MUC1 and interstitial lung disease: In conclusion, we evaluated the association between clinical values of KL-6, tumor markers, and ILD in patients with pSS and found that KL-6 and tumor markers such as CEA, CA153, and CA125 in patients with pSS-ILD were higher than that in patients with non-ILD, but KL-6 was more statistically significant and could be used to identify ILD development in patients with pSS.