CTSB and esophageal cancer: In a similar approach, Yan et al. (2017) measured cystatin C and cathepsin B levels in serum from 56 esophageal cancer patients and found values of 703.96 +/− 23.6 ng/ml for cystatin C and values of 38.35 +/− 4.3 ng/ml for cathepsin B in disease subjects and related these values to lymph node metastasis.