per formed, consisting of P300 and qEEG. Results of patients treated with chemotherapy were compared with results of 14 control patients not treated with chemotherapy. All patients were teste d two years after treatment. Results: Asymmetry of the alpha rhythm of grea ter than or equal to0.5 Hz was found in 7 HD patients, 2 SD patients and in none of the control patients (p = 0.01). No differences were found between the groups with regard to frequency of alpha rhythm, alpha blocking and la tency of P300. No correlation was found between neurophysiological paramete rs and neuropsychological performance, except for an overall relation betwe en the P300 latencies and the total number of deviant test scores. Conclusion: Although the neurophysiological differences are subtle and the relation with the cognitive functioning in individual patients as measured by the neuropsychological examination is equivocal, the results suggest tha t there is neurophysiological support for cognitive dysfunction as a late c omplication of high-dose systemic chemotherapy in breast cancer.