Googling for "Recurrence after Whipple" (including quotes) will return a ton of hits. You can narrow that down to more academic/scientific results by starting at Google Scholar ( https://scholar.google.com/ ).

From my own (non-medical professional) journey with PC + recurrence, and surveying the landscape on various forums, "symptom" is perhaps not the best thing to look for because symptoms occur so late in the progression of disease. With bile duct blockage and the resulting jaundice being a first symptom of PC for many people, a patient with stents or Whipple surgery may not experience jaundice, and thus not detect a recurrence until other more insidious symptoms emerge at later stages of the disease.

Anyone who has already had pancreatic cancer and surgery to resect it should know something about their CA19-9 history (levels when they were health vs sick, or if their tumors even expressed CA19-9 at all). CA19-9 seems to be the most affordable and easily accessible way to monitor yourself over time. Increases in CA19-9 seem to be the first indication of recurrence for a lot of people (myself included).

If your tumors don't express CA19-9, there may be other affordable blood biomarkers like CEA that could be indicative. Any patient's own history should identify whether that is the case. Other ctDNA/cfDNA tests like Signatera and Galleri can also be used, but are not so affordable, and maybe not as indicative early on as CA19-9 (again, exactly my case).