What is leukemia? - Danilo Allegra and Dania Puggioni

翻译人员: fuyu you 校对人员: Amy H. Fann

Despite advances in medicine,

尽管医学在进步

cancer remains one of the most frightening diagnoses patients can receive.

癌症仍是患者们最怕听到的诊断结果

What makes it so difficult to cure is that it's not one illness,

使它难以治愈的原因是：它并不是一个单一的病变

but a family of over 100 diseases occurring in different types of cells.

而是在不同的细胞内发生的超过100种病变的统称

And one type of cancer has the unfortunate distinction

其中有一种癌症给儿童带来的折磨

of afflicting children more than any other type.

比其它任何一种癌症都更加难熬

This is leukemia,

那就是白血病

a cancer that begins in stem cells found in the bone marrow.

一种始于骨隧中干细胞的癌症

A stem cell is a bit like an infant,

干细胞有点儿像一个婴儿

undeveloped but possessing great potential.

还未充分发育但潜能巨大

Many stem cells specialize and become cells of organs,

许多干细胞经过分化变成器官细胞

like the liver, brain and heart.

例如肝脏、大脑和心脏

But in some tissues,

但在某些组织中

they can continue to divide into new stem cells throughout development,

它们将继续分裂产生新的干细胞

and into adulthood in order to frequently generate new cells

而后再分化成熟

and keep up with the body's needs.

以跟上身体生长发育需求

One example is the bone marrow,

其中一个例子就是骨髓

where stem cells differentiate into many types of blood cells.

其中的干细胞将分化为多种血细胞

That includes red blood cells,

包括红血球

which carry oxygen from the lungs to all tissues,

用于将氧气从肺输送到所有组织

platelets, which help stop bleeding by sticking to damaged blood vessels,

血小板，堵住受伤的血管以止血

and white blood cells,

以及白血球

which patrol the body, destroying potentially harmful invaders.

它们负责守护身体，摧毁潜在的有害入侵者

Every once in a while,

有时

something goes wrong during a stem cell's specialization process

干细胞在分化过程中会出问题

and harmful mutations occur in the cell's DNA.

细胞DNA会出现有害突变

Cells with compromised DNA are supposed to self-destruct,

受损DAN的细胞一般会凋亡

but some damaged cells ignore this order,

但有些受损细胞没有遵守这个规律

replicating uncontrollably, even as they lose their original function.

而是不受控制的不断复制

尽管它们已失去了原有的功能

These are what we know as cancer cells.

这就是我们所说的癌细胞

It is not yet clear why leukemia is the most common childhood cancer,

为什么白血病是儿童最易患的癌症还尚未知晓

but one contributing factor may be

但原因之一可能是

that leukemias are often caused by just one or two DNA modifications,

一两个DNA位点突变就能使白血病细胞产生

while most cancers require many of them,

而其他癌症则需要多个DNA位点的突变

allowing leukemias to arise faster than other types of cancer.

这就使得白血病比其他癌症发病快得多

Moreover, some DNA alterations can occur in white blood cells

此外，白细胞中某些DNA改变

during fetal development,

在胎儿时期就能发生

further increasing the risk of early leukemia.

所以增加了早期患白血病的风险

But though it affects more children than any other cancer,

尽管比其他癌症，儿童更容易得白血病

adults constitute the majority of leukemia patients overall.

但总的来说成人白血病患者还是占大多数的

Once leukemia strikes, the damaged cells reproduce in the blood and the bone marrow

患病后，受损细胞会在血液和骨髓里不断复制

until they take up all available space and resources.

直到它们侵占所有空间和资源

When the bone marrow can no longer produce

当骨髓不能产生

the required amount of functional cells,

足够数量的功能正常的细胞时

the blood becomes depleted.

血液便枯竭了

The lack of red blood cells

红血球的缺乏

means that muscles don't get enough oxygen,

意味着肌肉得不到足够的氧气

the reduced number of platelets is not sufficient to repair wounds,

血小板数量的减少也使得伤口难以修复

and the dearth of functional white blood cells impairs the immune system,

而有用白细胞的缺乏降低了免疫力

increasing the risk of infections.

增加了受感染的风险

To restore the normal function of the blood,

要重建正常的血液系统

leukemic cells have to be eliminated.

白血病细胞需要被清除

But because leukemias are not solid tumors,

但因为白血病并非实体瘤

they can't be removed surgically.

所以它无法通过手术切除

Instead, the cells are killed inside the body using various treatments

但存在许多其他方法能消灭体内的白血病细胞

that include chemotherapy,

包括化疗

a combination of drugs that destroys quickly multiplying cells.

也就是一系列药物，可杀死快速复制的细胞

Unfortunately, this has the side effect of killing healthy cells,

遗憾的是，这种疗法也会杀死健康的细胞

such as those found in hair follicles or intestines.

例如毛囊或肠道

And in some cases, the dosage required is so high

有一些情况下，化疗需要的药量很大

that it kills all cells in the bone marrow,

会杀死骨髓里全部的细胞

including stem cells.

包括干细胞

When this happens, the body is no longer able to create new blood cells on its own.

这种情况下，身体无法自己产生新的血细胞

Fortunately, outside help can come in the form of stem cells

幸运的是，干细胞可以从他人中获得

from the bone marrow of a donor.

也就是骨髓捐献者

Once transplanted into the patient,

当骨髓被移植到患者身体后

they rapidly repopulate the bone marrow and the blood.

它会迅速产生骨髓和血液

However, bone marrow transplants are a complicated process

然而，骨髓移植的过程很复杂

requiring antigen compatibility between the donor and recipient

它要求捐献者和患者间的抗原能够匹配

to keep the transplanted cells from from attacking the patient's own cells

这样才能防治移植的细胞攻击患者自身细胞

as foreign bodies.

Unlike with blood transplants,

与输血不同

there are thousands of HLA types,

HLA（人类白细胞抗原）有几千种

and even siblings and close relatives may not have compatible bone marrow.

甚至,患者与兄弟姐妹、近亲的HLA都不一定能相容

If this is the case, the search is expanded to a database

这时，就得在数据库进行搜寻

containing the genetic makeup of millions of voluntary bone marrow donors.

数据库录入了数百万骨髓捐献者的基因

The more potential donors there are,

骨髓捐献者越多

the more patients lives can be saved through successful transplants.

能通过骨髓移植被救治的患者就越多

Leukemia may be a frightening disease, but there is strength and hope in numbers.

白血病固然可怕，但全体奋斗能带来力量与希望