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

研究顯示，大多數類型的癌癥可以歸結為運氣不好，而非吸煙等風險因素所致。

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

美國的一個研究團隊試圖對人體內部分細胞組織的癌變傾向相比同類大上數百萬倍的現象作出解釋。

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

研究結果表明三分之二的癌癥種類是由潛在的突變風險引起，而非生活方式。這一結果刊登在《科學》雜志上。

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

不過一些常見的癌癥和致死率極高的癌癥在很大程度上依然受生活方式的影響。

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

英國癌癥研究（Cancer Research UK）表示健康的生活方式依然能夠幫助我們降低患癌的風險。

Time to throw caution to the wind?

我們可以盡情享樂了嗎？

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

這是否意味著我們可以放下顧慮盡情享樂呢？

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

不用說答案當然是否定的。

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

所有癌癥都有命中的可能——就像投骰子一樣，它能決定你的DNA是否會出現導致癌癥的突變。

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

美國的研究團隊發現三分之二的癌癥僅僅是湊巧發生的。

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

而剩下的三分之一依然取決于我們自己的選擇。

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、暴曬、超重很可能會使我們投出的骰子停在患癌的一面，避免癌癥的勝算將不在我們這邊。

Remember smoking accounts for a fifth of all cancers worldwide.

我們不能忘記全球五分之一的癌癥是由吸煙引起的。

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

這些研究結果提醒我們，厄運導致患癌，唯一的補救措施是盡早發現。

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

但是這并不能成為放棄新年計劃的借口。

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.

在美國，患肺癌的人數占全國人口的6.9%，腦癌人數占0.6%，0.00072%的人曾患有喉軟骨腫瘤。

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

香煙產生的毒素能夠解釋為什么肺癌相比其他癌癥更為常見。

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.

盡管消化系統比之大腦更易受到周圍毒素的影響，但患上腦瘤的風險卻是患上小腸癌的三倍。

Root of cancer

癌癥的根源

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

這個來自約翰霍普金斯大學彭博公共衛生醫藥學院的研究團隊認為答案在于細胞組織的再生。

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

人體通過不斷分裂干細胞替代衰老的細胞。

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著突變風險，它會使干細胞更傾向于癌變。

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

人體內各個細胞組織的分裂速度不一。腸道內的細胞更新較快，大腦內的細胞分裂速度較慢。

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.

研究者們將人體內31個組織干細胞一生分裂的次數和其癌變的風險作了比較。

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.

他們得出結論，三分之二的癌癥類型歸結于運氣太差，干細胞在分裂過程中遇到了無可避免的突變情況。

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

惡性膠質瘤（腦癌）、小腸癌以及胰腺癌被包括在內。

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

作為研究團隊一員的腫瘤學助理教授克里斯蒂安·托馬賽蒂（Cristian Tomasetti）說，這些癌癥無法通過預防手段來避免。

"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.

“如果細胞組織中如果三分之二的癌變現象可以用干細胞分裂時的DNA突變來解釋的話，那么生活方式和行為習慣的改變確實會大大降低患上某種癌癥的風險。但這些改變無助于避免其他癌癥類型。”

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

“我們應該投入更多資源，以便在早期可治愈階段發現這些癌癥。”

（譯者：orchismessi，編輯 Julie）