GGTLC1 and cancer: Furthermore, gamma glutamyl transpeptidase (GGT) levels were substantially elevated in the pancreatic cancer group, with a median value of 192.5 U/L compared to 53.5 U/L in the cancer-free group, with an IQR of 102–1681 U/L vs. 20–73 U/L, respectively (p = 0.01).