Objective:To identify the influence of comorbidity on the choice of treatment and survival of elderly patients (≥70 years) with advanced non-small cell lung cancer (NSCLC).Methods:The clinical characteristics and the choices of treatment of 177 elderly patients,who had a good performance status (PS＜1) were retrospectively analyzed in Oncology Department,Shanghai Pulmonary Hospital,between January 2005 to December 2005.Survival data were only analyzed in those whose had received chemotherapy.All patients were stratified by number of comorbidity as none (0),mild (1-2) and severe (≥3) groups.Results:The proportion of patients,who received chemotherapy,with none,mild and severe comorbidity was significantly different (79.3%,76.2% and 57.4%,P＝0.038),and there was also significantly different about palliative radiotherapy rate among the three groups (21 1%,11.7% and 37.0%,P＝0.014).The median survival and 1-year survival rate in none,mild and severe comorbidity groups,were 13.6 vs.10.2 vs.7.6 months and 53.5% vs.41.3% vs.20.8% respectively (Log-rank,P＝0.071).In univadate and multivariate Cox models analysis,only severe comorbidity was a independent hazard factor of survival of elderly patients with NSCLC.Relative ratio (RR,95% Cl):(2.09,1.06-4.15),P＝0.034.Conclusion:Comorbidity may affect the choice of treatment of elderly patients with advanced NSCLC slightly,but only severe comorbidity is a independent prognostic factor of survival.