Then that cell divides and we are two cells, then four, then eight.

然後我們的細胞分裂成兩個，接著四個，再來八個。

Cells form tissues, tissues form organs, organs form us.

細胞構成組織，組織構成器官，而器官組成我們。

These cell divisions, by which we go from a single cell to 100 trillion cells, are called growth.

細胞分裂讓我們從單一細胞，變成一百兆個細胞，這就是生長。

And growth seems like a simple thing because when we think of it, we typically think of someone getting taller or, later in life, wider, but to cells, growth isn't simple.

生長這件事看似簡單，因為當我們想到它時，我們通常聯想到長高或長胖，但對細胞而言，生長並非如此單純。

Cell division is an intricate chemical dance that's part individual, part community-driven.

細胞分裂是一場複雜，而精密的化學之舞。一部份在細胞本身，另一部份則受所處群落影響。

And in a neighborhood of 100 trillion cells, sometimes things go wrong.

而在這個由一百兆細胞組成的社群中，難免有出錯的時候。

Maybe an individual cell's set of instructions, or DNA, gets a typo, what we call a mutation.

可能是細胞內的指令或 DNA 出了錯，這就是所謂的突變。

Most of the time, the cell senses mistakes and shuts itself down, or the system detects a troublemaker and eliminates it.

通常細胞能偵測錯誤並自我了斷，或由系統偵測到麻煩製造者，並消除它。

But, enough mutations can bypass this fail-safes, driving the cell to divide recklessly.

但如果有突變通過這些保護機制，就會造成細胞毫無節制的分裂下去。

That one rogue cell becomes two, then four, then eight.

一個細胞瘋狂的分裂成兩個、四個，到八個。

At every stage, the incorrect instruction are passed along to the cells' offspring.

在每個階段，錯誤的訊息都會被傳遞給子細胞。

Weeks, months, or years after that one rogue cell transformed, you might see your doctor about a lump in your breast.

在這個惡性細胞轉型的幾週、幾月，甚至幾年後，你可能就會因乳房硬塊去看醫生。

Difficulty going to the bathroom could reveal a problem in your intestine, prostate, or bladder.

如廁困難可能表示你的腸道、前列腺、或是膀胱出了問題。

Or, a routine blood test might count too many white cells or elevated liver enzymes.

也可能在例行性的驗血中，發現白血球數過高或肝臟酵素升高。

Your doctor delivers the bad news: It's cancer.

醫師就會告訴你這個壞消息：你得了癌症。

From here your strategy will depend on where the cancer is and how far it's progressed.

你所採用的療程會依據病灶及惡化程度而有所不同。

If the tumor is slow-growing and in one place, surgery might be all you need, if anything.

若腫瘤成長速度慢且集中於一處，必要時手術切除即可。

If the tumor is fast-growing or invading nearby tissue, your doctor might recommend radiation or surgery followed by radiation.

若腫瘤成長速度快且入侵到鄰近組織，醫生可能會建議使用放射線治療或在手術後再以放射線治療。

If the cancer has spread, or if it's inherently everywhere like a leukemia, your doctor will most likely recommend chemotherapy or a combination of radiation and chemo.

如果癌細胞已擴散，或像是血癌一般存在身體各處，醫生最可能推薦化學療法，或結合放射線療法和化療。

Radiation and most forms of chemo work by physically shredding the cells' DNA or disrupting the copying machinery.

放射線和大部份化療的作用機制是以物理方法破壞細胞 DNA 或干擾細胞複製機制。

But neither radiation nor chemotherapeutic drugs target only cancer cells.

但不論放射線治療或化學療法都無法只針對癌細胞。

Radiation hits whatever you point it at, and your blood stream carries chemo-therapeutics all over your body.

放射線會攻擊任何被照射的地方，而血液會將化療藥物運送到身體各處。

So, what happens when different cells get hit?

那這對各種細胞又會有什麼影響呢？

Let's look at a healthy liver cell, a healthy hair cell, and a cancerous cell.

讓我們看看健康的肝細胞、健康的毛髮細胞和癌細胞吧！

The healthy liver cell divides only when it is stressed; the healthy hair cell divides frequently; and the cancer cell divides even more frequently and recklessly.

健康的肝細胞僅在受到壓力時分裂；健康的毛髮細胞分裂頻繁；而癌細胞分裂更加頻繁，也更不受控制。

When you take a chemotherapeutic drug, it will hit all of these cells.

服用化療藥物時，藥物會影響所有細胞。

And remember that the drugs work typically by disrupting cell division.

請注意藥物作用是干擾細胞分裂。

So, every time a cell divides, it opens itself up to attack, and that means the more frequently a cell divides, the more likely the drug is to kill it.

所以，每一次細胞分裂都會讓自身受到藥物影響，這表示分裂越頻繁的細胞，越容易被藥物毒殺。

So, remember that hair cell?

還記得毛髮細胞嗎？

It divides frequently and isn't a threat.

它經常分裂但對人體不構成威脅。

And, there are other frequently dividing cells in your body like skin cells, gut cells, and blood cells.

而且人體中還有其他經常在分裂的細胞諸如：皮膚細胞、腸細胞和血球。

So the list of unpleasant side effects of cancer treatment parallels these tissue types:

所以在抗癌藥物的副作用項目中，可以對應到這些組織：

hair loss, skin rashes, nausea, vomiting, fatigue, weight loss, and pain.

掉髮、皮膚起疹、噁心、嘔吐、倦怠、體重減輕和疼痛。

That makes sense because these are the cells that get hit the hardest.

這很合理，因為這些都是受藥物影響最多的細胞。

So, in the end, it is all about growth.

到頭來，一切都和生長有關。

Cancer hijacks cells' natural division machinery and forces them to put the pedal to the metal, growing rapidly and recklessly.

癌症挾持了細胞自然的分裂機制，並迫使其走向極端，在毫無限制的狀況下快速生長。

But, using chemotherapeutic drugs, we take advantage of that aggressiveness, and we turn cancer's main strength into a weakness.

但是，化療藥物充分利用癌細胞快速分裂的特性，並將它的長處轉換成了弱點。