[Predictive value of drug resistance-related genes expression in neoadjuvant chemotherapy in patients with non-small cell lung cancer of stage III].

Background & Objective: P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), and lung resistant protein (LRP) play important roles in multidrug resistance (MDR). This study was to determine P-gp, MRP, and LRP expression in patients with non-small cell lung cancer (NSCLC) of stage III, and evaluate their predictive value in neoadjuvant chemotherapy.

Methods: Immunohistochemical analyses were performed on 31 patients with NSCLC of stage III before, and after neoadjuvant chemotherapy.

Results: The frequency of P-gp, MRP, and LRP expression were 29.0% (9/31), 45.2% (14/31), and 38.7% (12/31) before chemotherapy, and were 61.3% (19/31), 51.6% (16/31), and 41.9% (13/31) after chemotherapy. Of 31 patients, 10 (10/31, 32.3%) expressed both MRP and LRP before chemotherapy, which indicated significant positive correlation between MRP and LRP expression (r=0.061, P< 0.001). In patients with P-gp, MRP, or LRP expression before chemotherapy, the response rates towards chemotherapy were 44.4% (4/9), 28.6% (4/14), and 16.7% (2/12). Of 10 patients with both MRP and LRP expression, only 1 (1/10, 10.0%) responded to chemotherapy. The median survival time of patients who responded to chemotherapy was 31 months, while that of patients who did not responded to chemotherapy was 15 months, that of patients who didn't receive neoadjuvant chemotherapy before surgery was 18 months.

Conclusion: Patients with both MRP and LRP expression are probably resistant to chemotherapy, the value of neoadjuvant chemotherapy is limit in such patients.