Organ-specific variations in tumor marker dynamics in postoperative pancreatic cancer recurrence: Trends in lung and liver recurrence highlighting biological heterogeneity.

Background/objectives: Although tumor recurrence after surgical resection in pancreatic cancer (PC) is generally considered incurable, it is well-accepted that clinical presentations and outcomes vary according to the recurrent sites (e.g., liver vs. lung recurrence), suggesting a possible biological inhomogeneity of PC recurrence. Understanding the behavior of biological factors, specifically tumor markers (TMs), at different recurrence sites may contribute to individualized treatment strategies. Therefore, this study aimed to compare the dynamics of pre-recurrence TMs at liver and lung recurrence sites.

Methods: Patients with isolated postoperative liver or lung recurrence as their first recurrence were enrolled. Starting from the recurrence date confirmed by imaging examinations, the values of TMs (carbohydrate antigen 19-9: CA19-9; carcinoembryonic antigen: CEA) were retrospectively evaluated 6 and 3 months before recurrence and at the time of recurrence.

Results: Patients with liver recurrence displayed a significant increase in CA19-9 and CEA levels from as early as 6 months before recurrence. Contrastingly, patients with lung recurrence demonstrated a significant elevation of CA19-9 levels starting from 3 months before recurrence, with no increase in CEA levels, even at the time of recurrence. The relative change in CA19-9 and CEA levels during each period were significantly lower in patients with lung recurrence.

Conclusions: Both TMs exhibited organ-specific variations in patients with postoperative PC recurrence. This disparity may reflect the biological heterogeneity of PC between recurrence patterns, thereby highlighting the importance of conducting postoperative follow-up with consideration of this fact.