Can high levels of ca 19-9 in the blood be caused by something other than cancer?

Jaundice. Any type of liver/bile duct obstructions can cause spurious elevations in the ca19-9 levels.
Yes. Apart from cancer, elevated levels may also occur in pancreatitis, cirrhosis, and diseases of the bile ducts. It can be elevated in people with obstruction of the bile ducts. Ca19-9 can be elevated in many types of gastrointestinal cancer, such as colorectal cancer, esophageal cancer and hepatocellular carcinoma.