AbstractBackgroundPrevious trials suggest that older adults with non‐small cell lung cancer (NSCLC) derive benefit from platinum doublet combination therapy, but its superiority is controversial. Although geriatric assessment variables are used to assess the individual risk of severe toxicity and clinical outcomes in older patients, the standard first‐line treatment is still debated. Therefore, we aimed to identify the risk factors for clinical outcomes in older patients with NSCLC.MethodsPatients aged ≥75 years with advanced NSCLC treated at any of 24 National Hospital Organization institutions completed a pre‐first‐line chemotherapy assessment, including patient characteristics, treatment variables, laboratory test values, and geriatric assessment variables. We evaluated whether these variables were the risk factors for progression‐free survival (PFS) and overall survival (OS).ResultsA total of 148 patients with advanced NSCLC were treated with combination therapy (n= 90) or monotherapy (n= 58). Median PFS was 5.3 months and OS was 13.6 months. We identified that hypoalbuminemia (hazard ratio [HR] 2.570, 95% confidence interval [CI]: 1.117–5.913,p= 0.0264) was a risk factor for PFS and monotherapy (HR 1.590, 95% CI: 1.070–2.361,p= 0.0217), lactate dehydrogenase (HR 3.682, 95% CI: 1.013–13.39,p= 0.0478), and high C‐reactive protein (HR 2.038, 95% CI: 1.141–3.642,p= 0.0161) were risk factors for OS. The median OS was significantly longer in patients treated with combination therapy than in those who received monotherapy (16.5 months vs. 10.3 months; HR 0.684, 95% CI: 0.470–0.995,p= 0.0453).DiscussionPlatinum doublet combination therapy may be beneficial in older patients with NSCLC. Identification of risk factors will assist in the development of a personalized treatment strategy.