患癌只因运气不佳？

Most types of cancer can be put down to bad luck rather than risk factors such as smoking, a study has suggested.

研究显示，大多数类型的癌症可以归结为运气不好，而非吸烟等风险因素所致。

A US team were trying to explain why some tissues were millions of times more vulnerable to cancer than others.

美国的一个研究团队试图对人体内部分细胞组织的癌变倾向相比同类大上数百万倍的现象作出解释。

The results, in the journal Science, showed two thirds of the cancer types analysed were caused just by chance mutations rather than lifestyle.

研究结果表明三分之二的癌症种类是由潜在的突变风险引起，而非生活方式。这一结果刊登在《科学》杂志上。

However some of the most common and deadly cancers are still heavily influenced by lifestyle.

不过一些常见的癌症和致死率极高的癌症在很大程度上依然受生活方式的影响。

And Cancer Research UK said a healthy lifestyle would still heavily stack the odds in a person's favour.

英国癌症研究（Cancer Research UK）表示健康的生活方式依然能够帮助我们降低患癌的风险。

Time to throw caution to the wind?

我们可以尽情享乐了吗？

So is it time to light-up, drink and eat what you want without a care in the world?

这是否意味着我们可以放下顾虑尽情享乐呢？

It won't come as a surprise that the answer is no.

不用说答案当然是否定的。

All cancer has an element of chance - a roll of the dice that decides whether your DNA acquires a mutation that leads to cancer.

所有癌症都有命中的可能——就像投骰子一样，它能决定你的DNA是否会出现导致癌症的突变。

The study shows that two thirds of cancer types are simply chance.

美国的研究团队发现三分之二的癌症仅仅是凑巧发生的。

But the remaining third are still heavily influenced by the choices we make.

而剩下的三分之一依然取决于我们自己的选择。

Too much booze, time in the sun or being overweight mean we are playing with loaded dice and the odds are not in our favour.

酗酒、暴晒、超重很可能会使我们投出的骰子停在患癌的一面，避免癌症的胜算将不在我们这边。

Remember smoking accounts for a fifth of all cancers worldwide.

我们不能忘记全球五分之一的癌症是由吸烟引起的。

These findings are a reminder that cancer is often just bad luck and the only option is early detection.

这些研究结果提醒我们，厄运导致患癌，唯一的补救措施是尽早发现。

But that's not an excuse to give up on those new year's resolutions already.

但是这并不能成为放弃新年计划的借口。

In the US, 6.9% of people develop lung cancer, 0.6% brain cancer and 0.00072% get tumours in their laryngeal (voice box) cartilage at some point in their lifetime.

在美国，患肺癌的人数占全国人口的6.9%，脑癌人数占0.6%，0.00072%的人曾患有喉软骨肿瘤。

Toxins from cigarette smoke could explain why lung cancer is more common.

香烟产生的毒素能够解释为什么肺癌相比其他癌症更为常见。

But the digestive system is exposed to more environmental toxins than the brain, yet brain tumours are three times as common as those in the small intestine.

尽管消化系统比之大脑更易受到周围毒素的影响，但患上脑瘤的风险却是患上小肠癌的三倍。

Root of cancer

癌症的根源

The team at Johns Hopkins University School of Medicine and Bloomberg School of Public Health believe the way tissues regenerate is the answer.

这个来自约翰霍普金斯大学彭博公共卫生医药学院的研究团队认为答案在于细胞组织的再生。

Old tired cells in the body are constantly being replaced with new ones made by dividing stem cells.

人体通过不断分裂干细胞替代衰老的细胞。

But with each division comes the risk of a dangerous mutation that moves the stem cell one step closer to being cancerous.

但是每一次的分裂都暗藏着突变风险，它会使干细胞更倾向于癌变。

The pace of turnover varies throughout the body with rapid turnover in the lining of the gut and a slower pace in the brain.

人体内各个细胞组织的分裂速度不一。肠道内的细胞更新较快，大脑内的细胞分裂速度较慢。

The researchers compared how often stem cells divided in 31 tissues in the body over a lifetime with the odds of a cancer in those tissues.

研究者们将人体内31个组织干细胞一生分裂的次数和其癌变的风险作了比较。

They concluded that two thirds of cancer types were "due to bad luck" from dividing stem cells picking up mutations that could not be prevented.

他们得出结论，三分之二的癌症类型归结于运气太差，干细胞在分裂过程中遇到了无可避免的突变情况。

These cancer types included Glioblastoma (brain cancers), small intestine cancers and pancreatic cancers.

恶性胶质瘤（脑癌）、小肠癌以及胰腺癌被包括在内。

Cristian Tomasetti, an assistant professor of oncology and one of the researchers, said a focus on prevention would not prevent such cancers.

作为研究团队一员的肿瘤学助理教授克里斯蒂安·托马赛蒂（Cristian Tomasetti）说，这些癌症无法通过预防手段来避免。

"If two thirds of cancer incidence across tissues is explained by random DNA mutations that occur when stem cells divide, then changing our lifestyle and habits will be a huge help in preventing certain cancers, but this may not be as effective for a variety of others.

“如果细胞组织中如果三分之二的癌变现象可以用干细胞分裂时的DNA突变来解释的话，那么生活方式和行为习惯的改变确实会大大降低患上某种癌症的风险。但这些改变无助于避免其他癌症类型。”

"We should focus more resources on finding ways to detect such cancers at early, curable stages."

“我们应该投入更多资源，以便在早期可治愈阶段发现这些癌症。”

（译者：orchismessi，编辑 Julie）