Could a breathalyzer detect cancer? - Julian Burschka

譯者: Lilian Chiu 審譯者: Harper Chang

How is it that a breathalyzer can measure the alcohol content in someone’s blood,

為什麼酒測器可以 單單根據一個人的呼氣，

在他喝完酒的幾小時後， 還能測量出血液中的酒精濃度？

hours after they had their last drink, based on their breath alone?

Exhaled breath contains trace amounts of hundreds, even thousands,

在呼出的氣體中，含量達到 可追蹤標準的揮發性有機化合物

of volatile organic compounds:

就有數百種甚至數千種：

small molecules lightweight enough to travel easily as gases.

它們是小型分子，輕到 能以氣體的方式輕鬆移動。

One of these is ethanol, which we consume in alcoholic drinks.

其中一種是乙醇， 我們會從酒精性飲料喝到它。

It travels through the bloodstream to tiny air sacs in the lungs,

它會通過血流， 到達肺中的小氣囊，

passing into exhaled air at a concentration 2,000 times lower,

進入到呼出的氣體當中，

此時的濃度比在血液中時 平均要低兩千倍。

on average, than in the blood.

When someone breathes into a breathalyzer,

當一個人對著酒測器呼氣，

the ethanol in their breath passes into a reaction chamber.

呼吸中的乙醇就會 進入一個反應室中。

There, it’s converted to another molecule, called acetic acid,

在那裡，乙醇會被轉換成 另一種分子，叫做乙酸，

in a special type of reactor that produces an electric current during the reaction.

在特殊的反應裝置中， 反應過程會產生出電流。

The strength of the current indicates the amount of ethanol

電流的強度表示 呼吸氣體樣本中的乙醇量，

in the sample of air, and by extension in the blood.

由此算出血液中的量。

In addition to the volatile organic compounds like ethanol

除了我們從食物和飲料中

we consume in food and drink,

取得的揮發性有機 化合物，比如乙醇，

the biochemical processes of our cells produce many others.

我們細胞的生化過程也會產生 許多其他揮發性有機物。

And when something disrupts those processes, like a disease,

當那些過程被比如疾病給打斷，

the collection of volatile organic compounds in the breath

從呼吸中收集到的 揮發性有機化合物

may change, too.

也有可能改變。

So could we detect disease by analyzing a person’s breath,

所以，我們能不能透過分析 呼吸來偵測一個人的疾病，

without using more invasive diagnostic tools

而不用更侵入性的診斷工具

like biopsies, blood draws, and radiation?

如切片檢查法、抽血和放射線？

In theory, yes,

理論上可行，

but testing for disease is a lot more complicated than testing for alcohol.

但檢測疾病比檢測酒精複雜許多。

To identify diseases,

要辨識出疾病，

researchers need to look at a set of tens of compounds in the breath.

研究者需要檢視 呼吸中數十種化合物。

A given disease may cause some of these compounds

某種疾病可能會造成 當中某些化合物

to increase or decrease in concentration, while others may not change—

濃度增加或減少， 其他的則沒改變。

the profile is likely to be different for every disease,

每一種疾病的特徵都不同，

and could even vary for different stages of the same disease.

就連同一種疾病，在不同階段 呈現的狀況也不同。

For example, cancers are among the most researched candidates

比如，最常被研究的

呼吸分析診斷候選 疾病之一是癌症。

for diagnosis through breath analysis.

One of the biochemical changes many tumors cause

許多腫瘤會造成的 其中一種生化改變

is a large increase in an energy-generating process

就是醣酵解大量增加，

它是一種產生能量的過程。

called glycolysis.

Known as the Warburg Effect,

這就是所謂的瓦氏效應，

this increase in glycolysis results in an increase of metabolites like lactate

醣酵解的增加會導致

代謝物如乳酸鹽的增加，

which in turn can affect a whole cascade of metabolic processes

它們就有可能會再影響 整個一連串的代謝過程，

and ultimately result in altered breath composition,

最後，會造成呼吸中的成分改變，

possibly including an increased concentration of volatile compounds

可能包括揮發性有機化學物

such as dimethyl sulfide.

如二甲硫醚的濃度增加。

But the Warburg Effect is just one potential indicator of cancerous activity,

但瓦氏效應只是癌症 活動的一種可能指標，

and doesn’t reveal anything about the particular type of cancer.

且它沒有任何資訊 能指出是哪一種癌症。

Many more indicators are needed to make a diagnosis.

還需要更多指標才能做出診斷。

To find these subtle differences,

為了找出這些微小的差異，

researchers compare the breath of healthy people

研究者比較健康受試者的呼吸

with the breath of people who suffer from a particular disease

和特定疾病病人有什麼不同，

using profiles based on hundreds of breath samples.

比較的基礎是數百件 呼吸樣本的特徵。

This complex analysis requires a fundamentally different,

這種複雜分析所需要的感測器 必須要有更多功能，

more versatile type of sensor from the alcohol breathalyzer.

與酒測器有很大不同。

There are a few being developed.

目前有幾種在開發中。

Some discriminate between individual compounds

有些裝置區別不同化合物的方式

by observing how the compounds move through a set of electric fields.

是觀察化合物如何 在一組電場中移動。

Others use an array of resistors made of different materials

有些裝置則是用 不同材料製成的電阻器，

that each change their resistance when exposed to a certain mix

每個都會在接觸到揮發性 有機化合物的某種混合時

of volatile organic compounds.

改變其電阻。

There are other challenges too.

還有其他的困難。

These substances are present at incredibly low concentrations—

這些物質出現的濃度非常低——

typically just parts per billion,

通常都是用分率來計算，

much lower than ethanol concentrations in the breath.

比呼吸中的乙醇濃度還要低很多。

Compounds’ levels may be affected by factors other than disease,

化合物的量可能會受到 疾病以外的其他因子影響，

including age, gender, nutrition, and lifestyle.

包括年齡、性別、 營養，以及生活方式。

Finally, there’s the issue

最後，還有一個問題：如何區別出

of distinguishing which compounds in the sample

樣本中的哪些化合物 是在病人體內產生的，

were produced in the patient’s body

and which were inhaled from the environment

哪些是在檢測前沒多久 從環境中吸入的。

shortly before the test.

Because of these challenges, breath analysis isn’t quite ready yet.

因為有這些困難， 呼吸分析還沒有成熟。

But preliminary clinical trials on lung, colon,

但針對肺、結腸，及其他癌症的 初步臨床試驗

and other cancers have had encouraging results.

顯現出十分讓人振奮的結果。

One day, catching cancer early might be as easy as breathing in and out.

也許有一天，單靠吸氣吐氣 就可以發現癌症了。