Brain metastases, a specific form of Stage IV melanoma, are one of the most common and difficult-to-treat complications of melanoma. They differ from all other metastases in terms of risk factors, diagnosis, and treatment.
Who Is At Risk?
More than 60% of all Stage IV melanoma patients will develop brain metastases at some point but certain factors can increase that risk: (1-2)
The primary tumor was on the head, neck, trunk or abdomen
The primary tumor was ulcerated or deep or invasive.
The melanoma was unresectable Stage III or Stage IV when diagnosed
The melanoma has spread to the internal organs
The LDH (serum lactate dehydrogenase) is elevated.
Why Are Brain Metastases So Difficult To Treat?
Brain metastases are difficult to treat. There are several potential reasons.
- There is growing evidence that brain tumors are very different from tumors in other parts of the body and need to be treated differently.
- The brain looks familiar. Melanocytes arise from the same part of the early embryo as the brain, so the brain might be a very natural environment for melanoma tumors to grow in.
- The brain has many defenses to reduce the penetration of harmful substances. This is called the blood-brain-barrier and it prevents many medications from entering the brain.
- Brain metastases tend to be very aggressive.
- Treatment options may damage surrounding normal tissue and have significant impact on the quality of life.
What Determines the Treatment Options and Prognosis For Patients With Brain Metastases?
Certain characteristics of both the patient and the cancer will affect the patients' prognosis as well as their eligibility for treatment. The following factors are associated with better outcomes: (3-5)
- Younger age: <60
- Fewer vs. more brain metastases: <3 lesions
- No extracranial disease: extracranial is the presence of disease outside the cranium
- Normal serum LDH
- High Karnofsky Performance Status (KPS) score (>70)
Unfortunately, melanoma brain metastases carry a poor prognosis, with a median overall survival of about 4-5 months. Often a patient first exhibits multiple, symptomatic lesions, making the condition difficult to treat surgically. However, improvements in radiation and systemic therapies are offering promise for this challenging complication, and some patients are curable.