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Updated: Jun 4, 2026
Unilateral Lung Volume Analysis Using Micro-CT for Enhanced Assessment of Pulmonary Fibrosis in Preclinical Models
Published on: June 20, 2025
CA 15-3 as an alternative marker for KL-6 in fibrotic lung diseases
A Kruit1, W B M Gerritsen, N Pot
1Department of Clinical Chemistry, St Antonius Hospital, Koekoekslaan 1, 3435 CM, Nieuwegein, The Netherlands.
Background:
KL-6 is a mucin that is increased in interstitial lung diseases (ILD), and in some malignancies. CA 15-3, a tumor marker for breast cancer, refers to the same mucin but utilizes antibodies against different epitopes.
Objective:
The aim of our study was to evaluate CA 15-3 as a viable alternative to KL-6 as a for ILDs with and without fibrosis.
Design:
Serum from 242 patients with ILDs and from 327 healthy controls were included and KL-6 and CA 15-3 were measured in all subjects. Regression analyses and ROC curves were used to compare the performances of both markers.
Results:
KL-6 and CA 15-3 levels were both significantly higher in the ILD patients compared to the controls (p < 0.0001). A weak yet significant correlation was found between serum KL-6 and CA 15-3 levels in the controls (R = 0.39, p < 0.0001), but showed a much higher correlation in the patient group (R = 0.85, p < 0.0001). CA 15-3 correlated best with KL-6 in patients with fibrotic ILDs (R = 0.83, p < 0.0001). KL-6 performed better as a marker compared to CA 15-3 in most ILDs. Both markers performed best in identifying idiopathic pulmonary fibrosis (IPF) and were equally able to differentiate between ILDs with and without fibrosis: (sensitivity and specificity %): 100/97, 95/92, and 90/72, respectively.
Conclusion:
CA 15-3 and KL-6 are equally sensitive and specific in terms of differentiating between ILDs with and without fibrosis. The wide availability, ease of use, and cost effectiveness, make CA 15-3 a viable alternative for KL-6 as a possible marker for pulmonary fibrosis.