CA 19-9 serum levels in patients with end-stage idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases (ILDs): Correlation with functional decline

Idiopathic pulmonary fibrosis presents a progressive and heterogeneous functional decline. CA 19-9 has been proposed as biomarker to predict disease course, but its role remains unclear. We assessed CA 19-9 levels and clinical data in end-stage ILD patients (48 IPF and 20 non-IPF ILD) evaluated for lung transplant, to correlate these levels with functional decline. Patients were categorized based on their rate of functional decline as slow (n = 20; ΔFVC%pred ≤ 10%/year) or rapid progressors (n = 28; ΔFVC%pred ≥ 10%/year). Nearly half of the entire patients (n = 32; 47%) had CA 19-9 levels ≥37kU/L. CA 19-9 levels in IPF were not different from non-IPF ILD populations, however, the latter group had a median CA 19-9 level above the normal cut-off value of 37 KU/l (60 [17-247] kU/L). Among IPF patients, CA 19-9 was higher in slow than in rapid progressors with a trend toward significance (33vs17kU/L; p = 0.055). In the whole population, CA19-9 levels were inversely related with ΔFVC/year (r = -0.261; p = 0.03), this correlation remained in IPF patients, particularly in rapid progressors (r = -0.51; p = 0.005), but not in non. Moreover, IPF rapid progressors with normal CA 19-9 levels showed the greater ΔFVC/year compared to those with abnormal CA 19-9 (0.95 vs. 0.65 L/year; p = 0.03). In patients with end-stage ILD, CA 19-9 may represent a marker of disease severity, whereas its level is inversely correlated with functional decline, particularly among IPF rapid progressors.