In the overall population, the median serum KL-6 level (U/mL) was higher among patients who developed ILD (n = 865) than among those without ILD (n = 432) (600.7 vs. 326.7; p < 0.001) and higher among patients without lung cancer (n = 875) than among those with lung cancer (n = 422) (556.5 vs. 369.3; p < 0.001) (see Supplementary Fig. S1a–b online). Here, MUC1 is linked to interstitial lung disease.