Identifying Subsequent Therapies in Patients with Advanced Non-Small Cell Lung Cancer and Factors Associated with Overall Survival

Study ObjectivesTo identify subsequent therapies used after first-line therapies in patients with advanced non-small cell lung cancer (NSCLC), compare overall survival (OS) associated with subsequent therapies, and evaluate factors associated with OS in these patients. MethodsThe study was a retrospective cohort analysis of patients with advanced NSCLC (stage IIIB/IV) who were initiated on first-line therapy from January 1, 2008, through September 30, 2013, and afterward given subsequent chemotherapy (index date). Patients had to be 18 years or older at the time of diagnosis of advanced NSCLC. Patients were followed from the index date until one of the following end points: end of the study (September 30, 2014), disenrollment from the health plan, or deathwhichever came the earliest. The primary outcome was OS. Kaplan-Meier curves and Cox proportional hazard models were used to analyze OS and evaluate the factors associated with OS. ResultsThe analysis included 1280 patients on subsequent therapies. The most common subsequent therapies were pemetrexed (284 patients [22%]), erlotinib (216 patients [17%]), and docetaxel (139 patients [11%]). Patients from the singlets group had a lower OS at 6.3 months compared with all other groups: pemetrexed based, combination of pemetrexed and bevacizumab based, bevacizumab based, doublets, and tyrosine kinase inhibitors (p<0.0001). Factors associated with greater OS included age younger than 65 years, female gender, and a longer time between initiation of first and subsequent therapies. Factors associated with a reduction in OS were pemetrexed-based or singlet regimens for subsequent therapy, diagnosis of squamous histology, and a higher number of adverse events prior to subsequent therapy. ConclusionWe found that a subsequent therapy consisting of singlets is associated with reduced OS compared with other chemotherapy groups. Patient characteristics such as female gender, age younger than 65 years, diagnosis of nonsquamous histology, and/or a longer time frame between initiation of first-line and subsequent chemotherapy are associated with longer survival.