CA 19-9 is predominantly associated with which cancer type?

CA 19-9 is a tumor marker that is primarily associated with pancreatic cancer. It is a carbohydrate antigen that can be elevated in patients with various malignancies, but its strongest correlation is with pancreatic adenocarcinoma. Elevated levels of CA 19-9 are often used in clinical practice to assist in the diagnosis of pancreatic cancer, to monitor treatment response, and to check for recurrence after treatment.

While CA 19-9 can also be elevated in other conditions such as cholangiocarcinoma, colorectal cancer, and even benign conditions like pancreatitis and liver disease, its specificity and sensitivity for pancreatic cancer make it the most relevant tumor marker in this context. Hence, the association with pancreatic cancer is the strongest and most clinically significant among the options provided.