In our study, we found that serum KL-6 level and tumor markers (CEA, CA125, CA153) were significantly higher in patients with pSS-ILD than in those with non-ILD as well as healthy controls, but multivariate analysis KL-6 was more abnormally increased and could be used to identify ILD development in patients with pSS. The gene discussed is MUC1; the disease is neoplasm.