Correlation of carbohydrate antigen 19-9 response with radiologic response and survival in intrahepatic cholangiocarcinoma: A prospective cohort study.

Abstract

51 Background: Although Carbohydrate antigen 19-9 (CA19-9) showed promising prognostic value in patients with intrahepatic cholangiocarcinoma (iCCA), its role in response assessment remains unknown. We aimed to study the association of CA19-9 response (defined as > 50% reduction from baseline) with radiologic response, and its role in predicting outcome in patients with unresectable iCCA. Methods: A prospective cohort of 422 patients who were initially identified as unresectable iCCAs with baseline CA19-9 ≥ 100 U/mL and treated with systemic therapies at our institution between January 2017 and December 2021 was enrolled in this study. Radiologic response was assessed using the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 criteria. A landmark assessment of CA19-9 response and radiologic response was made. The association between CA19-9 response and imaging response, progression-free survival (PFS), or overall survival (OS) were analyzed, respectively. Results: Two hundred and sixty-seven (63.3%) patients showed CA19-9 response. CA19-9 response was seen in 93.2% (123/132) of radiologic responders, and 49.7% (144/290) of radiologic non-responders, respectively (P < 0.001). CA19-9 responders outperformed non-responders in median PFS (10.6 vs 3.6 months, P < 0.001) or OS (21.4 vs 6.3 months, P < 0.001), respectively. The common independent predictors of both OS and PFS included distant metastasis, CA19-9 non-responder, and radiologic non-responder in multivariable analysis. Conclusions: CA19-9 response is a valuable addition to assess tumor response and associated with improved outcome of iCCAs. Achieving CA19-9 response should be one of the therapeutic aims of patients with iCCA who are managed with systemic therapies. The results of this study have first published online in Cancer 2023 Jul 14. doi: 10.1002/cncr.34854 .