Metastases to central nervous system Treatment

Managing Symptoms with Medications

Before or alongside definitive treatment, managing symptoms is crucial for patient comfort and function. Corticosteroids, particularly dexamethasone, are commonly prescribed to reduce brain swelling (called edema) that often surrounds metastases. A typical starting dose is 4 to 6 milligrams every six hours. These medications work remarkably well at reducing symptoms such as headaches, nausea, vomiting, and neurological deficits caused by swelling. The improvement is often noticeable clinically even before imaging shows significant changes.34

However, corticosteroids must be used carefully because they can cause side effects. They can disrupt blood sugar control, making diabetes worse or triggering new cases. They increase the risk of stomach ulcers and bleeding, make infections more likely, and can suppress the adrenal glands if used for extended periods. After definitive treatment, doctors usually taper the dose gradually to avoid withdrawal symptoms.4

Seizures are another common complication when cancer spreads to the brain. They can significantly complicate patient care and affect quality of life. Because of this risk, many doctors start anticonvulsant therapy even if the patient has never had a seizure. Levetiracetam at doses of 500 to 1,000 milligrams twice daily is a popular choice today. Another option is phenytoin at 100 milligrams three times daily, which has been used for decades.43

Surgical Treatment

Surgery plays an important role for carefully selected patients with brain metastases. Surgical removal can provide several benefits: it confirms the diagnosis through tissue examination, reduces pressure inside the skull by removing tumor mass, improves neurological symptoms, and may extend overall survival. Studies show that surgery can achieve these goals with relatively low rates of complications.2

To benefit from surgery, patients generally need to be in reasonably good medical condition, with their systemic cancer under control or controllable. Surgery is most often recommended when there is a single metastasis or a small number of accessible tumors, when the tumor is causing significant symptoms due to its size or location, or when the diagnosis is uncertain and tissue is needed for analysis.2

The surgical approach and extent of removal depend on the tumor's location in the brain or spinal cord. Recovery time varies, but many patients experience relief from symptoms caused by tumor pressure relatively quickly after surgery.

Radiation Therapy

Radiation therapy is a cornerstone of treatment for metastases to the central nervous system. The approach to radiation has evolved significantly in recent years, with important implications for patient outcomes and quality of life.1

Stereotactic radiosurgery (SRS) has become increasingly important in modern treatment. Despite its name, it is not actually surgery—it's a highly focused radiation treatment that delivers a high dose of radiation precisely to the tumor while minimizing exposure to surrounding healthy brain tissue. This approach is now often preferred over whole-brain radiation for treating a limited number of metastases. SRS can be performed in one or a few sessions and causes less cognitive side effects than whole-brain radiation.12

Whole brain radiotherapy (WBRT) involves treating the entire brain with radiation. Traditionally, this was the standard approach even after surgical removal of metastases, with the goal of catching tiny, invisible tumor deposits before they grew large enough to cause problems. However, this approach is not without risks. Whole-brain radiation can contribute to cognitive decline over time, particularly in patients who survive more than a year. Because of these concerns, many doctors now try to limit or defer whole-brain radiation, focusing instead on treating only visible tumors with surgery or stereotactic radiosurgery, then monitoring closely for new metastases.4

For spinal cord metastases, radiation therapy is generally considered a palliative treatment. In some cases, specialized techniques like Cyberknife stereotactic radiosurgery can be used for spinal metastases as well.2

Systemic Therapies

Chemotherapy and other systemic treatments depend heavily on the type of primary cancer. Different cancer types respond to different drugs. Traditionally, many chemotherapy drugs had limited ability to reach the brain because of the blood-brain barrier—a protective system that normally prevents many substances from entering brain tissue. However, when metastases form, they often disrupt this barrier, and modern targeted therapies have been designed to penetrate into the central nervous system more effectively.1

The role of chemotherapy in treating spinal cord metastases is less clear, though it may help control systemic disease. The choice of chemotherapy and its effectiveness depend on the characteristics of the original cancer.2

Targeted Therapies

One of the most exciting developments in recent years has been the multiplication of targeted therapies—drugs designed to attack cancer cells based on specific molecular characteristics. These therapies work by interfering with particular molecules or pathways that cancer cells need to grow and survive. Unlike traditional chemotherapy, which affects all rapidly dividing cells, targeted therapies aim to be more selective.1

For patients whose tumors harbor targetable mutations—specific genetic changes that can be addressed with available drugs—there may be the opportunity to try an orally bioavailable targeted therapy instead of or before radiation. This represents a significant shift in thinking. These targeted drugs are increasingly designed to penetrate the central nervous system effectively, addressing a major historical limitation.1

To identify whether a patient's tumor has targetable mutations, doctors now routinely perform genomic sequencing on resected metastases. Additionally, molecular analyses of spinal fluid—sometimes called liquid biopsies—can help characterize the disease without invasive procedures. These techniques allow doctors to match patients with the most appropriate targeted therapies.1

Clinical trials testing targeted therapies typically proceed through three phases. Phase I trials focus on safety, determining what dose can be given safely and what side effects might occur. Phase II trials assess whether the treatment works—does it shrink tumors or slow their growth? Phase III trials compare the new treatment with current standard options to determine if it's better, equivalent, or inferior.1

Immunotherapy

Immunotherapy represents another major frontier in cancer treatment. These approaches harness the patient's own immune system to recognize and attack cancer cells. Various immunotherapy strategies are being tested for metastases to the central nervous system.1

Some immunotherapies work by blocking proteins that cancer cells use to hide from the immune system. Others stimulate immune cells to become more aggressive against cancer. The brain was once considered an "immunological sanctuary site"—a place protected from immune system activity. While this protection may have allowed metastases to establish themselves more easily, it also meant that unleashing immune responses there could potentially be very effective.5

Clinical trials are testing various immunotherapy approaches, sometimes in combination with other treatments. Preliminary results from some trials have shown encouraging signs, including tumor shrinkage, stabilization of disease, and acceptable safety profiles. However, immunotherapy can cause unique side effects related to immune system overactivation, which must be carefully managed.1

Understanding the Tumor Microenvironment

Researchers are increasingly focused on understanding how metastatic cancer cells interact with the brain's unique environment. The cells surrounding tumors—including microglia (the brain's resident immune cells), blood vessels, and other supporting cells—play complex roles in either supporting or fighting cancer growth.5

Microglia, which represent about 50 percent of the total metastatic tumor mass in the brain, can be turned into either tumor-supporting or tumor-fighting cells depending on the conditions. Clinical trials are exploring ways to manipulate these cells and the broader tumor microenvironment to make it less hospitable to cancer. This includes testing drugs that affect specific molecular pathways, receptors, or inflammatory processes that influence how cancer cells survive and grow in the brain.5

Participation and Access to Clinical Trials

Clinical trials are conducted at major cancer centers in many locations, including the United States, Europe, and other regions worldwide. Some trials are available in multiple countries, while others may be limited to specific locations. Eligibility for trials depends on many factors, including the type of primary cancer, the extent and location of metastases, previous treatments received, overall health status, and specific characteristics of the tumor identified through genomic testing.1

Patients interested in clinical trials should discuss this option with their oncology team. The process typically involves detailed screening to determine eligibility, informed consent explaining the trial's purpose and potential risks and benefits, and close monitoring throughout participation. While clinical trials offer access to cutting-edge treatments, it's important to understand that experimental therapies may not work better than standard treatments and may have unexpected side effects.