Elizabeth Murchison: Fighting a contagious cancer

譯者: Yingzhi Vera Gu 審譯者: Josie Chen

Everyone's familiar with cancer,

每個人都熟悉癌症，

but we don't normally think of cancer

但是一般我們並不認為癌症

as being a contagious disease.

是一種傳染性疾病。

The Tasmanian devil has shown us

然而塔司馬尼亞惡魔告訴我們

that, not only can cancer be a contagious disease,

癌症不僅是一種傳染性疾病

but it can also threaten

而且它會威脅到

an entire species with extinction.

整個物種的存亡。

So first of all, what is a Tasmanian devil?

所以，首先，什麼是塔司馬尼亞惡魔呢？

Many of you might be familiar with Taz, the cartoon character,

許多人或許很熟悉塔司，

the one that spins around and around and around.

那個總是不斷旋轉的卡通動物。

But not many people know

但是，並不是很多人知道

that there actually is a real animal called the Tasmanian devil,

實際上真的有一種動物叫做塔司馬尼亞惡魔，

and it's the world's largest carnivorous marsupial.

而且牠是世界上最大的肉食性有袋類動物。

A marsupial is a mammal with a pouch

有袋類動物是一種有一個口袋的哺乳類動物

like a kangaroo.

比如袋鼠。

The Tasmanian devil got its name

塔司馬尼亞惡魔得名于

from the terrifying nocturnal scream that it makes.

牠在夜間發出的可怕尖叫聲。

(Screaming)

（尖叫）

(Laughter)

（笑）

The Tasmanian devil is predominantly a scavenger,

塔司馬尼亞惡魔主要以食腐為生。

and it uses its powerful jaws

牠用有力的下顎

and its sharp teeth

和尖銳的牙齒

to chomp on the bones of rotting dead animals.

啃食腐爛的動物屍體。

[The] Tasmanian devil is found only on the island of Tasmania,

唯有塔司馬尼亞島上才有這種動物。

which is that small island

這個小島

just to the south of the mainland of Australia.

就在澳洲大陸南方

And despite their ferocious appearance,

盡管長相兇惡，

Tasmanian devils are actually

塔司馬尼亞惡魔實際上

quite adorable little animals.

是一種很可愛的動物。

In fact, growing up in Tasmania,

實際上，牠在塔司馬尼亞成長，

it always was incredibly exciting

當我們有機會

when we got a chance to see

在野外親眼看見塔司馬尼亞惡魔時

a Tasmanian devil in the wild.

總是會感到非常興奮。

But the Tasmanian devil population

但是塔司馬尼亞惡魔的數量

has been undergoing a really extremely fast decline.

卻在急速減少中。

And in fact, there's concern

實際上，有人擔心

that the species could go extinct in the wild

這種動物可能會在20至30年間

within 20 to 30 years.

滅絕

And the reason for that

原因是

is the emergence of a new disease,

一種新疾病的出現，

a contagious cancer.

一種具傳染性的癌症。

The story begins in 1996

事情起自於1996年

when a wildlife photographer took this photograph here

一個野生攝影師拍下這張

of a Tasmanian devil

塔司馬尼亞惡魔的照片。

with a large tumor on its face.

牠的臉上有一個巨大的腫瘤。

At the time, this was thought to be a one-off.

當時，人們認為這是偶發狀況。

Animals, just like humans,

因為動物，就像人一樣，

sometimes get strange tumors.

有時也會長奇怪的腫瘤。

However, we now believe

然而，我們現在相信，

that this is the first sighting of a new disease,

這是某種目前正在塔司馬尼亞蔓延

which is now an epidemic spreading through Tasmania.

的傳染性疾病，最早被目擊的案例。

The disease was first sighted

這種疾病最早

in the northeast of Tasmania in 1996

是在1996年塔司馬尼亞州的東北部被發現的，

and has spread across Tasmania like a huge wave.

