A、Some tissues are more vulnerable to cancer. B、Most types of cancers have caused by unhealthy lifestyle. C、Some of the cancers

Most types of cancer can be put down to bad luck rather than risk factors such as smoking, a study has suggested. A U. S. team were trying to explain why some tissues were millions of times more vulnerable to cancer than others. (16) The results, in the journal Science, showed two thirds of the cancer types analyzed were caused just by DNA changes rather than lifestyle.
    However, some of the most common and deadly cancers are still heavily influenced by lifestyle. (17-1) Cancer Research U. K. said a healthy lifestyle would still heavily increase the odds in a person’s favor. So is it time to light-up, drink and eat what you want without a care in the world? It won’t come as a surprise that the answer is no. All cancers have an element of chance—a chance that decides whether your DNA acquires a change that leads to cancer. The study shows that two thirds of cancer types are simply accidental. (17-2) But the remaining one third are still heavily influenced by the choices we make. Too much alcohol, long time in the sun or being overweight mean we are playing with loaded chance and the odds are not in our favor. Remember smoking accounts for a fifth of all cancers worldwide.
    These findings are a reminder that cancer is often just bad luck and the only option is early detection. (18) Cristian Tomasetti, an assistant professor and one of the researchers, said a focus on prevention would not prevent certain cancers. "We should focus more resources on finding ways to detect such cancers at early, curable stages.
16. What does the U. S. team find?
17. Why did Cancer Research U. K. still suggest people have healthy lifestyle?
18. What does Cristian Tomasetti mean?