CA19-9 has never been used as a stand-alone diagnostic test because of a number of pathologies and inflammation causing its elevation. If you have an elevated CA19-9:and acinar, it is likely you have a mixed tumor type with ductal adenocarcinoma. I know of a couple of instances where mixed tumor types were missed on initial morphological examination and when sent to MSKCC for a second review, PDAC was found and the diagnosis changed to mixed PACC and PDAC explaining the presence of an elevated CA19-9.

In those that express CA19-9 with the PDAC form, it can be useful to monitor efficacy of treatment by observing its trend of values. No single point is of value in making a conclusion. It requires several successive measurements.