其後就如大浪般席捲了整個塔司馬尼亞。

Now there's only a small part of the population,

現在僅有一小部分

which remains unaffected.

未受傳染。

This disease appears first as tumors,

通常，在臉上或嘴裡

usually on the face or inside the mouth

長出腫瘤

of affected Tasmanian devils.

是塔司馬尼亞惡魔被感染後的第一病徴。

These tumors inevitably grow into larger tumors,

之後腫瘤就越長越大，勢不可擋，

such as these ones here.

就像這些一樣。

And the next image I'm going to show

我要讓各位看的下一張圖片

is quite gruesome.

十分可怕。

But inevitably, these tumors progress

但是，無可奈何是，這些腫瘤會

towards being enormous, ulcerating tumors like this one here.

越長越大，就像這個巨大的潰瘍性腫瘤。

This one in particular sticks in my mind,

這一個我特別難忘，

because this is the first case of this disease

因為這是在此種疾病中

that I saw myself.

我所見到的第一個案例。

And I remember the horror of seeing this little female devil

我還記得我見到這隻母塔司時的恐懼感覺。

with this huge ulcerating, foul-smelling tumor

她的嘴裏長着一個非常大的潰瘍性腫瘤

inside her mouth

散發出難聞的氣味。

that had actually cracked off her entire lower jaw.

腫瘤使她的整個下顎崩塌，

She hadn't eaten for days.

她好幾天沒吃東西。

Her guts were swimming with parasitic worms.

她的肚子裏有許多寄生蟲，

Her body was riddled with secondary tumors.

她的身上長滿了繼發性腫瘤，

And yet, she was feeding three little baby Tasmanian devils

但是，她還在餵她口袋裏的

in her pouch.

三個小寶貝。

Of course, they died along with the mother.

當然，在母親去世後，牠們也跟着去了。

They were too young to survive without their mother.

因為牠們還太小，無法離開母親。

In fact, in the area where she comes from,

實際上在她生活的地區

more than 90 percent of the Tasmanian devil population

已有百分之九十以上的塔司馬尼亞惡魔死於

has already died of this disease.

這種疾病。

Scientists around the world

全世界的科學傢

were intrigued by this cancer,

都對這種癌症很感興趣，

this infectious cancer,

這種傳染性的癌症

that was spreading through the Tasmanian devil population.

在塔司馬尼亞惡魔中傳播，

And our minds immediately turned to cervical cancer in women,

讓我們不由立即想起子宮頸癌

which is spread by a virus,

也是由病毒傳播的，

and to the AIDS epidemic,

還有愛滋病的傳播

which is associated with a number of different types of cancer.

和好幾種不同類型的癌症有關。

All the evidence suggested that this devil cancer

所有的證據都表明塔司馬尼亞惡魔所得的癌症

was spread by a virus.

是由病毒傳染的。

However, we now know -- and I'll tell you right now --

但是，我們現在知道－我現在就告訴各位：

that we know that this cancer is not spread by a virus.

這種癌症並非由病毒傳染。

In fact, the infectious agent of disease in this cancer

實際上，這種癌症的傳染性病原體

is something altogether more sinister,

非常兇險，

and something that we hadn't really thought of before.

而且是我們以前甚至不曾想到的。

But in order for me to explain what that is,

但是為了向各位解釋它究竟是什么，

I need to spend just a couple of minutes

我需要花一兩分鐘的時間，

talking more about cancer itself.

談談癌症本身。

Cancer is a disease

癌症這種疾病

that affects millions of people around the world every year.

每年感染全球數百萬人

One in three people in this room

在座的三分之一

will develop cancer at some stage in their lives.

將會在今後人生的不同階段患上癌症

I myself had a tumor removed from my large intestine

我自己就曾動過大腸腫瘤切除手術，

when I was only 14.

