Expression of CA 72-4 (TAG-72) in the fluid contents of pancreatic cysts: A new marker to distinguish malignant pancreatic cystic tumors from benign neoplasms and pseudocysts

Objective: The authors evaluated cyst fluid CA 72-4 as a tumor marker in the differential diagnosis of pancreatic cystic lesions. Summary Background Data: Pancreatic cystic lesions include inflammatory pseudocysts, serous cystadenomas, and mucinous tumors. Mucinous tumors can be further subdivided into mucinous cystadenocarcinomas and premalignant mucinous cystic neoplasms. The clinical and radiologic features of these lesions are unreliable to make a preoperative diagnosis of these diagnostically difficult lesions. Analysis of aspirated cyst fluid was proposed as an aid to making the preoperative differential diagnosis. Currently, a number of parameters have been reported as useful markers in cyst fluid aspirates, including the tumor markers carcinoembryonic antigen and CA 15.3, enzymes (amylase, lipase, and amylase isoenzymes), relative viscosity, and cytologic analysis. However, owing to the rarity of pancreatic cystic tumors, experience with cyst fluid analysis is limited. To define additional markers that might be useful in the differential diagnosis of pancreatic cysts, the authors measured the tumor- associated glycoprotein 72 (TAG-72) in aspirates from 19 pancreatic cystic lesions. Methods: Cyst fluid from 19 pancreatic cysts was obtained by needle aspiration. The tumor marker TAG72 was measured by a commercial (CA 72-4) immunoassay. Results: Cyst fluid CA 72-4 levels in mucinous cystadenocarcinomas were markedly elevated (mean, 10,027 U/mL; range, 780 to 34,853 U/mL) compared with that in pseudocysts (mean, 3.8 U/mL; range, < 3 to 5.7 U/mL) and serous cystadenomas (mean and range, < 3 U/mL; p < 0.001). The level of CA 72-4 in benign mucinous cystic neoplasms was intermediate (mean, 44.2 U/mL; range, < 3 to 137 U/mL), but it was statistically different from either carcinomas (p = 0.009) or benign cysts (p < 0.001). Conclusions: CA 72-4 in cyst fluid aspirates is a promising new marker for the differentiation of mucinous cystadenocarcinoma from pseudocysts, serous cystadenomas, and mucinous cystic neoplasms. Intermediate values are associated with benign mucinous cystic neoplasms.