To determine the predictive value of the expression of p53 and glutathione S-transferase-π (GST-π) with respect to chemotherapy response, immunostaining was performed on transbronchial biopsy specimens from previously untreated patients with non-small cell lung cancer. Of the 54 patients, 34 patients (63%) and 37 patients (69%) were positive for p53 and GST-π, respectively. The response rates in the p53-positive and p53-negative group were 15 and 45%, and those in GST-π-positive and GST-π-negative groups were 16 and 47%, respectively. A multiple logistic regression analysis revealed that positive immunostaining for GST-π was a significant risk factor for clinical chemotherapy resistance. The combination of these two markers was the most important independent factor in predicting a response to chemotherapy in multiple logistic regression analysis. Immunohistochemical expression of p53 and GST-π was independently related to clinical chemoresistance in patients with non-small cell lung cancer. Combined use of these two biomarkers may be a useful predictor of clinical chemoresistance.
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