Metastatic (Secondary) Brain Tumors

What is metastasis?

Metastasis is a process where cancer cells break off the original (primary) tumor and spread via the lymphatic system or bloodstream to other parts of the body. The new tumors formed are called metastatic or secondary tumors and they can develop in various organs including the brain.

When does cancer metastasize?

Metastatic brain tumors are relatively common among cancer patients, especially those with advanced stages of the disease. In many cases, metastatic cancer to the brain is diagnosed at the same time as the primary tumor. The likelihood of cancer metastasizing to the brain depends on various factors, including the type of cancer, its stage at diagnosis, and individual patient characteristics.

The most common types of cancer that can spread to the brain include:

• Lung
• Breast
• Melanoma
• Colorectal
• Kidney
• Thyroid

What causes metastasis?

Metastatic brain tumors form when cells from an existing tumor detach and spread to the brain, typically traveling through the bloodstream. The reason why some primary cancers are more likely to metastasize remains unclear. The following steps are how metastatic tumors form:

1. Detachment: Cancer cells break away from the primary tumor.
2. Invasion: These cells invade surrounding tissues and penetrate blood vessels or lymphatic vessels.
3. Circulation: The cancer cells travel through the bloodstream or lymphatic system to other parts of the body.
4. Arrest and Extravasation: They lodge in small blood vessels at distant locations and move through the vessel wall into the surrounding tissue.
5. Proliferation: The cancer cells begin to multiply and form new tumors at these distant sites.

Metastatic tumors retain the characteristics of the original cancer cells, so if breast cancer cells spread to the brain, the secondary tumors in the brain are made up of breast cancer cells, not brain cancer cells.

What are the symptoms of metastasis?

Neurological symptoms of brain metastasis vary based on their size, location, and growth rate. Common symptoms include:

• Headache
• Nausea and vomiting
• Vision problems
• Weakness or numbness in the face or limbs
• Dizziness or imbalance
• Seizures
• Memory loss
• Cognitive or personality changes
• Speech difficulties.

Other possible symptoms depend on the primary tumor and involvement of other parts of the body, and may include:

• Pain: Persistent or severe pain in bones or other affected areas.
• Fatigue: Unusual tiredness and lack of energy.
• Weight Loss: Unintentional and significant weight loss.
• Loss of Appetite: Decreased desire to eat.
• Swelling: Swelling in lymph nodes or other parts of the body.
• Jaundice: Yellowing of the skin and eyes if the liver is affected.
• Coughing or Coughing Up Blood: Shortness of breath or persistent cough if the lungs are affected.

How is metastatic cancer diagnosed?

Metastatic brain tumors are diagnosed through a combination of medical history, physical exams, and various diagnostic tests. Here are some of the main methods:

• Neurological exam: Initial assessment of symptoms and neurological function.
• Blood tests: Detection of tumor makers or abnormal levels of certain substances in the blood.
• Imaging tests: MRI, CT, PET scans are used to identify and locate the tumor.
• Biopsy: A sample of tumor tissue is obtained and examined under a microscope to determine the type of tumor.
• Molecular Testing: Analyzes the genetic makeup of the tumor to guide treatment decisions.

How is metastatic cancer treated?

Treatment of metastatic tumors typically involves a combination of therapies aimed at controlling the spread of cancer, alleviating symptoms, and improving quality of life.

Options include:

• Systemic Therapies:
• Local Therapies:
• Palliative Care: Focuses on relieving symptoms and improving quality of life.
• Clinical Trials: Participation in research studies testing new treatments.

Can metastasis be prevented?

If cancer is detected early, and surgery and adjuvant therapy (chemotherapy, radiation therapy, immunotherapy, targeted therapy) are given, it may lower the risk of metastasis.