Gene expression levels of APTX ( P < 0.001), BRCA1 ( P < 0.001) and ERCC1 ( P < 0.001) were significantly lower in irinotecan-sensitive patients than in irinotecan-resistant patients, while ISG15 ( P = 0.047) and Topo1 ( P = 0.002) were significantly higher. Box plots showed the mRNA expression levels of APTX (A), BRCA1 (B), ERCC1 (C), ISG15 (D) and Topo1 (E) in irinotecan-sensitive and irinotecan-resistant groups, respectively (n = 100). The lines inside the boxes denoted the medians. The whiskers of box plots: Min to Max. Graphs of ROC curve showed the AUCs of APTX (F), BRCA1 (G), ERCC1 (H), ISG15 (I) and Topo1 (J) for predicting irinotecan sensitivity. Sensitivity (Y-axis) was plotted against false-positive fraction (1 - specificity).