bubble_chart Overview

Intracranial metastatic tumors are malignant tumors from other parts of the body that spread to the intracranial region. Carcinomas, fleshy tumors, and melanomas can all metastasize to the brain. Clinically, most intracranial metastatic tumors are carcinomas, accounting for over 90% of cases. Malignant tumors spread to the brain through three main pathways: ① hematogenous spread, ② lymphatic spread, and ③ direct invasion, with hematogenous spread being the most common route. The pathway and site of metastasis are related to the location of the primary tumor. For example, lung cancer, breast cancer, and skin cancer primarily spread through the bloodstream, often forming multiple metastatic lesions in the brain. Gastrointestinal cancers are more likely to metastasize via the lymphatic system, spreading to the meninges.

bubble_chart Epidemiology

There are more males than females, with a male-to-female ratio of approximately 1.5:1. It is most commonly seen between the ages of 40 and 50.

bubble_chart Clinical Manifestations

Due to the rapid growth of the tumor and the severe reaction of brain tissue, the course of the disease is generally quite short. If the tumor bleeds, symptoms progress rapidly. If there is intratumoral necrosis forming a cyst, symptom progression is also relatively fast. Multiple tumors present with more severe symptoms and a shorter disease course. In 70–90% of cases, the disease course is within half a year, rarely exceeding 1 year, with individual cases lasting 2–3 years. The average duration is 3.5–4 months.

Symptoms primarily manifest in two aspects: increased intracranial pressure with general symptoms and localized symptoms.

1. Increased intracranial pressure and general symptoms: Due to the rapid tumor growth and severe surrounding brain edema, symptoms of increased intracranial pressure appear early and are pronounced. Approximately 90% of patients experience headaches, around 70% have nausea and vomiting, and over 70% exhibit papilledema. In 30–40% of cases, fundus hemorrhage occurs, leading to visual impairment in about 20%. Around 15% of patients have abducens nerve palsy. In advanced stages, about 15% of patients exhibit varying degrees of impaired consciousness and may show signs of brain herniation.

The general condition of patients is often poor, with some showing significant weight loss. About 20% of patients experience epileptic seizures, mostly focal seizures. Since tumors frequently involve the frontal and temporal lobes and brain edema is widespread, psychiatric symptoms are also common. Typical manifestations include slow response and apathy. Meningeal metastasis primarily presents as increased intracranial pressure and meningeal irritation signs, with localized signs being rare.

2. Localized symptoms: Due to the severe damage to the brain caused by the tumor and its often multifocal nature, localized symptoms are usually pronounced and involve a wide range. Corresponding signs arise depending on the tumor's location. Over 40% of patients experience hemiplegia, about 15% have hemisensory impairment, around 10% exhibit aphasia, and approximately 5% have hemianopia. Tumors located in the cerebellum may cause nystagmus, ataxia, and symptoms related to the lower cranial nerves.

bubble_chart Auxiliary Examination

1. Blood test: Half of the patients show accelerated erythrocyte sedimentation rate, often with increased white blood cell count in peripheral blood, and decreased red blood cells and hemoglobin.

2. Skull X-ray: Most cases exhibit signs of increased intracranial pressure, with occasional cases showing calcification and displacement of the pineal gland.

3. CT scan: Not only can it locate the tumor, but it can also display the size, shape of the tumor, and changes in brain tissue and ventricles. It is particularly effective in detecting multiple tumors. The tumors may appear roundish or irregular in shape, showing high density or mixed-density images. Mixed-density images often indicate necrotic or cystic changes within the tumor, presenting as low-density areas. After contrast enhancement, most tumors show significant block-like or ring-shaped enhancement, often surrounded by a low-density cerebral edema zone. Compression and deformation of the ventricles may be observed, while cerebellar tumors may show symmetrical enlargement of the ventricles above the third ventricle.

bubble_chart Diagnosis

Patients over 40 years old with rapid disease progression, shorter course, obvious symptoms of increased intracranial pressure, severe localized signs, and generally poor condition should first consider this disease. Since brain metastases often originate from the lungs, a chest X-ray should be taken. If a tumor is found on the chest X-ray or there is a history of malignant tumors in other areas, the diagnosis can generally be confirmed.

Further confirmation requires special examinations. CT scanning has the highest diagnostic value for localization, characterization, and detection of multiple tumors.

bubble_chart Treatment Measures

The treatment of intracranial metastatic tumors is challenging and difficult to cure. Comprehensive treatment is generally advocated as the primary approach, supplemented by radiotherapy, chemotherapy, etc., which can alleviate symptoms and prolong life.

Surgical treatment includes tumor resection and palliative or decompressive surgery. For solitary brain metastases, if the patient is in good general condition, the primary follicular tumor has been removed, and no metastases are found in other areas, tumor resection may be performed. If the primary tumor has not been removed but is resectable, and the brain symptoms—especially those of increased intracranial pressure—are significant, brain tumor resection may be performed first. After the intracranial pressure is relieved, the primary follicular tumor can then be resected. During tumor resection, the tumor is generally easy to separate from the brain tissue, and the resection should be as extensive as possible, aiming for complete removal. For deeply located or multiple tumors, as well as brain membrane metastases, decompressive surgery may be performed to alleviate symptoms.

For cases where the primary tumor cannot be removed, there are multiple metastases elsewhere in the body, or the patient is in poor general condition, surgery is not advisable. Hormones, dehydrating agents, and symptomatic treatment may be administered to provide short-term relief of symptoms.

For patients in good general condition post-surgery with normal blood counts, radiotherapy may be administered. Radiotherapy may also be considered for unresectable tumors without widespread metastases. Invasive tumors such as nasopharyngeal carcinoma, which are unsuitable for surgery, should be treated with radiotherapy. For patients in stable condition with normal blood counts and liver/kidney function, chemotherapy may also be considered. Drugs such as carmustine (BCNU), lomustine (CCNU), or other anticancer agents selected based on the type of primary tumor may be used.

bubble_chart Prognosis

The prognosis for brain metastases is poor. 50-70% of patients die within six months after surgery. Fewer than 15% survive for more than one year, with rare cases surviving over ten years. However, those who undergo surgery tend to have longer survival periods compared to those who do not. Therefore, surgical treatment still holds certain value for most suitable candidates, and an aggressive approach is advisable.