Incremental value of volumetric multiparametric MRI over Fudan score for prognosis of unresectable intrahepatic cholangiocarcinoma treated with systemic chemotherapy.

ABSTRACT

BACKGROUND: Individualized patient care requires prognostic models customized to a tumor and an individual's disease profile for reliable survival prediction. MRI has prognostic value for intrahepatic cholangiocarcinoma (ICCA). Existing prognostic models for ICCA exclude imaging-based information about an individual's tumor that may reflect important aspects of tumor's biology. Fudan score, a prognostic model applicable to unresectable ICCA, is limited by subjective morphologic imaging parameters. OBJECTIVES: To assess the prognostic value of baseline volumetric multiparametric MRI in unresectable intrahepatic cholangiocarcinoma (ICCA) treated with systemic chemotherapy and the incremental value of MRI over the Fudan score. METHODS: This retrospective study included 114 ICCA patients treated with systemic chemotherapy between 2007 and 2021 after a baseline MRI. The single largest tumor was volumetrically assessed for anatomic (total tumor volume and diameter) and functional parameters (viable tumor volume, percentage-viable tumor volume, viable tumor burden, and ADC). A derivation cohort of 30 patients was utilized to identify MRI parameters associated with overall survival (OS) using Cox regression analysis. The incremental value of MRI over Fudan score was assessed on an independent sub-cohort of 84 patients using Kaplan-Meier analysis and C-index. RESULTS: 114 patients (64 years +/- 11; 61 women) were evaluated. Pre-treatment high (>1350x10-6 mm2/sec) ADC was the only independent predictor of OS (HR, 8.07; P < 0.001). Replacing subjective tumor boundary with objective ADC value, and using modified biochemical thresholds increased the prognostic stratification for the risk groups in the modified ADC-Fudan model compared to the original Fudan model (median survival 12 and 4.5 months; P = 0.055; vs. 11 and 3 months; P < 0.001). The modified ADC-Fudan model demonstrated an 11 % improvement over the original Fudan model (c-index 0.80 vs. 0.69; P = 0.044) for survival prediction. CONCLUSIONS: High pre-treatment volumetric ADC was associated with unfavorable prognosis in patients with unresectable intrahepatic cholangiocarcinoma treated with systemic chemotherapy. Supplementing the original Fudan model with ADC and modified serum marker thresholds improved the survival prediction performance by 11% in the resulting modified ADC-Fudan model. CLINICAL IMPACT Volumetric MRI could improve the survival prediction among ICCA patients prior to receiving potentially toxic and expensive palliative chemotherapies. This could potentially guide individualized therapy for this patient cohort.