Cognitive functions of adolescent childhood cancer survivors assessed by event-related potentials

Background. Neurophysiological methods were applied to examine subtle centr al nervous system (CNS) adverse effects for adolescent childhood cancer sur vivors. We analyzed auditory event-related potentials (ERPs)-P300 and MMN/P 3a complex-to find out whether there was impaired attention orientation in asymptomatic cancer survivors, and whether these ERP methods could be used as more objective tools in detecting those survivors who might need academi c testing. Previous clinical studies of P300 have focused on leukemia survi vors. MMN for cancer survivors has not been reported. Procedure. The subjec ts were survivors of childhood leukemia (n=11) and solid tumors (n=8), as w ell as healthy controls (n=10). The mean age was 15.5 years for survivors a nd 15.9 years for controls. Pure sinewave tones (500 and 553 Hz, 100 ms) we re used as stimuli in an oddball paradigm. The ERPs to frequency change wer e measured. MMN recordings were performed in a passive non-attended situati on where the subject was watching a voiceless video cartoon. P300 was produ ced thereafter, but in an active attend situation, by the same auditory odd ball paradigm as MMN. Results. A significant difference was detected betwee n the groups for the latency of P300 at electrodes Cz (P = 0.03) and C4 (P = 0.05). The cancer survivors had prolonged P300 latencies as an indication of prolonged short-term memory processing. The area and latency parameters of MMN did not differ significantly between the study groups, but in cance r survivors, the area and the mean amplitude of the subsequent P3a wave wer e diminished. The results indicate that the discrimination process was not as easy for the survivors as for the controls. However, it seems that in ca ncer survivors the basic mechanism starting attention shift to novel stimul i is not impaired. Conclusions. These results indicate that it is important to carefully evaluate the proper methods for the teaching of children who are survivors of malignancies. The auditory information may not always lead to the best possible learning results. Med. Pediatr. Oncol. 36:442-450, 20 01. (C) 2001 Wiley-Liss, inc.