This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Medicine
[{'content': 'Paraneoplastic erythrocytosis seen in which malignancy? \nSelect and explain. \nA. Renal Ca, B. Breast Ca, C. Thyroid Ca, D. Adrenal Ca', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) Renal Ca # ERYTHROCYTOSIS> Ectopic production of erythropoietin by cancer cells causes most paraneoplastic erythrocytosis.> The ectopically produced erythropoietin stimulates the production of red blood cells in the bone marrow and raises the hematocrit,> Approximately 3% of patients with renal cell cancer, 10% of patients with hepatoma, and 15% of patients with cerebellar hemangioblastomas have erythrocytosis. In most cases the erythrocytosis is asymptomatic.', 'role': 'assistant'}]