當時我年僅14歲。

Cancer occurs

癌症的發生

when a single cell in your body

是由於體內某個細胞中

acquires a set of random mutations in important genes

的重要基因發生了一系列突變，

that cause that cell to start to produce

導致該細胞開始

more and more and more copies of itself.

不斷自我複製。

Paradoxically, once established,

矛盾的是，一旦出現這種情況，

natural selection actually favors

‘自然選擇’實際上更傾向於

the continued growth of cancer.

不斷增長的癌症。

Natural selection is survival of the fittest.

因為‘自然選擇’就是適者生存。

And when you have a population of fast-dividing cancer cells,

當你有相當數目的快速分裂的癌細胞時，

if one of them acquires new mutations,

如果其中之一發生新的突變

which allow them to grow more quickly,

而增長更為迅速

acquire nutrients more successfully,

更成功的獲得營養

invade the body,

侵入身體，

they'll be selected for by evolution.

它就會成為演變的選擇。

That's why cancer is such a difficult disease to treat.

這就是癌症如此難以治療的原因。

It evolves.

因為它會進化。

Throw a drug at it,

對它用藥，

and resistant cells will grow back.

抗性細胞會重新生長。

An amazing fact is that,

驚人的事實是，

given the right environment and the right nutrients,

如果有合適的環境和營養，

a cancer cell has the potential

一個癌細胞就有可能

to go on growing forever.

永遠生長下去。

However cancer is constrained

可是癌症

by living inside our bodies,

受到生活在我們體內的限制，

and its continued growth,

如果它繼續生長，

its spreading through our bodies

就會遍佈我們的身體

and eating away at our tissues,

啃噬我們的組織，

leads to the death of the cancer patient

導致癌症病人死亡

and also to the death of the cancer itself.

最後自己也被消滅。

So cancer could be thought of

所以癌症是一種

as a strange, short-lived, self-destructive life form --

奇怪的，短命的，自我毀滅的生命形式－－

an evolutionary dead end.

一種演化的死亡終結。

But that is where the Tasmanian devil cancer

但是塔司馬尼亞惡魔所得的癌症

has acquired an absolutely amazing

卻獲得了一種絕對神奇的

evolutionary adaptation.

進化適應。

And the answer came from studying

這個結論是來自

the Tasmanian devil cancer's DNA.

對塔司馬尼亞惡魔的癌症DNA研究。

This was work from many people,

這項研究工作有許多人參與，

but I'm going to explain it through a confirmatory experiment

但是我想通過一個驗證實驗來向大家解釋。

that I did a few years ago.

這個試驗是在好幾年前做的。

The next slide is going to be gruesome.

下一張幻燈片會很可怕。

This is Jonas.

這是喬納斯。

He's a Tasmanian devil that we found

我們發現這隻塔司馬尼亞惡魔

with a large tumor on his face.

的臉上長着巨大的腫瘤。

And being a geneticist,

我是基因學家，

I'm always interested to look at DNA and mutations.

對于DNA 和突變總是很感興趣。

So I took this opportunity

所以我抓住這個機會，

to collect some samples from Jonas' tumor

從喬納斯的腫瘤當中取樣，

and also some samples from other parts of his body.

同時也從它身體的其它部分取樣。

I took these back to the lab.

我把這些樣本帶回實驗室

I extracted DNA from them.

從中提取DNA。

And when I looked at the sequence of the DNA,

我研究喬納斯的DNA序列，

and compared the sequence of Jonas' tumor

把它的腫瘤DNA的序列

to that of the rest of his body,

和它身體其它部分作比較。

I discovered that they had a completely different genetic profile.

我發現它們的基因圖譜完全不同。

In fact, Jonas and his tumor

實際上，喬納斯和它身上的腫瘤的基因

were as different from each other

就好像妳和妳的鄰座的一樣

as you and the person sitting next to you.

完全不同。

What this told us was that Jonas' tumor

這說明喬納斯的腫瘤

did not arise from cells of his own body.

