[Establishment of a model to assess the clinical efficacy of Gefitinib in treatment of non-small cell lung cancer].

Objective: To establish a model to predict the clinical response of Gefitinib in non-small cell lung cancer (NSCLC).

Methods: The clinical outcomes of 262 consecutive advanced NSCLC patients to oral treatment of gefitinib 250 mg daily in the past 4 years were reviewed. DNA sequencing was used to detect the mutations in the exons 18, 19, 20, and 21 of the epidermal growth factor receptor (EGFR) tyrosine kinase domain in 55 patients who had enough tumor tissues.

Results: The response rate and disease control rate of gefitinib in the advanced NSCLC patients were 30.1% and 78.6% respectively. The median progression free survival and median overall survival were 6.0 and 16.0 months respectively, while the 1, 2 and 3-year survival rates of the NSCLC patients were 60.8%, 35.6%, and 18.3% respectively. The clinical response rate of the patients with EGFR mutation was 50.0%, significantly higher than that of those patients without mutation (16.1%; P = 0.009). In the majority of patients Gefitinib was well tolerated, and the common adverse effects were skin rash and diarrhea. Based on the results of our patients, we try to establish a model which may predict the response of patients by logistic multivariate regression analysis. Patients being female aged under 65, with adenocarcinoma, not smoking, taxone-unresistant and with EGFR mutation were more sensitive to gifitinib. However, COX multivariate regression analysis showed that only the age, histology, smoke status and EGFR mutation were valuable in selection of sensitive patients. So, we set up the cut-off value at 2 in the model based on these 4 factors. The response rate of the patients with 2 or more scores was 34.2%, significantly higher than that of the patients with the scores < 2 (9.3%, P = 0.001). The sensitivity would be doubled when the score increases by one point.

Conclusion: A simple clinical model based on the patients' age, histology, smoking status and EGFR mutation has been established and is useful to determine the efficacy of gifitinib in NSCLC patients.