RIA of plasma GST-π and its diagnostic significance in breast tumor

Antibodies prepared against GST-pi were labeled with (125)l and then RIA of plasma GST-pi was established with high specificity sensitivity and accuracy. Using the RIA established, plasma GST-pi levels of 135 normal women, 94 benign breast disease and 165 breast cancer patients were measured. The pre- and post-operation, chemotherapy and radiotherapy of plasma GST-pi levels of 55, 53 and 20 of the breast cancer patients were also measured. The average plasma GST-pi concentrations of healthy women, benign breast diseases and breast cancer patients were 4.89+/-1.43 mu g/L (3.68%), 5.78+/-2.67 mu g/L (8.04%) and 10.25+/-4.03 mu g/L (65.62% positive) respectively, (P<0.01). Cut-off value of plasma GST-pi concentration was 9.48 mu g/L and the false positive rate was 3.68%. The plasma GST-pi concentrations of patients before and after operation were 10.00+/-3.02 mu g/L and 6.69+/-2.05 mu g/L respectively (P<0.01); and the positive rate were 60% and 20% (P<0.01). The plasma level of GST-pi of pre- and post- chemo- and radio-therapy were 10.85+/-4.59 and 10.52+/-3.96, 8.74+/-2.43 and 5.62+/-2.56 respectively. The results suggested that GST-pi may be used as a tumor marker for breast cancer diagnosis.