Survival prediction for patients with ICC undergoing chemotherapy: comparing tumor markers to cross-sectional imaging

Purpose:

Carbohydrate-antigen 19 – 9 (CA19 – 9) has been established as the main serum marker for patients with intrahepatic cholangiocarcinoma (ICC). The aim of this study was to compare the prognostic value of CA19 – 9 changes versus response determined by cross-sectional imaging in patients with ICC undergoing chemotherapy.

Methods and materials:

Between 2003 – 2018, 151 patients with histopathologically-confirmed ICC underwent chemotherapy at our tertiary care center for non-resectable or recurrent ICC, of whom 121 patients were included in this study. CA19 – 9 serum levels and imaging were retrospectively evaluated during chemotherapy. Log-rank testing and optimal stratification was used to classify patients into risk groups.

Results:

Prior to chemotherapy, baseline CA19 – 9 serum levels above the previously published cut-off of 37 U/ml were associated with poor survival (median OS 8.7 vs. 12.4 months, p = 0.003). After beginning of chemotherapy, an increase in CA19 – 9 of more than 40 U/ml resulted in impaired residual survival (median OS 5.0 vs. 12.1 months, p = 0.001). However, progressive disease at the first follow-up imaging proved the strongest predictor for poor outcome (median OS 4.6 vs. 15.5 months, p < 0.001).

Moreover, an increase of CA19 – 9 of more than 55 U/ml resulted in a positive predictive value for progressive disease in imaging of 76%, whereas a decrease in CA19 – 9 of more than 2 U/ml resulted in a negative predictive value for progressive disease of 91%.

Conclusion:

While an increase in CA19 – 9 serum levels during chemotherapy was an even better predictor than baseline CA19 – 9 levels for survival, response evaluation by cross-sectional imaging showed the best predictive performance towards residual OS in our cohort.