MUC1 and interstitial lung disease: However, a study by Miyazaki et al. [44] on 273 LC patients with and without ILD reported that KL-6 levels were higher in the ILD group, but no significant difference was observed in prognosis based on KL-6 levels; this could be due to the low cutoff value (500 U/mL) and small sample size (n = 68).