CEACAM5 and cyst: In clinical practice, MRI and CT scans, cytological examination of cyst fluid, measurement of tumor markers such as carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9), and analysis of GTPase Kras (KRAS) and guanine nucleotide-binding protein alpha subunit (GNAS) mutations are used to categorize patients with pancreatic cysts [6, 7, 10–16].