When Melanoma Spreads to the Brain

Introduction

Melanoma is one of the cancers most likely to spread to the brain. A large share of people with stage IV melanoma develop one or more brain metastases at some point during their illness, and many are found before they cause any symptoms. That is why a brain MRI is part of the standard staging workup and imaging for advanced melanoma, and part of follow-up afterward, even when a person feels completely well.

Hearing that melanoma has reached the brain is frightening, and for many years it carried a grim outlook. That has changed substantially. Modern immunotherapy and targeted therapy can work inside the brain, focused radiation can treat individual spots precisely, and surgery still has a role for certain lesions. Used together by an experienced team, these tools have turned brain metastases from a near-term crisis into something many people live with, and past, for years.

This page explains how brain metastases are found and followed, the local treatments (radiosurgery and surgery), and the systemic drugs that reach the brain. For the bigger picture of how advanced melanoma is treated, see the Advanced Melanoma hub and our overview of melanoma treatment options.

Why Melanoma Reaches the Brain So Often

Every cancer that spreads through the bloodstream can potentially reach the brain, but melanoma does so more readily than most. Among people whose melanoma has spread to distant sites, a large proportion — by many estimates roughly a third to a half, and more in autopsy studies — are found to have brain involvement at some point. The brain and its lining are simply a common destination for melanoma cells.

• •Brain metastases are more likely when the primary melanoma was thick or ulcerated, when disease has already spread to the lungs or liver, when the blood LDH level is elevated, and in melanomas carrying a BRAF or NRAS mutation.
• •Small brain metastases frequently cause no symptoms. Left undetected, they can grow to a point where they are harder to treat, so guidelines recommend looking for them proactively rather than waiting for a problem.
• •Finding them early genuinely changes the options: focused radiation and immunotherapy both work best on small, asymptomatic lesions in someone who is not on steroids.

This is the reasoning behind adding a contrast-enhanced brain MRI to staging for stage IV melanoma, and often for higher-risk stage III disease, even in the absence of any neurological complaint.

How Brain Metastases Are Found and Followed

The key test is a contrast-enhanced MRI of the brain. MRI is far more sensitive than CT for small lesions and for disease along the brain's lining, and the intravenous contrast (gadolinium) makes metastases stand out. A CT scan is used mainly when MRI cannot be done — for example, with certain implanted devices.

• •At staging: a baseline brain MRI is obtained when stage IV disease is diagnosed, and often when stage III disease is high risk, regardless of symptoms.
• •During treatment and follow-up: the brain is re-imaged on a schedule — commonly every 2 to 4 months at first — because the brain can be a site of progression even when disease elsewhere is controlled.
• •After radiosurgery: close MRI follow-up helps distinguish a lesion that is regrowing from radiation change (treatment-related inflammation), which can look similar and sometimes needs specialized imaging to sort out.

PET/CT scans, which are used to survey the rest of the body, do not reliably show brain metastases because normal brain tissue takes up the tracer — another reason a dedicated brain MRI is needed.

Systemic Treatment That Reaches the Brain

A major shift over the past decade is that melanoma drugs given by infusion or by mouth can shrink metastases inside the brain, not just elsewhere in the body.

• •Combination immunotherapy (ipilimumab plus nivolumab) has meaningful activity inside the brain. In the CheckMate 204 trial, roughly half of people with small, asymptomatic brain metastases who were not taking corticosteroids had an intracranial response, and many of those responses were durable. People with symptoms or on steroids did less well. See immunotherapy for advanced melanoma for how these drugs work and their side effects.
• •BRAF/MEK inhibitors (for melanomas with a BRAF V600 mutation) also reach the brain. In the COMBI-MB study, dabrafenib plus trametinib shrank brain metastases in a majority of patients and tended to work quickly, but the responses were generally less durable than outside the brain — often lasting a matter of months. This makes targeted therapy useful for rapid control or as a bridge. See targeted therapy with BRAF/MEK inhibitors.
• •Corticosteroids (such as dexamethasone) reduce brain swelling and can quickly ease symptoms, but they also dampen the immune system and appear to blunt the benefit of immunotherapy. Teams therefore use the lowest dose for the shortest time that controls symptoms, and lean on radiosurgery or surgery to reduce the need for them.

For many people the plan combines approaches — for example, radiosurgery to the lesions causing concern plus combination immunotherapy for long-term control — decided case by case.

Conclusion

Melanoma spreads to the brain more often than most cancers, which is why a brain MRI is part of staging even when there are no symptoms. When metastases are found, treatment usually combines a local approach — stereotactic radiosurgery for a limited number of lesions, or surgery for a large, symptomatic, or solitary one — with systemic therapy that can act inside the brain.

Combination immunotherapy produces durable responses in a substantial share of people with small, steroid-free brain metastases, and BRAF/MEK inhibitors add a fast option for BRAF-mutant disease. Leptomeningeal disease remains harder to treat. Managed by a combined neurosurgery, radiation oncology, and medical oncology team, brain metastases from melanoma carry a far better outlook than they did a decade ago.