Survival and prognostic factors of lung cancer patients with preexisting connective tissue disease: a retrospective cohort study

BACKGROUND: Connective tissue diseases (CTDs) are a group of special commodities in lung cancer (LC). This study aimed to analyze the survival and prognostic factors of LC patients with preexisting CTDs. METHODS: A total of 84 LC patients with preexisting CTDs that presented at Peking Union Medical College Hospital (PUMCH) were retrospectively recruited in this study between January 2000 and June 2017. Patient survival was compared using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazard models were used to assess prognostic variables. RESULTS: Of the 84 LC patients, 36 (41.8%) had underlying rheumatoid arthritis (RA), 20 (23.8%) had idiopathic inflammatory myopathy (IIM), 18 (21.4%) had Sjögren syndrome (SS), 6 (7.1%) had systemic sclerosis (SSc), and 4 (4.8%) had systemic lupus erythematosus (SLE). The median overall survival (OS) was 21 months (IQR, 8–72 months), and the 1-, 3-, and 5-year survival rates were 61.3%, 36.7%, and 29.5%, respectively. The survival rates between different CTD subgroups, histopathologies, and disease stages were significantly different (P<0.05). Multivariate analysis showed that the independent prognostic factors for OS were IIM [hazard ratio (HR), 3.61; 95% confidence intervals (CI), 1.69–8.21; P=0.002], SS (HR, 2.72; 95% CI, 1.01–7.33; P=0.048), and radical resection (HR, 0.11; 95% CI, 0.04–0.35; P<0.001). CONCLUSIONS: Different CTD subtypes and the radical resection of LC are closely related to patient prognosis. This indicates a need for both identifications of CTD types and active treatment strategies for LC.