ABSTRACT
<p><b>OBJECTIVE</b>To study the expression and clinical significance of P-gp, GST-pi and Topo II alpha in gastric and colorectal cancers.</p><p><b>METHODS</b>The expression of P-gp, GST-pi and Topo II alpha in 83 cases with gastric or colorectal cancer were examined by immunohistochemistry S-P.</p><p><b>RESULTS</b>The positive expression rates of P-gp, GST-pi, Topo II alpha in normal tissue and gastric and colorectal cancers were 69.9%, 65.1%, 50.6% and 83.1%, 85.5%, 45.8%, respectively. The positive rates of P-gp and GST-pi in gastric and colorectal cancer were significantly higher than those in normal gastric and colorectal tissue (P < 0.05). The expression of Topo II alpha in poorly differentiated cancers was significantly higher than that in well-and moderately differentiated cancers. There was no correlation between other items and clinicopathological parameters (P > 0.05).</p><p><b>CONCLUSION</b>P-gp, GST-pi and Topo II alpha play important role in multidrug resistance. Their mechanisms of drug resistance were different. The detection of expression of P-gp, GST-pi and Topo II alpha has an important guiding significance in chemotherapy for gastric and colorectal cancers.</p>