Pancreatic ductal adenocarcinoma (PDAC) is a relatively common malignant tumor, and the serum carbohydrate antigen (CA)19-9 is the most commonly used tumor marker in the diagnosis and treatment of PDAC. Elevated levels of CA19-9 in the serum are of significant importance in the diagnosis of most PDAC; however, some PDAC cases may exhibit negative expression of this serum antigen during the disease course. This article reviews recent clinical studies related to PDAC with negative CA19-9 expression, aiming to explore more diagnostic and therapeutic approaches for patients with CA19-9 negative PDAC.

Pancreatic ductal adenocarcinoma (PDAC) is a relatively common malignant tumor, and the serum carbohydrate antigen (CA)19-9 is the most commonly used tumor marker in the diagnosis and treatment of PDAC. Elevated levels of CA19-9 in the serum are of significant importance in the diagnosis of most PDAC; however, some PDAC cases may exhibit negative expression of this serum antigen during the disease course. This article reviews recent clinical studies related to PDAC with negative CA19-9 expression, aiming to explore more diagnostic and therapeutic approaches for patients with CA19-9 negative PDAC.