Skin cancer, like other forms of cancer, has the potential to spread from its original site to other parts of the body, including the brain. This process is known as metastasis. While it is possible for skin cancer to reach the brain, it is not an automatic or most common outcome for all types of skin cancer.
Understanding Metastasis
Metastasis is the process by which cancer cells detach from a primary tumor and travel to distant organs to form new tumors. These cells then move through the walls of nearby blood vessels or lymph nodes. Once in the bloodstream or lymphatic system, these cells can travel throughout the body. They may stop in a distant location, invade the vessel walls, and move into the surrounding tissue, beginning to grow and form a secondary tumor.
Skin Cancer Types Prone to Brain Spread
Melanoma is the most aggressive form of skin cancer and is the type most likely to metastasize to the brain. Approximately 40% to 60% of individuals with late-stage melanoma may develop brain metastases. This high rate of brain involvement makes melanoma the third most common cancer to colonize the brain, after lung and breast cancers. Other types of skin cancer, such as squamous cell carcinoma (SCC), can also spread to the brain, though this is less common than with melanoma. Brain metastases from SCC are a rare complication, occurring in less than 1% of all cases. Basal cell carcinoma (BCC), the most common type of skin cancer, rarely, if ever, spreads to distant sites like the brain. Factors increasing the risk of melanoma spreading to the brain include the primary tumor being on the head, neck, trunk, or abdomen, as well as being invasive or ulcerated.
Pathways of Spread to the Brain
Cancer cells from the skin primarily reach the brain through the bloodstream, a process known as hematogenous spread. The brain is protected by a specialized structure called the blood-brain barrier (BBB), which normally restricts the passage of many substances from the bloodstream into the brain. However, cancer cells can overcome this barrier through various mechanisms, making it more permeable and allowing them to infiltrate the brain tissue.
Signs of Brain Metastasis
When skin cancer spreads to the brain, it can lead to a variety of symptoms that depend on the size and location of the new tumor(s). Headaches are a common symptom, often described as persistent, worsening over time, and sometimes accompanied by nausea or vomiting. Other neurological symptoms can include seizures, which may manifest as episodes of numbness, tingling, or uncontrolled movements. Changes in mental function, such as memory problems, confusion, or personality shifts, can also occur. Individuals might experience weakness or numbness on one side of the body, balance issues, or difficulties with speech and vision. While these symptoms warrant medical evaluation, it is important to remember that many other conditions can cause similar signs.