This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Medicine
[{'content': 'Treatment of choice for hairy cell leukaemia is \nSelect and explain. \nA. Steroids, B. Cladribine, C. Splenectomy, D. Pentostatin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The first-line therapy for hairy cell leukemia is cladribine, 0.1 mg/kg/d by continuous intravenous infusion for 7 days. The drug can be administered on an outpatient basis with a pump, after placement of a percutaneous intravenous central catheter (PICC). Ref Harrison 20th edition pg 544', 'role': 'assistant'}]