Serum carcinoembryonic antigen levels correlate with disease severity and 1-year survival across different interstitial lung diseases subtypes

OBJECTIVES: Tumour markers may correlate with interstitial lung disease (ILD). We conducted a large, population-based retrospective study to investigate the relationship between serum carcinoembryonic antigen (CEA) levels and disease severity and 1-year mortality in different ILD subtypes. METHODS: ILD patients treated at Nanjing Drum Tower Hospital from 2014 to 2022 were included. The primary end point was 1-year mortality. Cox regression and receiver operating characteristic analyses were used to identify independent risk factors and determine the optimal CEA cut-off. RESULTS: Overall, 1209 ILD patients were enrolled. Serum CEA levels correlated with the composite physiological index (CPI) in idiopathic pulmonary fibrosis (IPF) (r = 0.170, P = 0.007), idiopathic inflammatory myopathy-associated ILD (IIM-ILD) (r = 0.222, P < 0.001), primary SS-associated ILD (pSS-ILD) (r = 0.179, P < 0.001) and undifferentiated connective tissue disease-associated ILD (r = 0.146, P = 0.042). Subgroup analysis showed higher CEA in acute exacerbations of IPF [5.44 vs 2.49 ng/ml, P = 0.009], anti-melanoma differentiation-associated gene 5-positive IIM-ILD [3.62 vs 1.47 ng/ml, P < 0.001] and rapidly progressive IIM-ILD [4.88 vs 1.48 ng/ml, P < 0.001]. After adjustment for age, sex, smoking history and CPI, elevated CEA was independently associated with increased 1-year mortality in IPF (HR 1.118; 95% CI 1.031-1.212; P = 0.007), IIM-ILD (HR 1.225; 95% CI 1.160-1.293; P < 0.001) and pSS-ILD (HR 1.295; 95% CI 1.091-1.538; P = 0.003). Moreover, CEA ≥2.835 ng/ml was associated with increased 1-year mortality in IPF (HR 3.230; 95% CI 1.492-6.994; P = 0.003) and IIM-ILD (HR 13.022; 95% CI 5.272-32.165; P < 0.001). CONCLUSIONS: Serum CEA levels are associated with disease severity and 1-year mortality across ILD subtypes, supporting its potential as a reliable prognostic biomarker.