CNS metastasis

Cerebral Metastasis Breast Cancer

Diagram showing cancer cells spreading into the blood stream CRUK 448

Metastatic angiosarcoma in the brain

MRS 112040

Central Nervous System (CNS) Metastasis refers to the spread of cancer cells to the Central Nervous System, which includes the brain and spinal cord. It is a serious and unfortunately common complication of systemic cancer, significantly impacting patient prognosis and quality of life. CNS metastases can originate from various primary cancers, with lung cancer, breast cancer, melanoma, kidney cancer, and colorectal cancer being among the most frequent sources.

Etiology and Pathogenesis

The process of metastasis involves cancer cells breaking away from the original (primary) tumor, traveling through the body via the bloodstream or lymphatic system, and establishing new tumors (metastases) in the brain or spinal cord. The exact mechanism by which cancer cells breach the blood-brain barrier (BBB) is complex and involves multiple steps, including evasion of the immune system, adhesion to the endothelial cells of the BBB, and eventual invasion into the CNS tissue.

Clinical Presentation

Symptoms of CNS metastasis vary depending on the location and size of the metastases but may include headaches, seizures, neurological deficits (such as weakness or numbness in parts of the body), cognitive impairments, and changes in personality or behavior. The onset of symptoms can be gradual or sudden.

Diagnosis

Diagnosis of CNS metastasis typically involves a combination of patient history, physical examination, and imaging studies. Magnetic resonance imaging (MRI) is the gold standard for detecting brain metastases due to its high sensitivity and ability to provide detailed images of brain structures. In some cases, a biopsy may be necessary to confirm the diagnosis and determine the primary cancer source.

Treatment

Treatment options for CNS metastasis depend on several factors, including the number and size of metastases, the primary cancer type, the patient's overall health, and the presence of metastases in other parts of the body. Treatment modalities may include:

• Surgery: For accessible lesions and when there is a limited number of metastases.
• Radiation therapy: Including whole-brain radiation therapy (WBRT) for multiple metastases and stereotactic radiosurgery (SRS) for fewer, smaller lesions.
• Chemotherapy: Although the effectiveness of chemotherapy is often limited by the blood-brain barrier, certain drugs and novel delivery methods are being explored.
• Targeted therapy and immunotherapy: Especially for tumors with specific genetic mutations or characteristics.

Prognosis

The prognosis for patients with CNS metastasis is generally poor, with survival times often measured in months. However, outcomes can vary significantly based on factors such as the primary cancer type, the number and location of metastases, and the treatments applied. Advances in targeted therapies and immunotherapies are offering new hope for some patients.

Prevention and Screening

There are no specific measures to prevent CNS metastasis in cancer patients. However, early detection of primary cancer and aggressive management of known metastatic disease may reduce the risk of CNS involvement. For certain high-risk patients, regular screening with brain MRI may be recommended.