1. What is brain metastasis?
Brain metastasis, also known as secondary brain tumor, is the opposite of primary brain tumor and refers to the metastasis of malignant tumors from various parts of the body to the brain. Brain metastasis is the most serious complication of malignant tumor in all organs and systems of the body, and it is also the most common brain tumor in adults.
2. Are brain metastases common?
Brain metastases are the most common intracranial tumor in adults, and the incidence is about 10 times higher than that of primary intracranial tumors. Statistics show that about 8% to 10% of patients with malignant tumors will develop intracranial metastases, and the actual incidence may be higher. In other words, about 1/10 or more of malignant tumors in all parts of the body (such as lung cancer, thyroid cancer, breast cancer, esophageal cancer, melanoma, kidney cancer, stomach cancer, colon cancer, rectal cancer, pancreatic cancer, liver cancer, bone and soft tissue sarcoma, non-Hodgkin’s lymphoma and leukemia), regardless of their origin, will develop intracranial metastasis, and the most common cause of death for these patients is often intracranial metastasis as well.
3. Which tumors are most likely to have brain metastases?
Statistics show that the malignant tumor with the highest incidence of brain metastasis is malignant melanoma, but lung cancer is still the most common source of intracranial metastasis, accounting for about 50% of intracranial metastases. Next, such as breast cancer, melanoma, kidney cancer, rectal cancer, soft tissue sarcoma, breast cancer and non-Hodgkin’s lymphoma are also more common.
4. What parts of the skull can develop brain metastases?
Malignant tumors can metastasize to the skull, meninges and brain parenchyma, which can be divided into metastases in the skull, dura mater, soft meninges and brain parenchyma according to different sites, among which the latter two account for more than 80%.
Among brain metastases, about 80% of them occur in bilateral cerebral hemispheres (especially the corticomedullary junction in the blood supply area of middle cerebral artery is the most common), 15% in cerebellum and 5% in brainstem, among which multiple cases account for more than 50%.
5. What are the manifestations of brain metastases?
Based on the history of the primary tumor, patients with progressively worsening headache, accompanied by nausea, vomiting and other symptoms of increased intracranial pressure, or neurological localization signs such as epilepsy, limb weakness, limb sensory disorder, aphasia and unconsciousness should consider the possibility of brain metastases.
6. What tests can be done to know if it is a brain metastasis?
(1) CT scan shows hypodensity or isodensity (high density for metastatic lymphoma), and there may be cystic lesions surrounded by obvious finger-like distribution of hypodense edema bands; after enhancement, it shows irregular thick-walled, annular enhancement with nodules or regular, uniform thin-walled enhancement, with the most obvious enhancement of intracranial metastases of choriocapillaris, melanoma, thyroid cancer and adrenal cancer.
(2) MR scan flat scan is long T1 and long T2 signal, similar to gray matter; the T2 signal of edema is significantly higher than that of tumor; it can show intra-tumor hemorrhage not contemporaneously.
(3) PET-CT helps to distinguish the malignancy of tumors, identify recurrent tumors from necrosis after radiation or chemotherapy, and postoperative changes.
(4) Laboratory examination of cerebrospinal fluid exfoliation cytology helps to clarify whether there is soft meningeal involvement, and tumor marker examination helps to determine the source of metastasis.
7. How to treat brain metastases?
(1) Symptomatic treatment: antiepileptic drugs such as sodium valproate; steroid hormones can help reduce edema, improve the quality of survival and prolong survival; dehydrating agents such as mannitol can be used for those with obvious increase in intracranial pressure.
(2) Etiological treatment mostly uses local treatment (surgery or radiosurgery) combined with whole brain radiation (WBR). With the advancement of surgical techniques, surgical resection + whole brain radiation therapy is now the standard treatment for intracranial single brain metastases. In view of the possibility of combined metastases from other sites, it is recommended that patients be seen in a large general hospital with strong strength in all departments.
Surgical treatment is suitable for the following cases: the primary site is unclear; the primary site is clear but the nature of the intracranial lesion is unclear (e.g. breast cancer combined with meningioma); the primary tumor has been controlled but there is a single intracranial metastasis; the primary tumor is not controlled but the symptoms caused by the metastasis are obvious and can be easily removed by surgery. The role of surgery is not only to obtain pathology, but also to reduce the occupying effect and symptoms of cranial hypertension by removing the tumor, and to obtain opportunities for further radiotherapy, thus significantly prolonging the survival of patients.
②Radiation therapy is used for multiple metastases; those with poor general condition, rapid progression of primary disease and KPS <70 score are treated with whole brain radiotherapy alone; those with more stable disease and kps >70 score are considered for whole brain radiotherapy when recurrence or new lesions appear after postoperative or radiosurgery treatment. For certain smaller multiple deep lesions, solid metastases with insignificant occupancy effect and sensitive to radiotherapy, stereotactic radiosurgery can be considered, which has the advantage of being minimally invasive, but complications such as radiation edema and radiation necrosis may occur.
(iii) The role of systemic chemotherapy for brain metastases is unclear, but it is effective for some recurrent metastases such as small cell carcinoma, breast cancer, germ cell tumor and non-Hodgkin’s lymphoma.
8. What is the prognosis of brain metastases?
If brain metastases are not treated promptly, the average survival of patients is only about 3 months. If surgery-based comprehensive treatment is performed, patients’ survival can be significantly prolonged and their quality of life can be significantly improved. Therefore, brain metastases are often the most important factor in determining the survival of cancer patients. With effective control of brain metastases, the survival of patients can be effectively prolonged. The survival is mainly related to the degree of progression of the primary disease, the patient’s KPS score, the number and location of metastases and the patient’s age.