不是來自於它自身的細胞

In fact, more genetic profiling

實際上，更多的基因圖譜

told us that this tumor in Jonas

告訴我們喬納斯的這個腫瘤

actually probably first arose

最早可能是來自於

from the cells of a female Tasmanian devil --

一隻母惡魔的細胞，

and Jonas was clearly a male.

而喬納斯是公的。

So how come

那麼，為什么

a tumor that arose from the cells of another individual

一個來自別人細胞的腫瘤

is growing on Jonas' face?

會長在喬納斯的臉上呢？

Well the next breakthrough

下一個突破

came from studying hundreds of Tasmanian devil cancers

來自于對于整個塔司馬尼亞地區數百隻

from all around Tasmania.

塔司馬尼亞惡魔的研究。

We found that all of these cancers

我們發現所有的癌症

shared the same DNA.

有同樣的DNA。

Think about that for a minute.

想一想吧。

That means that all of these cancers

這說明這些癌症

actually are the same cancer

實際上是來源於

that arose once from one individual devil,

一隻塔司馬尼亞惡魔，

that have broken free of that first devil's body

癌細胞突破了這隻惡魔的身體

and spread through the entire Tasmanian devil population.

傳染到整個種群。

But how can a cancer spread in a population?

可是癌症是怎樣在整個族群裡傳播的呢？

Well the final piece of the puzzle came

最後一個謎團終於解開。

when we remember how devils behave when they meet each other in the wild.

我們想起它們在野外見面時的表現。

They tend to bite each other,

它們喜歡啃咬對方

often quite ferociously and usually on the face.

常常很兇猛，而且通常是咬對方的臉。

We think that cancer cells

我們認為癌細胞

actually come off the tumor, get into the saliva.

是從腫瘤脫落，進入唾液的。

When the devil bites another devil,

當一隻惡魔咬了另一隻的時候，

it actually physically implants living cancer cells into the next devil,

實際上它把活的癌細胞移植到另一隻的體內，

so the tumor continues to grow.

由此腫瘤就繼續生長。

So this Tasmanian devil cancer

所以這隻塔司馬尼亞惡魔感染的

is perhaps the ultimate cancer.

可能就是已發展的癌症。

It's not constrained by living within the body that gave rise to it.

從而使得這種癌症不受限於在體內生長，

It spreads through the population,

而可以在整個族群中傳播。

has mutations that allow it to evade the immune system,

它的突變體使其得以避開免疫系統。

and it's the only cancer that we know of

它是我們所知道的唯一一種

that's threatening an entire species with extinction.

威脅到整個種群生存的癌症。

But if this can happen in Tasmanian devils,

但是，既然塔司馬尼亞惡魔會患上這種癌症，

why hasn't it happened in other animals

為什麼其他動物，

or even humans?

或者說人類就不會感染呢？

Well the answer is, it has.

實際上已經有了。

This is Kimbo.

這是金波，

He's a dog that belongs to a family in Mombasa in Kenya.

是一個住在肯亞盟巴撒島的家庭所養的一隻小狗。

Last year, his owner noticed some blood

去年，牠的主人發現

trickling from his genital region.

牠的生殖器部位淌血。

She took him to the vet

她帶牠去看獸醫。

and the vet discovered something quite disgusting.

而獸醫發現情況頗為糟糕。

And if you're squeamish, please look away now.

如果你覺得噁心，請不要看下面的畫面。

He discovered this,

他發現了這個，

a huge bleeding tumor

巨大的出血性腫瘤

at the base of Kimbo's penis.

長在金波的隂莖底部。

The vet diagnosed this as transmissible venereal tumor,

根據獸醫的診斷，這是傳染性花柳腫瘤

a sexually transmitted cancer

是一種犬類會經過性行為感染的

that affects dogs.

傳染性癌症。

And just as the Tasmanian devil cancer is contagious

正如塔司馬尼亞惡魔所患的癌症，

through the spread of living cancer cells,

是通過感染癌症活細胞而傳播的，

so is this dog cancer.

