Importance of carbohydrate antigen (CA 19-9) and carcinoembrionic antigen (CEA) in the prognosis of patients with duodenal adenocarcinoma: a retrospective single-institution cohort study

Background: Duodenal adenocarcinoma (DA) is a rare malignancy without validated tumor markers. In practice, carcinoembryonic antigen (CEA) and carbohydrate antigen (CA 19-9) are often used in the management of DA, though their prognostic value is unknown. Materials and Methods: A single-institution retrospective review included patients diagnosed with biopsy-confirmed adenocarcinoma of the duodenum between 2006 and 2021. Peri-ampullary tumors were excluded. Levels of CA 19-9 and CEA were collected as continuous variables and were analyzed as binary variables: normal vs. high, using the maximum normal value as a cut-off (normal Ca 19-9 <35 U/ml; CEA <3 ng/ml). Survival analysis was conducted using Kaplan Meier curves, log-rank test and Cox proportional hazards model. Results: There were 68 patients included in the final analysis. Median age was 67 years old and median follow-up time was 22.2 months. CA 19-9 and CEA were elevated in 36.8% and 48.5% of patients, respectively. A concomitant elevation of both tumor markers was associated with worsened OS (HR 2.140, 95% CI: 1.114–4.112; p = 0.019). After controlling for age and sex on multivariate analysis, elevation in both CA 19-9 ≥35 and CEA ≥3.0 remained significantly associated with increased mortality (HR 2.278, 95% CI: 1.162–4.466; p = 0.016). Conclusions: In summary, CA 19-9 and, to a lesser extent, CEA, show promise as prognostic markers in DA. Larger studies are needed to validate their use and to evaluate their performance as markers of recurrence.