经济学人下载:癌症预防 灵丹妙药

Technology Prevention of cancer Wonder drug
科技 癌症预防 灵丹妙药

Aspirin continues to amaze
阿司匹林：继续给你惊喜

FOR thousands of years aspirin has been humanity's wonder drug.
阿司匹林作为人类的特效药实际上已存在了数千年。

Extracts from the willow tree have been used for pain relief in folk medicine since the time of the ancient Greeks.
早在古希腊时期，民间就使用柳树的提取物作为药物来缓解疼痛。

By 1897 a synthetic derivative (acetyl salicylic acid) of the plant's active ingredient (salicin) was created.
到了1897年，一种取自柳树的活性成分柳醇（水杨苷）的衍生合成物——乙酰水杨酸诞生了。

This allowed aspirin to become the most widely used medicine in the world.
这使得阿司匹林成为世界上使用最为广泛的药物。

In recent years its benefits as a blood-thinning drug have led to it being prescribed in low doses of around 50mg to reduce deaths from stroke and heart attack.
因其具有稀释血液的作用，近年来医界已使用50mg左右的低剂量阿司匹林来降低中风和心脏病带来的死亡危险。

There were also hints that aspirin may help prevent some cancers.
也有消息称阿司匹林还可预防某些癌症，

But these were mostly based on observational studies, which can be misleading.
但大多都是基于观测研究得来的，不可全信。

The gold standard of scientific evidence is the randomised controlled trial, preferably one with a lot of people and held over a long time.
获得科学证明的最佳标准就是随机临床试验，最好是长期且有大批人参加的。

The results of just such a trial, published in the Lancet, suggest that aspirin is indeed an astonishing drug.
正是这样一个试验，发表在Lancet上的结果表明，阿司匹林的确是一种令人称奇的药物。

Peter Rothwell at the John Radcliffe Hospital in Oxford and his colleagues looked at deaths due to cancers during and after randomised trials of daily aspirin.
牛津约翰拉德克利夫医院的Peter Rothwell与其同事们以随机试验的方式观察了罹患癌症的病人在每日使用阿司匹林期间与其后的状况。

The trials had actually been started to look at how useful aspirin was for preventing heart attacks and strokes. Nevertheless, the data from the 25,570 patients enrolled in eight trials was also revealing about cancer.
实际上开始试验的目的是为了查看阿司匹林对于预防心脏病与中风的效果，尽管如此，从25,570名病人身上收集的8个试验的数据同样表明了这种药物对癌症的作用。

In trials lasting between four and eight years, the patients who had been given aspirin were 21% less likely to die from cancer than those who had been given a placebo.
在长达四年到八年不等的试验过程中，使用阿司匹林的病人，因癌症死亡的概率比使用安慰剂的病人要低21%。

These results were based on 674 cancer deaths, so are unlikely to represent the kind of statistical oddity that can beset studies on cancer risks that sometimes create headlines.
这一结果是基于674名罹患癌症面临死亡的病人，因而对于那种围绕研究癌症风险给人提前判死刑（缓刑）的概率学数据，还不大能拉得上关系。

The benefits of aspirin were also apparent many years after the trials had ended.
阿司匹林的良性作用在试验结束多年后仍明显存在于用药人群身上。

After five years, death rates for all cancers fell by 35% and for gastrointestinal cancers by 54%.
试验结束五年后，所有癌症患者的死亡率下降了35%，肠胃癌症病人更是下降了54%。

A long-term follow-up of patients showed that the 20-year risk of cancer death remained 20% lower in those who had taken aspirin.
一项长期的跟踪观察试验表明，在患有癌症，并且有20年的"缓刑期"的人群当中，服用阿司匹林的人其死亡率要低20%。

The study revealed that the effect takes time to accrue, so aspirin must be taken over a long period.
这一试验说明了阿司匹林的药效需要经过长时间的累积，因此阿司匹林需长期服用才有效果。

The latent period for improving oesophageal, pancreatic, brain and lung cancer was about five years of aspirin taking on a daily basis.
对于食道癌、胰脏癌、脑癌及肺癌，大约需持续5年每日服用阿司匹林才可见效；

For stomach and colorectal cancer the effects took ten years and for prostate cancer about 15 years.
对胃癌、直肠癌，需10年；前列腺癌则需约15年。

The means by which aspirin prevents cancer is not well understood. It is believed that it inhibits an enzyme that promotes cell proliferation in tumours.
阿司匹林预防癌症的机理现在还不明了，但人们普遍认为，它通过抑制一种有助于癌细胞繁殖的酶而起效。

The researchers also found that small daily doses of aspirin were enough, and that taking more than 75mg conferred no additional benefits.
研究者还发现，每日接受小剂量的阿司匹林就已足够，超过75毫克并没有过多的效用。

Those starting on aspirin in their late 40s or 50s benefit most.
而服用者当中，接近50岁或50多岁的人收效最好。

Current guidelines on using aspirin for reducing the chances of a stroke or heart attack rightly warn of the small risk of ulcers and of dangerous bleeding in the stomach.
目前在服用阿司匹林以降低中风或心脏病风险时，用药说明明确指出了其中存在较低的可能引起溃疡或危险性胃出血的风险。

These guidelines will probably have to be revised given the new findings.
估计这类说明需要将那些最新发现加上去了。

However, it remains unlikely that popping aspirin will be recommended for everyone like a vitamin supplement.
但是，还是不大可能推荐大家像嗑维生素片一样嗑阿司匹林。

Aspirin is a highly cost-effective treatment: taking it for five to ten years easily beats initiatives to screen for breast and prostate cancers.
服用阿司匹林是一种高性价比的治疗方式：服用阿司匹林五到十年绝对强过定期去做乳腺癌或前列腺癌的仪器检查。

To put it another way, ask yourself what a pharmaceuticals firm might charge for a drug that would reduce the chance of death by cancer by 20%—and then note that 100 days' supply of low-dose aspirin can cost less than a dollar.
换个说法就是：你想把患癌症死亡的概率降低20%，只需每日服用低剂量的阿司匹林，而每100天你只需向药商付不到1美元。

By anyone's measure, that is a bargain.
还有比这更划算的事吗？相信对任何人而言，这都再便宜不过了。