這隻狗也是同樣情況。

But this dog cancer is quite remarkable,

但是牠的癌症更驚人

because it spread all around the world.

因為這種癌症傳播到全世界。

And in fact, these same cells

實際上，同樣的細胞

that are affecting Kimbo here

在此感染到金波，

are also found affecting dogs

也一樣感染到

in New York City,

紐約市、

in mountain villages in the Himalayas

喜馬拉雅山村、

and in Outback Australia.

和澳洲內地的狗。

We also believe this cancer might be very old.

我們還認為這種癌症的來歷可能非常久遠。

In fact, genetic profiling tells

事實上，根據基因圖譜，

that it may be tens of thousands of years old,

這種癌症可能已有超過萬年以上的歷史。

which means that this cancer

這意味著這種癌症

may have first arisen

最早可能是

from the cells of a wolf

來自那些住在

that lived alongside the Neanderthals.

尼安德塔人聚落附近的狼群。

This cancer is remarkable.

這個癌症很驚人，

It's the oldest mammalian-derived life form that we know of.

因為這是我們迄今所知最古老的哺乳類生命，

It's a living relic

是遠古時代的

of the distant past.

活化石。

So we've seen that this can happen in animals.

我們已經看到這在動物身上發生，

Could cancers be contagious between people?

那麼癌症是否也會在人們之間傳染呢？

Well this is a question

這個問題

which fascinated Chester Southam,

吸引了50年代的

a cancer doctor in the 1950s.

一位癌症專傢－－切斯特.索思姆。

Ad he decided to put this to the test

他決定做一個試驗，

by actually deliberately inoculating people

將癌症病人的細胞

with cancer from somebody else.

注射到其他人體內。

And this is a photograph of Dr. Southam in 1957

這張照片是1957年索思姆醫生

injecting cancer into a volunteer,

將癌細胞注射到在監獄服刑

who in this case was an inmate

的志願囚犯身體的照片。

in Ohio State Penitentiary.

這是在俄亥俄州監獄。

Most of the people that Dr. Southam injected

大部分接受索思姆醫生注射的志願者

did not go on to develop cancer

沒有因注射

from the injected cells.

而產生癌症。

But a small number of them did,

但是有一小部分人則罹患了癌症。

and they were mostly people who were otherwise ill --

他們多數已患有其它疾病

whose immune systems were probably compromised.

免疫系統可能早已遭到破壞。

What this tells us,

這告訴我們

ethical issues aside,

且不討論倫理道德

is that ...

就是說...

(Laughter)

（笑）

it's probably extremely rare

癌症在人類之間傳染的

for cancers to be transferred between people.

機率或許微乎其微。

However, under some circumstances,

但是，在某些情況下，

it can happen.

確實會發生。

And I think that this is something

我覺得這是

that oncologists and epidemiologists

腫瘤學家和流行病學家

should be aware of in the future.

在今後應該關注的。

So just finally,

最後，

cancer is an inevitable outcome

癌症是

of the ability of our cells

細胞分裂

to divide

以及適應其自身環境的

and to adapt to their environments.

必然結果。

But that does not mean that we should give up hope

但是我們不應放棄

in the fight against cancer.

擊敗癌症的信心。

In fact, I believe, given more knowledge

實際上，我相信，如果我們掌握

of the complex evolutionary processes that drive cancer's growth,

更多引起癌症生長的複雜進化過程相關知識

we can defeat cancer.

我們一定能打敗癌症。

My personal aim

我個人的目標

is to defeat the Tasmanian devil cancer.

就是打敗塔司馬尼亞惡魔所患的癌症。

Let's prevent the Tasmanian devil

我們不能讓塔司馬尼亞惡魔

from being the first animal

變成第一種

to go extinct from cancer.

因癌症而滅絕的動物。

Thank you.

謝謝。

(Applause)

（掌聲）