Why is it so hard to cure cancer? - Kyuson Yun

譯者: Helen Chang 審譯者: S Sung

Why is it so difficult to cure cancer?

為什麼癌症如此難治癒？

We've harnessed electricity,

我們駕馭電力

sequenced the human genome,

為人類基因組排序

and eradicated small pox.

並滅絕了天花

But after billions of dollars in research,

但花費數十億美元研究後

we haven't found a solution for a disease that affects more than 14 million people

我們還沒有找到解決方案

它在每一時間點影響到 1400 多萬人和他們的家人

and their families at any given time.

Cancer arises as normal cells accumulate mutations.

正常細胞積累突變而出現癌症

Most of the time, cells can detect mutations or DNA damage

多數時候細胞能檢測到 突變或 DNA 的損傷

and either fix them or self destruct.

修復它們或讓它們自毀

However, some mutations allow cancerous cells to grow unchecked

但是一些突變 讓癌變的細胞增長不受限制

and invade nearby tissues,

並侵入附近的組織

or even metastasize to distant organs.

甚至轉移到遠處的器官

Cancers become almost incurable once they metastasize.

一旦癌症轉移就變得幾乎無法治癒

And cancer is incredibly complex.

而癌症非常複雜

It's not just one disease.

這不只是一種疾病

There are more than 100 different types

它有超過 100 種不同的類型

and we don't have a magic bullet that can cure all of them.

我們沒有仙丹妙藥能治癒所有的癌症

For most cancers,

對於大多數癌症

treatments usually include a combination of surgery to remove tumors

治療通常結合了切除腫瘤的手術

and radiation and chemotherapy to kill any cancerous cells left behind.

和放療、化療以殺死 任何殘留的癌細胞

Hormone therapies,

激素療法

immunotherapy,

免疫療法

and targeted treatments tailored for a specific type of cancer

以及針對特定類型的癌症 量身定做的治療

are sometimes used, too.

有時也被採用

In many cases, these treatments are effective

在許多情況下這些治療有效

and the patient becomes cancer-free.

使病人沒了癌症

But they're very far from 100% effective 100% of the time.

但是它們離百分之百有效 和總是有效還遠得很

So what would we have to do to find cures for all the different forms of cancer?

那我們怎能找到 治療所有癌症的方法呢？

We're beginning to understand a few of the problems

我們開始了解

科學家將不得不解決的一些問題

scientists would have to solve.

First of all, we need new, better ways of studying cancer.

首先，我們需要新的 更好的方法來研究癌症

Most cancer treatments are developed using cell lines grown in labs

大部分的癌症治療法 用生長在實驗室的細胞來開發

from cultures of human tumors.

是用人類腫瘤培養出來的細胞

These cultured cells have given us critical insights

這些培養的細胞提供我們

about cancer genetics and biology,

瞭解癌症遺傳學和生物學的重要見解

but they lack much of the complexity of a tumor in an actual living organism.

但它們缺乏實際活在 有機體中的腫瘤的複雜性

It's frequently the case that new drugs, which work on these lab-grown cells,

通常在實驗室生長的細胞上 開發出來的新藥

will fail in clinical trials with real patients.

將會在臨床試驗真正的病人時失敗

One of the complexities of aggressive tumors

侵略性腫瘤的複雜性之一

is that they can have multiple populations of slightly different cancerous cells.

是它們有多種略有不同的癌細胞

Over time, distinct genetic mutations accumulate in cells

與時漸進，細胞在腫瘤的不同部位 積累了不同的基因突變

in different parts of the tumor, giving rise to unique subclones.

產生獨特的亞複製

For example, aggressive brain tumors called glioblastomas

例如稱為膠質母細胞瘤的惡性腦腫瘤

can have as many as six different subclones in a single patient.

在同一個病人身上可能會出現 多達六種不同的亞克複製

This is called clonal heterogeneity,

這被稱為「遺傳異質性」

and it makes treatment difficult because a drug that works on one subclone

使得治療變得困難 因為在一個亞複製上有效的藥物

may have no effect on another.

可能對另一個完全沒有作用

Here's another challenge.

還有另一個挑戰

A tumor is a dynamic interconnected ecosystem

腫瘤是個動態互聯的生態系統

where cancer cells constantly communicate with each other

在那裡的癌細胞不斷相互溝通

and with healthy cells nearby.

並與附近的健康細胞溝通

They can induce normal cells to form blood vessels that feed the tumor

它們能誘使正常細胞 形成餵養腫瘤的血管

and remove waste products.

並搬走廢物

They can also interact with the immune system

它們也能與免疫系統互動

to actually suppress its function,

實際上壓制了免疫功能

keeping it from recognizing or destroying the cancer.

使其無法識別或摧毀癌症

If we could learn how to shut down these lines of communication,

如果我們學會如何關閉這些溝通渠道

we'd have a better shot at vanquishing a tumor permanently.

就更能有效地永久擊敗腫瘤

Additionally, mounting evidence suggests

另外，越來越多的證據表明

we'll need to figure out how to eradicate cancer stem cells.

我們需要弄清楚 如何根除「癌症幹細胞」

These are rare but seem to have special properties

癌症幹細胞很罕見 但似乎有著特殊的屬性

that make them resistant to chemotherapy and radiation.

使它們能阻擋化療和放療

In theory, even if the rest of the tumor shrinks beyond detection during treatment,

理論上說，即使其餘的腫瘤 被治療到檢測不出來

a single residual cancer stem cell could seed the growth of a new tumor.

一個殘餘的癌症幹細胞 能再長成新腫瘤

Figuring out how to target these stubborn cells

弄清楚如何針對這些頑固的細胞

might help prevent cancers from coming back.

可能有助於預防癌症復發

Even if we solved those problems, we might face new ones.

即使我們解決了這些問題 我們可能會面臨新的問題

Cancer cells are masters of adaptation,

癌細胞是適應的專家

adjusting their molecular and cellular characteristics to survive under stress.

調整它們的分子和細胞特性 以在壓力下生存

When they're bombarded by radiation or chemotherapy,

當他們被輻射或化療轟炸時

some cancer cells can effectively switch on protective shields

有些癌細胞可以有效地打開防護罩

against whatever's attacking them by changing their gene expression.

通過改變基因的方式 來抵抗任何對它們的攻擊

Malignant cancers are complex systems that constantly evolve and adapt.

惡性腫瘤是不斷進化 和適應的複雜系統

To defeat them, we need to find experimental systems

要打敗他們，我們需要找到

that match their complexity,

與其複雜性相匹配的實驗系統

and monitoring and treatment options that can adjust as the cancer changes.

和可以隨著癌症的變化 而調整的監測、治療方案

But the good news is we're making progress.

好消息是我們正取得進展

Even with all we don't know,

即使我們仍有那麼多未知

the average mortality rate for most kinds of cancer

大多數癌症的平均死亡率

has dropped significantly since the 1970s and is still falling.

自 1970 年代以來顯著下降 並且仍持續下降

We're learning more every day,

我們每天都學更多

and each new piece of information gives us one more tool to add to our arsenal.

並且每條新的訊息 加一件新的工具到我們的武器庫中