Screening of subclinical P300 event-related potentials changes in childhood acute lymphoblastic leukemia survivors

Modern treatment of childhood acute lymphoblastic leukemia (ALL) has resulted in a high cure rate; however, it can cause central nervous system toxicity. In the present study, a group of 136 ALL survivors were screened for changes in P300. Therapy was conducted according to a modified New York (NY) protocol (30 patients) and two subsequent revisions of a modified Berlin-Frankfurt-Munster (BFM) protocol (32 and 74 patients). The control group consisted of 58 patients. The survivors had significantly prolonged mean latency of P300 (331.31 +/- 28.71 vs. 298.14 +/- 38.76 msec, P<0.001) and reaction time (439.51 +/- 119.86 vs. 380.11 +/- 79.94 msec, P=0.002) compared with in the control group. Abnormalities in the endogenous evoked potentials were observed in 36 patients (26.5%). The mean latency time was significantly longer in the treatment groups compared with in the control group (NY: 329.13 +/- 28.07 msec, P=0.001; pBFM: 332.97 +/- 23.97 msec, P<0.001; BFM95: 331.47 +/- 31.05 msec, P<0.001). The reaction time was equally prolonged in both groups. In comparisons between the studied groups and the control group the most significant prolongation was recorded in the NY group (461.8 +/- 140.3 vs. 380.1 +/- 78.04 msec, P=0.039). Significantly higher frequency of prolonged reaction time in non-irradiated patients that received BFM95 was also revealed (21.62 vs. 15.85%, P=0.007). In addition, radiotherapy significantly reduced the P300 wave amplitude (mean values: 10.395 +/- 5.727 vs. 12.739 +/- 6.508 mV, P=0.027). In conclusion, endogenous P300 event-related potentials may be a useful tool in screening of subclinical cognitive changes in ALL survivors.