Shanxi Province Cancer Hospital

The relative activity of multidrug resistance P-glycoprotein in the plasma of breast cancer patients was investigated, the expression of P-glycoprotein before and after chemotherapy was analyzed and its clin. value was evaluated.The plasma of patients and chem. reagents were mixed and distributed into the 96-well plate.The plate was read at 340 nm absorbance before and after reaction.The variation of absorbance for each well was calculated, and then relative activity of each sample was compared to the referent compound activity.The relative activity of over 30% was taken as pos. expression of the P-gp for each sample.The frequency of P-glycoprotein expression was significantly increased from 16.2% before chemotherapy to 43.2% after chemotherapy (P<0.05).The pos. expressions of P-glycoprotein before and after chemotherapy were 5/6 and 9/16, resp., in patients with pos. lymph node metastasis, and 1/6 and 7/16, resp., in patients with neg. lymph node metastasis.The results of this preliminary study suggest in P-glycoprotein expression in plasma of patients play an important role in the selection of drugs, which may be useful to evaluate the prognosis for treatment of breast cancer patients.