Can abdominal/pelvic ct scan w/contrast miss a pancreatic cancer?? is this possible?

It is possible: Pancreatic cancer can begin in various locations(head, body or tail of the pancreas) and can be quite small yet cause lots of symptoms. So despite CECT there is small chance of missing this tumor unless the focus of the CT is on the Pancreas and the test is planned and done with this diagnosis in mind. In fact there are special protocols for making this diagnosis.That may not have been done here.