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Moles, birthmarks, beauty marks.
痣，胎记，美人痣。
Most people have multiple moles, and they come in lots of different shapes and sizes.
大多数人都有不止一颗痣，痣的大小和形状也各不相同。
Usually they’re harmless, but occasionally they could be a sign of a very serious disease: melanoma.
痣通常是无害的，但有时也可能成为一种非常严重的疾病的征兆：黑色素瘤。
So, when is a mole just a mole, and how does it turn into a deadly form of cancer?
那么，什么样的痣就只是一颗痣呢？痣又是怎样变成一种致命的癌症的呢？
Now, not all melanomas start from a mole,
不是所有的黑色素瘤都是从痣演变过来的，
but all moles are made up of the type of cells that can become melanomas: melanocytes.
但是所有的痣都含有一种能够发展成黑色素瘤的细胞：黑色素细胞。
Hi, my name is Aaron Mangold. I'm an assistant professor of dermatology at the Mayo Clinic in Arizona.
大家好，我是亚伦· 曼戈尔德。我是亚利桑那州梅奥研究所的皮肤科助理教授。
I specialize in cancer genomics as well as utilizing advanced forms of genetics
我的研究方向是癌症基因组学以及利用先进的遗传学形式
to prognosticate cancers for spread to other areas of the body, as well as for therapeutic interventions.
预测癌症在身体其他部位扩散的可能性，以及进一步的治疗干预。
Melanocytes primarily protect skin cells from ultraviolet damage through the production of pigment called melanin.
黑色素细胞主要通过产生黑色素来保护皮肤细胞免受紫外线的伤害。
Melanocytes deliver melanin to the surrounding keratinocytes, or skin cells in the epidermis, giving our skin its color.
黑色素细胞会将黑色素输送给周围的角化细胞，或表皮的皮肤细胞，我们皮肤的颜色就是这么来的。
When we come in contact with ultraviolet light from the sun,
人体接触到来自太阳的紫外线时，
this melanin protects our skin from damage, while also signaling to the body to produce more melanin.
这种黑色素能够保护我们的皮肤免受伤害，同时向身体发出信号，促使其产生更多的黑色素。
This is why you might tan when you go out in the sun.
这就是为什么大家在阳光下会晒黑的原因。
And this system works pretty well, but it’s not perfect.
这一机能很管用，但并不完美。
So melanocytes really have evolved over time to be extremely resistant to ultraviolet light.
原来啊，随着时间的推移，黑色素细胞已经进化到对紫外线具有极强的抵抗力的水平了。
They've become extremely resistant to acquiring mutations that in normal cells might lead to apoptosis, or cell death.
对在正常细胞中可能导致细胞凋亡或死亡的突变也有了极强的抵抗力。
And they also are able to circulate innately throughout the body.
这些细胞还能在全身各处循环。
Since melanocytes aren’t as likely to die due to DNA damage from UV light,
由于紫外线造成的DNA损伤不太可能引起黑色素细胞的死亡，
they obtain mutations and can continue to grow and may cluster together,
它们可能因此发生突变，突变后还能继续生长，甚至聚集在一起，
forming non-cancerous growths called “nevi,” or moles.
形成一种叫做“色素痣”，也就是痣的良性肿瘤。
Those damaged melanocytes can then acquire additional mutations and continue to proliferate,
这些受损的黑色素细胞还能进一步突变，进一步增生，
forming a precancerous lesion or eventually a melanoma.
发展成癌前病变，最终形成黑色素瘤。
One mutation that almost all moles have is in the gene BRAF, a protein that is part of cell signaling involved in cell growth.
几乎所有色素痣都会发生的一种突变是基因BRAF——这是具有细胞信号传导功能，会影响细胞生长的一种蛋白质——的突变。
But, a single BRAF mutation is not enough to cause cancer.
不过，BRAF的单次突变并不足以引发癌症。
And not all melanomas even come from moles.
而且，并不是所有的黑色素瘤都是痣演变而成的。
So the way that melanoma, or the way that a melanocyte becomes a melanoma, occurs through a fairly long process.
黑色素瘤的形成，或者说黑色素细胞变成黑色素瘤是一个相当漫长的过程。
There's not one specific change that happens that leads to it.
这一结果并不是某一次特定的变化引起的。
It's a series of changes.
而是一系列的变化引起的。
Additional mutations in genes can be caused by things like further damage due to UV light.
基因的进一步突变可能是由紫外线造成的进一步损害等因素造成的。
These changes prevent natural cell death and lead to uncontrolled growth of the cancerous melanoma cells.
这些变化阻止了黑色素细胞的自然死亡，引起恶性黑色素瘤细胞不受控制的生长。
Fortunately, melanomas can be removed if discovered early enough.
幸运的是，发现及时的话，黑色素瘤还是可以祛除的。
And there are ways to check if a mole is irregular, which we’ll talk about a little later.
我们也有很多种办法来确认一颗痣究竟是不是有异常，这个我们等下再讲。
But, what happens if melanoma isn’t caught?
问题是，如果黑色素瘤没有被及时发现，结果会怎样呢？
The melanoma cells, they're able to acquire certain properties that make them not want to stay in the skin any more.
