Magnetic Resonance-Guided Radiotherapy for Unresectable Hepatocellular Carcinoma with Bile Duct Tumor Thrombus: A Case Series and Review of Treatment Options.

Bile duct tumor thrombus (BDTT) is a rare manifestation of hepatocellular carcinoma (HCC) that causes obstructive jaundice and is associated with a poor prognosis, although a treatment algorithm has yet to be established. We review the treatment landscape for HCC with BDTT, including surgical, transarterial, systemic, and radiotherapy options, and report, to our knowledge, the first case series of magnetic resonance-guided radiotherapy (MRgRT) for this condition. Four patients with unresectable HCC and BDTT were treated on a 0.35-T MR-linac with real-time cine-MRI gating (50 Gy in 5 fractions, n = 3; 40 Gy in 5 fractions, n = 1), with tumor response assessed by modified RECIST. All patients completed treatment without interruption. The best response was complete response in two patients and partial response in two, and obstructive jaundice resolved in both affected patients. The maximum radiation-attributed toxicity was a transient grade 3 bilirubin elevation that resolved without biliary intervention, and no treatment-related deaths occurred. Overall survival ranged from 5.5 to 29 months, with the two Child-Pugh class A patients without portal vein tumor thrombosis surviving 22 and 29 months. MRgRT for HCC with BDTT appears feasible with acceptable short-term safety and merits prospective evaluation.