Tumor sensitivity to anticancer drugs such as CPT-11 and platinum derivatives was investigated by assessing Topo-1 and Bax/ERCC-1 expression in patients with stage I/II breast, lung, and gastric cancer who were positive for ONCs, and tumor sensitivity was compared between CPT-11 and platinum derivatives. In the recurrence group (RG) (n=5), immunohistochemistry revealed high expression of Topo-1 in 3 patients (60%) and low expression in 2 patients (40%), while the non-recurrence group (N-RG) (n=17) showed high Topo-1 expression in 3 patients (17.6%) and low expression in 14 patients (82.4%) (not significant; N.S.). High Bax expression combined with low ERCC-1 expression was observed in 2 patients (40%) from the RG and other patterns of expression were seen in 3 patients (60%), while high Bax/low ERCC-1 expression was observed in 3 patients (17.6%) from the N-RG and other patterns were found in 14 patients (82.4%) (N.S.). PCR analysis of Topo-1 expression in the RG (n=4) revealed high expression in 4 patients (100%), while the N-RG (n=5) showed high expression in 3 patients (60%) and low expression in 2 patients (40%) (N.S.). With respect to ERCC-1, PCR analysis of the RG (n=4) also revealed high expression in 4 patients (100%), while the N-RG (n=5) again showed high expression in 3 patients (60%) and low expression in 2 patients (40%) (N.S.). There were significant differences between the expression of high Topo-1 and low ERCC-1 in the RG (p<0.01). These results suggest that tumor sensitivity to CPT-11 may be higher than that for platinum derivatives in patients with node-negative stage I/II breast, lung, or gastric cancer who are positive for ONCs.

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