黑色素瘤细胞能够获得某些让它们不想继续留在皮肤层的属性。
And once they acquire those,
一旦他们获得了这些属性，
they can actually go into things called lymphatics in the bloodstream and then can spread.
它们就能进入血液中的淋巴系统并进一步扩散。
Once melanoma has reached this stage and has spread from the lymph nodes to other parts of the body, it’s very hard to cure.
一旦黑色素瘤发展到这个阶段，从淋巴结扩散到了身体的其他部位，就很难治愈了。
It also has a high mortality rate, only 23% of patients survive past five years.
黑色素瘤引发的死亡率也很高，只有23%的患者能够撑过5年。
So it’s important to identify an abnormal mole soon so that it can be removed.
所以，尽早发现异常痣是很重要的，这样才能及时将其切除。
Fortunately, there is an easy ABCDE rule to follow,
幸运的是，我们可以根据非常简单的ABCDE规则，
which checks for asymmetry, irregular borders, uneven color, increasing diameter and an evolution or change in the mole.
也即不对称、边缘不规则、颜色不均匀、直径增加以及痣在进化或变化这五点来判定一颗痣是否存在发展成黑色素瘤的可能性。
An individual might say that this lesion is just different.
有人可能会说，这种病变就是不一样。
This doesn't look like everything else on me.
因为它和我身上的其他任何部位都不一样。
That ugly duckling sign I think is also very useful in having some form of self body awareness and say, "I want this looked at."
在我看来，这个难看的标记也是很有用的，能够唤醒大家对自己的身体的一种自我意识，继而产生“我得找人帮我看看”这种念头。
Specialists like Dr. Mangold are also starting to use immunotherapy to combat later stage melanoma,
曼戈尔德博士等专家也已经开始使用免疫疗法，
using the body’s natural defenses to fight the disease.
也即利用身体的自然防御系统来对抗疾病的疗法，来治疗晚期黑色素瘤。
Normally our immune system will travel throughout the body, the immune cells will,
正常情况下，我们的免疫系统，具体来说就是我们的免疫细胞，会在我们的全身游走，
and those immune cells will look at individual normal cells and say, “How abnormal are you?”
这些免疫细胞会以“你有多不正常？”的姿态审视单个的正常细胞，
And when they have those signals telling them that they've acquired too much damage, the immune system then kills them….
当有信号告诉它们受审查的细胞已经受到了太多伤害时，免疫系统就会杀死这些细胞……
Well, cancer cells have figured out how to use certain proteins like that,
然而，癌症细胞已经知道如何利用这种蛋白质了，
they will say, Don't worry about it. Everything is okay. We're doing fine. Leave us alone.
他们会告诉免疫细胞，别担心，一切正常，我们都很好。您请回吧。
Recently, they figured out how to block those, how to block those signals that quiet the immune system.
最近，这些癌症细胞还想到了如何阻止，阻止那些信号并麻痹免疫系统的办法。
And it's really revolutionized, not just the care of cancer as it pertains to melanoma, but cancer in general.
这一疗法堪称颠覆了黑色素瘤的治疗方法，也颠覆了大部分癌症的治疗方法。
But immunotherapy is still an emerging science.
不过，免疫疗法仍然是一门新兴的科学。
Doctors have to avoid making the immune system too active.
医生必须避免让免疫系统变得过于活跃。
This would result in an autoimmune disease, or an immune system that attacks healthy cells.
因为免疫系统过于活跃就会引发自身免疫性疾病，也即免疫系统会攻击健康的细胞。
It's really analogous to playing a musical instrument or playing a piano.
这和演奏乐器或是弹钢琴是一个道理。
You have all the keys that are there.
所有的琴键都在那儿。
Yet, you can make good music, or you can make bad music.
用那些琴键，你既可以弹出好听的音乐，也能弹出难听的音乐。
And we're trying to figure out now, how do we make good music and how do we avoid that kind of bad music?
我们现在的课题就是怎样弹出好的音乐，以及怎样避免弹出糟糕的音乐？
While immunotherapy is still developing, there is one treatment that everyone can take part in.
虽然免疫疗法仍在摸索之中，但有一种治疗方法是大家都可以采用的。
You don't want people to lose sight of what's important,
你若不想大家忽略掉重要的问题，
and I think it was Bert Vogelstein who said this that
我记得没错的话，这句话应该是波特·福格斯坦说的，
if you could give someone a pill and tell them, “This pill that I give you is going to reduce your risk of cancer by 50%,”
如果你能给一个人一颗药丸，然后跟他们说，“我给你的这颗药丸能够将你患癌症 的风险降低50%，”
that it would be across every news organization, every magazine cover.
各大新闻机构，各大杂志封面都会竞相报道你的话。
Someone would get a Nobel Prize for it.
有人甚至会因此拿到诺奖。
And we do have that pill.
而且这个药我们已经有了。
That pill is primary prevention through healthy behaviors, healthy eating,
那就是早作预防，养成健康的生活习惯，健康的饮食习惯，
different things that we can do as individuals that will reduce those risks.
这些都是我们个人力所能及的降低这类风险的办法。
