OBJECTIVETo investigate the expression of multidrug resistance (MDR) gene-associated proteins (MRP) in gastric carcinoma, and their effects on the postoperative adjuvant chemotherapy and the prognosis of patients.

METHODSThe expressions of ToPo II, MRP, GST-pi in 99 patients with gastric carcinoma were detected by immunohistochemistry. The expression and its relationship to the pathological data were analyzed. The positive expression of MRP and GST-pi, and the negative expression of ToPo II were considered as risk factors. Patients were divided into two groups: a high risk drug-resistant group (2-3 risk factors) and the low risk drug-resistant group (0-1 risk factors). Postoperative recurrence, survival rate, and efficacy of adjuvant chemotherapy were compared between two groups.

RESULTSThe positive rate of ToPo II was 74.7%, and the expression was associated with types and differentiation of the tumor. The positive rate of GST-pi was 49.5%, and the expression was related to the gender and the differentiation. The positive rate of MRP was 40.4%, and there was no relationship between the MRP expression and the pathological finding. There were no significant differences in the recurrence, time to recurrence, and the 5-year survival rate between the positive and negative group of the three proteins (P>0.05). Recurrence was found in 25 cases(55.6%) in the high risk drug-resistant group and the mean time to recurrence was (15.2+/-8.1) months. The time to recurrence was shorter in the low risk drug-resistant group [(21.3+/-11.1) months, P<0.05] , but there was no significant difference in the recurrence rate between two groups (P>0.05). The 5-year survival rate of the high risk drug-resistant group and the low risk drug-resistant group was 44.4% and 55.6% (P>0.05). The 5-year survival rates of patients with or without chemotherapy in the high risk drug-resistant group were 45.8% and 42.9% (P>0.05). The 5-year survival rates of patients with or without chemotherapy in the low risk drug-resistant group were 70.4% and 40.7%. The survival rate of patients with chemotherapy was higher than that of the patients without chemotherapy (P<0.05).

CONCLUSIONSThe expression of ToPo II, MRP and GST-pi is associated with the efficacy of postoperative adjuvant chemotherapy. Chemotherapy appears to be more beneficial to patients with low risk drug-resistance.