Dynamic Prediction Model for Patients with Unresectable Biliary Malignancies Receiving Systemic Chemotherapy Combined with Immunotherapy: a Multicenter, Observational Study

Inclusion Criteria: * 1\. Confirmed by histopathological diagnosis and/or clinical diagnosis (typical imaging features, clinical manifestations, laboratory examination, etc.) as biliary malignancy (Chinese Society of Clinical Oncology (CSCO) Guidelines for Diagnosis and Treatment of Biliary malignancy (2024)); 2. Based on unresectable malignant tumor in the diagnosis of biliary and in patients undergoing chemotherapy with immunosuppressant therapy system; 3. The liver function class for Child - Pugh, A or B; 4. More than 18 years of age, gender not limited; 5. Expected survival time for 3 months or more; 6. ECOG PS score 2 or less; 7. Meet the following laboratory test parameters: 1. Hematological system function: Absolute neutrophil count ≥ 1.0×10⁹/L; platelet count ≥ 50×10⁹/L; hemoglobin ≥ 90 g/L; international normalized ratio less than 1.7 or prothrombin time prolongation not exceeding 4 seconds. 2. Liver function: Alanine aminotransferase/aspartate aminotransferase not exceeding 5 times the upper limit of normal; total bilirubin ≤ 210 μmol/L \[≤ 2.38 mg/dL\]; albumin ≥ 28 g/L. 3. Renal function: Serum creatinine not exceeding 1.5 times the upper limit of normal. Exclusion Criteria: * Malignant tumors other than BTC; * Moderate to severe ascites (ascites reaching a Child-Pugh score of 3); * Any local treatment (including transcatheter interventional therapy, ablation therapy, internal/external radiotherapy, etc.) or surgical resection or traditional Chinese medicine within 4 weeks before the combination of systemic chemotherapy and immunotherapy; * Incomplete data, such as incomplete laboratory test data, missing or poor-quality imaging data, or lack of prognostic information; * Severe liver dysfunction, such as decompensated cirrhosis and other liver diseases that significantly affect bilirubin levels; * Severe comorbidities, such as refractory hypertension (blood pressure still higher than 150/100 mm Hg after optimal drug treatment), persistent arrhythmia (CTCAE grade 2 or above), any degree of atrial fibrillation, prolonged QTc interval (more than 450 milliseconds in men and more than 470 milliseconds in women), renal insufficiency, etc.; * Human immunodeficiency virus (HIV) infection or acquired immune deficiency syndrome; * Pregnant or lactating women; * Acute or chronic mental disorders (including mental disorders that affect the subject's enrollment, treatment intervention, and follow-up).