Brain metastases from lung cancer About 40% of lung cancer patients have brain metastases, and more than 70% of patients with brain metastases have neurological symptoms. brain metastases can be found at the same time as the primary lung lesion, or brain metastases can be the first symptom and then the primary lung lesion is found. Multiple brain metastases often occur in lung cancer, and isolated brain metastases only account for 1/3. Etiology and pathogenesis The etiology of brain metastases from lung cancer is not clear. Tumor cells may reach brain tissue through the anastomosing branches between cerebral blood vessels and vertebral arterial plexus, or tumor cells may metastasize to brain tissue via carotid artery, and the easy brain arteries are mainly the terminal branches of middle, posterior and anterior cerebral arteries. Clinical manifestations The symptoms of brain metastasis patients can be broadly divided into two categories One is the symptoms of intracranial hypertension caused by brain metastases and the other is the symptoms of brain nerve damage. The most common symptom is headache, vomiting mostly occurs when the headache is intense and is characterized by jet vomiting, followed by poor localization function and mental abnormalities. In addition, diplopia, paroxysmal blackness, sudden collapse, impaired consciousness, increased blood pressure, slowed pulse, and even respiratory arrest due to brain herniation caused by tumor compression are all possible symptoms in patients with brain metastasis. Intra-tumor hemorrhage can lead to dramatic worsening of symptoms. The most common sign is hemiplegia or abnormal movement, followed by sensory abnormalities and optic papilledema. Diagnosis The current diagnosis of brain metastasis is mainly based on imaging examinations, such as cranial CT and cranial MRI. cranial MRI is more likely to detect multiple brain metastases and brain metastases smaller than 1 cm than cranial CT. Treatment Surgical resection + postoperative whole brain radiotherapy has become the standard treatment mode, and its recurrence rate is much lower than that of whole brain radiotherapy alone. Therefore, for patients in good general condition who can tolerate craniotomy and have a single resectable lesion in both the brain and lung, the NCCN guidelines for the diagnosis and treatment of non-small cell lung cancer recommend active surgical resection treatment and whole brain radiotherapy after brain metastasectomy, respectively. In addition, stereotactic radiosurgery plus whole brain irradiation is also an option. Prognosis Median survival is only 4 weeks without treatment for brain metastases, 3-6 months with whole brain radiotherapy, and 2.5 months with a 1-year survival rate of 10.4% for patients with brain metastases. Patients with isolated brain metastases may benefit from surgical resection, with a 5-year survival rate of approximately 13% after surgical resection. Therefore, the prognosis of patients with isolated brain metastases is significantly better than that of patients with multiple brain metastases, and patients with isolated brain metastases should be actively treated with standardized therapy.