Factors affecting the association between overall survival and progression-free survival in clinical trials of first-line treatment for patients with advanced non-small cell lung cancer.

PURPOSE: New treatment strategies, particularly the introduction of molecular-targeted agents and appropriate patient selection based on histology and/or genotyping, have progressed markedly in recent years, and the overall survival (OS) in advanced non-small cell lung cancer (NSCLC) patients has improved. The aim of the study was to identify factors affecting longer OS than that estimated from progression-free survival (PFS) in first-line treatment for advanced NSCLC.

METHODS: Sixty-five controlled trials for first-line treatment of advanced NSCLC were extracted for the study. Factors influencing higher than predicted OS were examined by logistic regression analysis between the OS-extended group and the OS-association group.

RESULTS: PFS was moderately associated with OS. Twenty arms of 14 trials were categorized as an OS-extended group, in which the ratio of observed OS to estimated OS was found to be over 1.2. On multivariate logistic regression analysis, number of patients lower than 150, average age younger than 63 years, and percentage of squamous carcinoma <30 % were found to significantly affect this relationship.

CONCLUSION: We identified number of patients and well-known prognostic factors including age and histological cancer type as factors influencing longer OS. These factors should be considered for patient eligibility, when PFS is used as a surrogate primary endpoint for OS in randomized clinical trials of first-line treatment for patients with advanced NSCLC.