CEACAM5 and interstitial lung disease: Our group investigated serum tumor marker levels in ILD and found that serum CEA and CA125 levels were significantly higher in ILD patients than in patients with other lung diseases such as chronic obstructive pulmonary diseases, pneumonia, bronchial asthma, and ILD patients with elevated serum CEA and CA125 levels showed higher risk of cancer, indicating that serum CEA and CA125 levels may be a marker of cancer in ILD patients [14].