This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Indications for instituting single-agent chemotherapy following evacuation of a hydatidiform mole usually include \nSelect and explain. \nA. A rise in hCG titers, B. A plateau of hCG titers for 1 week, C. Return of hCG titer to normal at 6 weeks after evacuation, D. Appearance of liver metastasis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Mishell, 3/e, pp 455-456.) Single-agent chemotherapy is usually instituted if levels of hCG remain elevated 8 weeks after evacuation of a hydatidiform mole. Approximately 50% of the patients who have persistently high hCG titers will develop malignant sequelae. If hCG titers rise or reach a plateau for 2 to 3 successive weeks following molar evacuation, a single-agent chemotherapy should be instituted, provided that the trophoblastic disease has not metastasized to the liver or brain. The presence of such metastases usually requires initiation of combination chemotherapy.', 'role': 'assistant'}]