1. Is kidney cancer prone to metastasis? To which parts of the body does it often metastasize? Renal cell carcinoma accounts for about 2% of all tumors in the body, and about 1/3 of patients have metastasis at the time of consultation. 40% of the remaining 2/3 of patients whose tumors are confined to the kidney will still have metastasis after nephrectomy. Statistics show that about 30% to 40% of patients with renal cell carcinoma will eventually metastasize. The most common sites of metastasis are lung (65%), bone (40%), liver (40%), adrenal gland (8%) and brain (5%). 2. Is brain metastasis of kidney cancer common? About 30% to 40% of patients with renal cell carcinoma will eventually develop metastases, of which 5% are brain metastases. Among the patients with metastasis, about 12% of brain metastasis is the earliest metastatic site. 3. What are the characteristics of kidney cancer brain metastasis? What is the impact on the choice of treatment method? About half of the brain metastases from renal cell carcinoma are single metastases, and they are often combined with severe edema around the metastases, so surgical resection should be given priority. Stereotactic radiosurgery can be considered for certain tumors located deep in the brainstem, thalamus, basal ganglia and other sites with small lesions. 4. What are the manifestations of brain metastasis of kidney cancer? What symptoms should be alerted? The most common symptoms of renal cell carcinoma brain metastasis are headache (24%), fatigue (20%), cognitive impairment (14%), seizure (12%) and ataxia; 7% have no clinical symptoms; those with multiple metastases may show cognitive impairment, emotional instability, blurred vision and optic papilledema. Therefore, patients with a history of renal cell carcinoma should promptly visit the neurosurgery department once the above manifestations appear. 5. What tests should be done to confirm the diagnosis when kidney cancer brain metastasis is suspected? CT examination may miss some smaller lesions, especially those in the brainstem and cerebellum located in the posterior cranial fossa. 6. What are the factors affecting the prognosis of renal cell carcinoma brain metastasis? The number of metastases, pre-treatment with or without chemotherapy, general condition, weight loss and time from diagnosis to treatment. 7. How should brain metastasis of renal cell carcinoma be treated? Surgery and radiotherapy are the main treatments for renal cell carcinoma brain metastasis, chemotherapy and immunotherapy are almost ineffective. (1) Surgery is the first choice for brain metastasis of renal cell carcinoma because half of the metastases are solitary metastases and the edema around the lesions is severe, so only by removing the lesions can the peritumor edema associated with the tumor subside. Surgery is especially suitable for the following cases: (1) single large metastases, especially those causing headache, dizziness and other symptoms of increased intracranial pressure; (2) metastases causing related symptoms, such as epilepsy, hemiplegia, aphasia and sensory disorders; (3) metastases located in the posterior cranial fossa; (4) patients in good physical condition who can tolerate surgery. (2) Whole-brain radiotherapy surgery combined with whole-brain radiotherapy can reduce the tumor recurrence rate at the resection site. Corticosteroids combined with whole-brain radiotherapy can also help relieve patients’ symptoms, but their symptom improvement does not correlate with imaging tumor shrinkage. (3) Stereotactic radiosurgery (such as gamma knife) can be used alone or in combination with whole brain radiotherapy, but tumor shrinkage can only occur 6 to 12 months after treatment, and it does not provide timely relief of signs and symptoms due to tumor compression.