Brain metastases

Definition

Metastatic brain tumors are secondary foci resulting from local aggressive growth, hematogenous and lymphogenousmetastasis of malignant neoplasms of other localizations. 30% of patients are asymptomatic. In other cases, brain tumors are manifested by headaches, dizziness, nausea, vomiting, focal symptoms, and mental and emotional disorders. When the spinal cord is affected, pain and sensory and motor disorders occur. Diagnosis is made by considering anamnesis, symptoms, CT, MRI, and other studies. Treatment is radiotherapy, less often surgical removal or chemotherapy.

General information

Metastatic brain tumors are a group of malignant neoplasms of various origins that have arisen in the spinal cord or brain as a result of the spread of cells from the primary tumor. Metastases in the brain are detected in every fifth cancer patient. According to various data, metastatic lesions of the spinal cord are observed in 30-70% of patients. Researchers say secondary CNS lesions are ten times more common than primary ones.

The peak incidence is between 50-70 years of age; men and women are affected equally often. Sometimes, the symptoms of a metastatic brain tumor are the first signal of another neoplasm. For example, 10% of patients with lung cancer first seek help due to the occurrence of neurological disorders. The prognosis is usually unfavorable; secondary brain damage is one of the leading causes of mortality in malignant tumors. Specialists in oncology and neurology provide treatment.

Reasons

Metastases to the CNS can occur in malignant neoplasms of any localization. From 30 to 60% of the total number of metastatic brain tumors appear in lung cancer, from 20 to 30% – in breast neoplasms. The third place in prevalence is occupied by metastases in melanomas (10%) and the fourth – in colorectal cancer (5%). Metastatic brain tumors are less common in lymphomas, sarcomas, and thyroid neoplasms.

Sometimes, the cause of secondary processes in the brain is infiltrative growth of nasopharyngeal neoplasms. Secondary spinal cord lesions resulting from aggressive growth of the primary focus can be detected in vertebral neoplasms, an abdominal form of Burkitt’s lymphoma, and other voluminous processes localized near the spinal canal. Among the rare cancers that are sometimes complicated by metastatic brain tumors are testicular teratoma and choriocarcinoma. Malignant tumors of the ovary, cervix, and bladder rarely metastasize to the brain for unknown reasons.

80% of metastatic brain tumors are located in the cerebral hemispheres, 15% in the cerebellum, and 5% in the brain stem. Most secondary foci in the spinal cord are localized at the lower thoracic or upper lumbar vertebrae level. Lesions of the dura mater account for about 10% of the total number of metastatic brain tumors. More than 70% of metastases are multiple, which worsens the prognosis. The histological structure of the secondary tumor is like that of the primary neoplasm. Symptoms are due to both direct pressure of the tumor on the nerve structures and perifocal edema of the surrounding tissues.

Symptoms of metastatic brain tumors

A metastatic brain tumor is manifested by headaches, dizziness, nausea, vomiting, seizures, impaired consciousness, sensory disorders, and focal neurological symptoms. Mental and emotional disorders are possible: emotional instability, drowsiness, lethargy, cognitive disorders, personality changes, etc. The severity of symptoms of metastatic brain tumor varies greatly – from minor memory or mood disturbances to severe epilepsies.

The dynamics of neurological disorders also vary. In some patients, the disorders gradually worsen, while in others, they develop suddenly, like a stroke. The sudden onset of symptoms may be caused by hemorrhage into a metastatic brain tumor or embolism of a vessel by a fragment of the neoplasm. Sometimes, there is a remitting course of the disease, in which focal and extracerebral disorders wax and wane.

Symptoms of metastatic spinal cord tumors

The first manifestation of a metastatic brain tumor is usually pain. At first, the pain syndrome is non-intensive and inconstant and occurs only when coughing and sudden movements. Subsequently, the pain intensifies, appears spontaneously, bothers constantly, and does not disappear even after sleep or prolonged rest. Progressive sensory and motor disorders are revealed. Hyperesthesia develops, followed by hypoesthesia and then anesthesia.

