A blood test for cancer can now show where in the body a tumour is growing, without the need for a painful biopsy.
一种癌症的血液检测方法可以测出肿瘤在体内生长的位置，而不需要进行活组织检测。
'Liquid biopsies' are hoped to revolutionise cancer treatment, by identifying people with slow-growing tumours and those most in danger. They work by detecting the DNA released by dying tumour cells.
人们希望通过“血液活检”发现人体内的慢性肿瘤和最危险的肿瘤，从而彻底改变癌症的治疗方式。其原理是检测死亡肿瘤细胞释放的DNA。
Now, for the first time, US scientists can also pinpoint the part of the body affected.
现在，美国科学家还首次实现精准定位患病的部位。
That is because the normal cells killed off by cancer also release DNA into the bloodstream, which has its own unique signature.
这是因为被癌症杀死的正常细胞也会将DNA释放到血液中，这些DNA有其独特的特征。
A team from the University of California San Diego have found the DNA patterns for 10 different types of tissue, including from the liver, lung and kidneys.
加利福尼亚大学圣地亚哥分校的一个研究小组发现了肝、肺、肾等10种不同人体组织的DNA模式。
It means cancer patients who have symptoms shared across different types of cancer, such as bloating or sudden weight loss, could in future be diagnosed quickly and easily without needing a biopsy to remove part of an organ for testing.
这意味着未来人们可以简单快速确诊出现腹胀、体重骤减等癌症一般症状的病患，而无需切除器官的一部分用来进行活组织检测。
Dr Catherine Pickworth, Cancer Research UK's science information officer, said: 'A biopsy can be invasive and unpleasant to go through, while any operation with an anaesthetic is risky.
英国癌症研究所科学信息主任凯瑟琳•皮克沃思博士称：“开刀进行活组织检测是有创的，而任何使用麻醉剂的手术都是有风险的。
This is potentially safer if it can be effective, which is why people are focusing on liquid biopsies.
如果血液检测有效，那么这种方法会更安全，这也正是人们关注血液活检的原因。
Finding new ways to detect and treat cancer at an early stage is vital to help more people survive the disease. Looking for the DNA of cancer cells in the blood is an exciting idea, and this encouraging new approach might help reveal the location of tumours. '
寻找在初期检测和治疗癌症的新方法对拯救更多的癌症患者至关重要。寻找血液中的癌细胞DNA是一个激动人心的想法，而且这种新方法可能有助于揭示肿瘤的位置。”
The US researchers, whose study is published in Nature Genetics, analysed samples of tumours and blood samples from cancer patients to find markers for different organs in the blood.
美国研究人员分析了癌症患者的肿瘤样本和血液样本，从而找出血液中不同器官的标记。他们将研究成果发表在了《自然遗传学》杂志上。
They created a DNA database for the liver, intestine, colon, lung, brain, kidney, pancreas, spleen, stomach and blood.
研究人员创造了一个肝脏、肠道、结肠、肺、脑、肾、胰腺、脾、胃以及血液的DNA数据库。
Now the bioengineers know the normal cells, killed off when tumour cells compete with them for space and nutrients, also release a DNA signature, called CpG methylation haplotypes.
现在，这些生物工程师们发现在与肿瘤细胞争夺空间及营养物质时被杀死的正常细胞也释放一种DNA信号，叫做CpG甲基化单体。
They were able to test which organ they came from by checking their diagnoses back against the cancer patients.
他们可以通过对比癌症患者之前的诊断检测出这些细胞来自哪个器官。
The researchers screened blood samples from individuals with and without tumours, looking for signals of the cancer markers and the tissue-specific methylation patterns.
研究人员通过检测患有癌症和健康的个体的血液样本，寻找肿瘤标志物的信号以及组织特异的甲基化模式。
The test works like a dual authentication process, with the combination of both signals required to assign a positive match.
这个测试就像是一个双重认证过程，两种信号的组合需要正向匹配。
The author added: 'This a proof of concept. To move this research to the clinical stage, we need to work with oncologists to further optimise and refine this method.'
研究作者称：“这还是概念验证。要将该研究应用于临床，我们需要和肿瘤专家进一步完善和优化这个方法。”