How does chemotherapy work? - Hyunsoo Joshua No

翻译人员: Meng Ren 校对人员: 潘 可儿

During World War I, one of the horrors of trench warfare

一战时期，有一种 黄色的有毒气体，

was a poisonous yellow cloud called mustard gas.

堪称堑壕战里，最恐怖的梦魇， 它就是“芥子毒气”。

For those unlucky enough to be exposed,

一旦不幸中招，

it made the air impossible to breathe, burned their eyes,

你将会无法呼吸， 双眼灼伤，

and caused huge blisters on exposed skin.

暴露的皮肤上长出巨大的水泡。

Scientists tried desperately to develop an antidote to this vicious weapon of war.

科学家们穷尽精力，想要研制出 能对抗这残暴武器的解毒剂。

In the process they discovered the gas was irrevocably damaging the bone marrow

在这个过程中，他们发现气体 对伤员的骨髓造成了永久性损伤，

of affected soldiers— halting its ability to make blood cells.

使它无法继续产生血细胞。

Despite these awful effects, it gave scientists an idea.

这一糟糕的结果反而 赋予了科学家们灵感。

Cancer cells share a characteristic with bone marrow: both replicate rapidly.

癌细胞和骨髓细胞有一个共同点： 它们都能快速自我复制

So could one of the atrocities of war

那么，我们能否将战争的暴行

become a champion in the fight against cancer?

变为对抗癌症的武器呢？

Researchers in the 1930s investigated this idea

1930 年代的研究学者 对这个想法进行了验证。

by injecting compounds derived from mustard gas

他们从芥子气中提取出复合物，

into the veins of cancer patients.

再注入癌症病人的静脉里。

It took time and trial and error to find treatments that did more good than harm,

通过长时间反复的试验，他们发现 这种方法利大于弊。

but by the end of World War II,

而在第二次世界大战末期，

they discovered what became known as the first chemotherapy drugs.

人们终于发现了 世界上第一种化疗药物。

Today, there are more than 100.

如今，市面上的化疗药物 高达上百种。

Chemotherapy drugs are delivered through pills and injections

患者可以选择口服或者注射，

and use "cytotoxic agents," which means compounds that are toxic to living cells.

这是一种“细胞毒剂”， 即对活细胞有毒的化合物。

Essentially, these medicines cause some level of harm to all cells in the body—

虽然，这些药物在一定程度上 会损伤身体里的所有细胞，

even healthy ones.

包括健康的。

But they reserve their most powerful effects for rapidly-dividing cells,

但当面对快速分裂的细胞时， 打击效果最佳，

which is precisely the hallmark of cancer.

而那正好是癌细胞的标志。

Take, for example, those first chemotherapy drugs,

举个例子，烷化剂是 我们发现的第一种

which are still used today and are called alkylating agents.

并且至今仍在使用的 化疗药物。

They’re injected into the bloodstream,

这是一种注射型药物，

which delivers them to cells all over the body.

被输送到所有细胞内。

Once inside, when the cell exposes its DNA in order to copy it,

当 DNA 进行自我复制时

they damage the building blocks of DNA’s double helix structure,

它将破坏 DNA 的双螺旋结构，

which can lead to cell death unless the damage is repaired.

从而杀死细胞， 除非损伤被修复。

Because cancer cells multiply rapidly,

而正因为癌细胞的繁殖速度快，

they take in a high concentration of alkylating agents,

吸引烷化剂大量涌入，

and their DNA is frequently exposed and rarely repaired.

DNA 在暴露过程中被迅速破坏， 很难自我修复。

So they die off more often than most other cells,

所以癌细胞的死亡速度 远远高于其他细胞，

which have time to fix damaged DNA

后者有足够时间 自我修复受损的 DNA，

and don’t accumulate the same concentrations of alkylating agents.

而不会累积过量的烷化剂。

Another form of chemotherapy involves compounds called microtubule stabilizers.

第二种化疗药物 含有一种“微管稳定剂”。

Cells have small tubes that assemble to help with cell division

细胞内的微管聚集后能 协助细胞分裂、

and DNA replication, then break back down.

DNA 复制，然后微管散开， 完成细胞复制。

When microtubule stabilizers get inside a cell,

微管稳定剂进入细胞后，

they keep those tiny tubes from disassembling.

它们能阻止已经 聚集的微管散开，

That prevents the cell from completing its replication, leading to its death.

从而截断细胞的复制过程， 导致细胞死亡。

These are just two examples of the six classes of chemotherapy drugs

除了上述两种， 还有另外四种化疗药物

we use to treat cancer today.

被用于现代癌症临床治疗。

But despite its huge benefits, chemotherapy has one big disadvantage:

尽管化疗有着巨大的好处， 但它有一个明显的缺点：

it affects other healthy cells in the body that naturally have to renew rapidly.

正常情况下迅速代谢的细胞 也面临着化疗的巨大杀伤力。

Hair follicles, the cells of the mouth, the gastrointestinal lining,

毛囊、口腔细胞、 胃肠黏膜、

the reproductive system, and bone marrow are hit nearly as hard as cancer.

生殖系统、甚至骨髓， 统统都遭受了无差别攻击。

Similar to cancer cells, the rapid production of these normal cells

这些正常细胞 和癌细胞一样繁殖迅速，

means that they’re reaching for resources more frequently—

也就意味着 它们将消耗更多的营养，

and are therefore more exposed to the effects of chemo drugs.

与血管内的化疗药物的 反应也更加频繁。

That leads to several common side effects of chemotherapy,

从而导致化疗的各项副作用，

including hair loss, fatigue, infertility, nausea, and vomiting.

包括脱发、疲劳、不孕不育、 恶心、呕吐等。

Doctors commonly prescribe options to help manage these side-effects,

通常，为了缓解不适， 医生会给患者开一些药

such as strong anti-nausea medications.

比如强效的止吐药。

For hair loss, devices called cold caps can help lower the temperature

有一种冷却帽， 专门用于防止脱发。

around the head and constrict blood vessels,

它能降低头皮温度， 收缩血管，

limiting the amount of chemotherapy drugs that reach hair follicles.

减少化疗药物与毛囊的接触。

And once a course of chemo treatment is over,

当一个疗程的化疗结束后，

the healthy tissues that’ve been badly affected by the drug will recover

之前受损严重的皮肤组织 将恢复健康，

and begin to renew as usual.

重新开始正常的新陈代谢。

In 2018 alone, over 17 million people world-wide received a cancer diagnosis.

仅在 2018 年，全世界就有超过 1700 万人被确诊癌症。

But chemotherapy and other treatments have changed the outlook for so many.

幸好，化疗以及其他治疗手段 为我们带来了希望的曙光。

Just take the fact that up to 95% of individuals with testicular cancer

超过 95% 的睾丸癌患者重获健康，

survive it, thanks to advances in treatment.

而这多亏了医学的进步。

Even in people with acute myeloid leukemia— an aggressive blood cancer—

即使像急性髓系白血病 这种严重的血癌，

chemotherapy puts an estimated 60% of patients under 60

在接受第一个阶段的化疗后， 约 60% 六十岁以下的

into remission following their first phase of treatment.

患者的病情得到了缓解。

Researchers are still developing more precise interventions

学者们还在继续研究更准确的，

that only target the intended cancer cells.

只针对癌细胞的干预方式，

That’ll help improve survival rates while leaving healthy tissues

以期在提高存活率的同时，

减轻对健康组织的伤害，

with reduced harm,

making one of the best tools we have in the fight against cancer even better.

以改进我们拥有的 最好的抗癌工具之一。