Patients with metastatic brain tumors report muscle weakness and rapid fatigue with physical activity. Over time, muscle weakness develops into paresis and paresis into paralysis. The level and localization of the metastatic brain tumor determine the area of sensory and motor disorders. In the case of lesions in the lateral sections, Broun-Sekar syndrome may be detected. Symmetrical disorders are usually observed in posterior or anterior tumors.

Diagnosis of metastatic brain tumors

An oncologist and neurosurgeon establish the diagnosis, taking into account clinical manifestations and data from additional studies. Anamnestic data play an important role: suspicion of a malignant tumor or the presence of an already diagnosed neoplasm of extracerebral localization, as well as the state after surgical or conservative treatment for this pathology. It should be taken into account that sometimes symptoms of metastatic brain tumor become the first manifestation of a pathological process in another organ.

Headaches, nausea, epileptiform seizures (found in 35% of patients), and progressive focal symptoms are warning signs for brain neoplasms. Suspicion of a secondary process in the spinal cord arises with prolonged increasing pain, motor and sensory disturbances, and pelvic organ disorders. The main instrumental methods of diagnosing metastatic brain tumors are CT and MRI. Usually, studies are started with more accessible CT of the brain and CT of the spine, and contrast-enhanced MRI obtains complete information about the number, size, and location of foci. In spinal cord lesions, lumbar puncture with liquor-dynamic tests is also informative. 

Treatment of metastatic tumors

Patients are prescribed anticonvulsants, steroids, painkillers, and psychotropic drugs. Radiotherapy is usually the primary method of treatment of metastatic brain tumors, and it is used separately or in combination with chemotherapy or surgery. The indication for surgical treatment is the presence of operable solitary metastasis (secondary focus in an undetected primary process) or solitary metastasis in a controlled primary neoplasm.

Surgery is usually performed for metastatic brain tumors located in the cerebellum, temporal lobes, and frontal lobes, i.e., in areas with relatively low surgical risk. After surgery, radiotherapy or chemotherapy is administered. Sometimes, the goal of surgical treatment is not to remove a metastatic brain tumor but to urgently reduce life-threatening intracranial pressure. If necessary, such interventions can be performed repeatedly.

Chemotherapy is usually ineffective. The exception is when the primary tumor responds well to cytostatics, such as in breast cancer, small-cell lung cancer, or lymphoma. Patients with a metastatic brain tumor that is sensitive to chemotherapy are prescribed drugs that can penetrate the blood-brain barrier. Chemotherapy is necessarily supplemented with other treatment options (usually radiotherapy).

A promising modern method of treatment of metastatic brain tumors is 3D conformal radiation therapy – irradiation with thin beams of radiation directed at the tumor. This technique allows maximum impact on the tumor with minimal radiation load on healthy tissues. The procedure is performed under the control of MRI or CT. The method has several advantages over traditional surgeries (painlessness, non-invasiveness, absence of anesthesia, and postoperative period). It is indicated for multiple metastatic brain tumors and at high surgical risk due to the specific location of the metastasis.

The same methods are used in secondary foci in the spinal cord as in brain lesions. Administration of corticosteroid drugs reduces pain in 85% of patients and radiotherapy – in 70% of patients. Improvement of motor functions is noted in half of patients on the background of radiotherapy. Surgical interventions are performed when metastatic brain tumors are insensitive to radiotherapy, when neurological disorders progress, or when a bone fragment compresses nerve tissue. Anterior decompression or laminectomy is performed. After surgery, local radiotherapy is administered (except for neoplasms insensitive to radiation therapy).

All these treatment options are available in more than 800 hospitals worldwide (https://doctor.global/results/diseases/brain-metastases). For example, Brain tumors surgery can be done in 30 clinics across Turkey for an approximate price of $11.4 K (https://doctor.global/results/asia/turkey/all-cities/all-specializations/procedures/brain-tumors-surgery). 

Prognosis

The prognosis for metastatic brain tumors is usually unfavorable. The average life expectancy from the moment of detection of the secondary focus is 6-8 weeks. In the case of solitary metastases and solitary metastases in combination with primary neoplasms that respond well to therapy, timely treatment can extend the average life expectancy of patients with metastatic brain tumors up to 10 months from the moment of diagnosis.