MS O12 - HPB The efficacy of CA19-9 in predicting resectability and survival in pancreatic cancer patients with jaundice: A retrospective cohort study

Abstract Background Carbohydrate antigen 19-9 (CA19-9) is the most utilised biochemical marker in pancreatic ductal adenocarcinoma (PDAC); shown to be related to resectability and prognosis. However, concurrent cholestasis, commonly seen in PDAC, can also elevate CA19-9, which may lead to unreliability and hence limit its efficacy in jaundiced patients, making management planning and prognostication more challenging. This study aims to investigate the impact of jaundice on the efficacy of CA19-9 in predicting resectability and survival in PDAC patients. Method 715 patients undergoing attempted resection for PDAC between 2010-2023 were identified from a prospectively maintained surgical database for retrospective analysis. The ability of CA19-9 to predict resectability and survival in different bilirubin sub-groups was assessed using receiver operating characteristic and Kaplan-Meier curves. Existing adjustment methodologies were applied and the curves replotted to assess their effects on the predictive efficacy of CA19-9. Multivariate analysis was then utilised to screen other potentially predictive factors which could be incorporated in the future. Results Of the 554 (77.4%) patients who underwent resection, CA19-9 predicted resectability in the first three bilirubin subgroups: ≤21 µmol/l (AUROC:0.660, 95% CI:0.551-0.769, p=0.004), 21<x≤130 µmol/l (AUROC:0.689, 95% CI:0.595-0.784, p<0.001) and 130<x≤315 µmol/l (AUROC:0.710, 95% CI:0.614-0.807, p<0.001). However, CA19-9 did not predict resectability in patients with bilirubin levels >315 µmol/l (AUROC:0.579, 95% CI:0.452-0.707, p=0.222). CA19-9 was a significant predictor of overall survival in the non-jaundiced (p=0.048) cohort but did not predict survival in patients with bilirubin levels >21 µmol/l. Existing adjustment methodologies did not improve predictive efficacy of CA19-9 for resectability or prognosis. Conclusion These findings support the prospect of decreased ability of CA19-9 to predict resectability and survival in PDAC patients with jaundice. Further investigation is required to find a method of adjusting CA19-9 values based on jaundice to aid diagnostic and treatment decision making.