How melanoma can spread from your skin to your brain

When former U.S. President Jimmy Carter announced that not only did he have melanoma, but that it had spread to his liver and brain, many people probably had the same thoughts: Isn’t melanoma skin cancer? And how do you get it on your brain?

“People think, 'Oh, it's melanoma that's just skin cancer – you cut it out and you don't have to worry about it,'” says Dr. Tim Turnham, executive director of the Melanoma Research Foundation in Washington, D.C.

“That thought has two implications: it isolates patients – often people diagnosed with melanoma feel people don't understand that they’re dealing with a life threatening illness because they think it's 'Cancer Lite' – but more significantly, it means that people don't understand the risks and don't take appropriate steps to alleviate those risks.”

One of those risks is that melanoma can metastasize to other, more vulnerable, parts of the body.

How Melanoma Spreads

Melanoma is particularly nefarious form of skin cancer. According to The Skin Cancer Foundation, though it accounts for less than two per cent of all skin cancer diagnosis, melanoma is responsible for the vast majority of skin cancer deaths. This is because it is the skin cancer most likely to metastasize to other organs.

Melanoma forms when the melanocyte cells that produce the melanin responsible for the pigment of your skin become malignant and form a cancer. While melanoma is usually confined to the surface of the skin, in rare cases, it can also develop in the eye or mucosal membrane. In any case, as that spot grows, it has more of a chance to spread.

“What commonly happens is as those malignant cells grower deeper into the skin, they eventually hit the lymphatic system – a series of tubes throughout the body, just like the blood vessels – and once there, they can travel to a lot of different places throughout the body. Sometimes they get caught up in the lymph nodes, but sometimes they go further and can show up in the brain and liver as President Carter's did, or show up in the bones, spleen and pancreas or any other organ,” says Turnham.

Melanoma is also one of the cancers that tends to metastasize to the brain. While no one quite knows for sure why that is, Turnham believes it has to do with receptors in the cancer cells.

“There are certain receptors in the cells that can react in different types of cellular environments and it may be that cells are migrating through the body and when they get to the brain they stick,” he says.

For example, ocular melanoma is a very rare form of melanoma with only about 1,000 cases a year in the U.S., but half of those cases metastasize and 90 per cent of the metastasis will go to the liver.

“It's all because of the kinds of genetic mutations in those melanocytes that activate receptors that tend to bind to liver cells,” says Turnham.

How Do You Know You Have Melanoma?

The most dangerous thing about melanoma, and why it's so misunderstood, is what you don't see.

“You can have a spot on your skin that can be relatively small and relatively innocuous, but what you don't see are those cells getting deeper and getting into that highway known as the lymphatic system and spreading to other parts of your body,” says Turnham.

“For many people, the first time they know they have melanoma – and this is what happened to President Carter – is when they start having problems with those organs where those cells have stuck and started growing as metastasis.”

So how do you know you have melanoma before it's too late?

Turnham recommends looking for spots on your body that look different from other spots, as well as looking for spots that are changing. Melanomas also tend to be multi-coloured, dark and larger than a pencil eraser, but there are always exceptions to all of those tendencies.

“I've known people who've had melanoma that looked just like a bug bite – a perfectly round, pink spot,” he says.

Looking for things that look different and changing are the best ways to mitigate these exceptions along with staying vigilant about your body. Check everywhere at least once a month, especially if you have light skin, light eyes, red hair, a lot of moles or blistering sunburns as a child. People with those characteristics are at higher risk.

“We do recommend people do a good solid skin check once a month, which means looking at your back, your scalp and behind your ears. If you have a husband or wife that can help you look at your skin that's great and if not, you should get in front of a good mirror, while using a handheld mirror to look at the base of your spine, your shoulder blades and your scalp,” says Turnham.

If you see something that looks unusual, take a picture of it and then take another one the next month to see if it has changed. Annual skin checks under the supervision of a doctor are recommended for those who have higher risk.

How to Prevent Melanoma

In addition to regular skin checks, you can prevent melanoma before it even shows up on your body and it's with that classic tool you've already heard about – sunscreen.

“Between 80 to 90 per cent of all melanomas are caused by UV exposure,” says Turnham. “When the UV hits your skin, it damages the DNA inside those skin cells and they send an emergency signal to the melanocytes, which cause them to release pigment.”

This means that every time you have a tan it's a sign that you have damaged DNA in your skin cells, so sunscreen is imperative, particularly those that are broad spectrum – covering UV A and UV B rays – with an SPF of at least 30.

“Most people don't use enough sunscreen,” says Turnham. “If you're out in your bathing suit, you need at least a shot glass full of sunscreen to put over your entire body and you should reapply it every two hours.”

You should also avoid the noon day sun and never go into a tanning bed.

The Carter Legacy

Jimmy Carter has one of the greatest post-presidential legacies in American history and the publicizing of his battle with skin cancer may add melanoma awareness to that list. But though Carter has certainly added to the conversation, Turnham has another concern.

“In the past, when a celebrity makes a statement about a cancer, you see a big bump in public compliance towards screening, prevention and things like that, only to see it fade away a little bit,” he says.

“What we hope to do is build on this message and say this is not just about being aware, but about changing your lifestyle and making some very simple, straightforward decisions that will lower your risk of getting this cancer. Melanoma is number one cancer diagnosis for women in their twenties and yet, it's one of the most preventable cancers if people pay attention.”