MUC1 and neoplasm: In addition, we performed immunohistochemical staining of paired primary tumor and lung metastasis tissue sections from the same patient and found that PDL1 levels were higher in lung metastases than in primary tumors, and that MUC1 was positively correlated with PDL1 (r = 0.3919, P = 0.0219) (Fig. 5f-h).