CEACAM5 and interstitial lung disease: Recent studies have confirmed that the level of serum tumor markers is dramatically higher in connective tissue disease patients with ILD, which has been used as a predictor for ILD onset and deterioration.[33,34] Studies have shown that the serum levels of CA125, CEA, and CA153 were elevated in the pSS-ILD.[35] CA19-9 can be used as a biomarker for lung disease severity in patients with end-stage ILD.