Two thirds of cancers are unavoidable even if you live a healthy life, a study has shown.

    Scientists in the United States found cancers are caused by random mistakes in the genetic code that occur when cells divide.

    Lead scientist Cristian Tomasetti, from Johns Hopkins Kimmel Cancer Center in the United States, said, "It is well-known that we must avoid environmental factors such as smoking to decrease our risk of getting cancer.

    "But it is not as well-known that each time a normal cell divides and copies its DNA to produce two new cells, it makes multiple mistakes.

    "These copying mistakes are a potent source of cancer mutations that historically have been scientifically undervalued, and this new work provides the first estimate of the fraction of mutations caused by these mistakes."

    The research, published in the journal Science, indicates that almost two-thirds of cancer-causing mutations are due to DNA copying errors.

    The discovery helps explain why cancer often strikes people who follow all the rules of healthy living and have no family history of the disease.

    Cancers triggered by copying errors could occur "no matter how perfect the environment," according to co-author Bert Vogelstein, also from the Johns Hopkins Kimmel Cancer Center.

    He said, "We need to continue to encourage people to avoid environmental agents and lifestyles that increase their risk of developing cancer mutations. However, many people will still develop cancers due to these random DNA copying errors, and better methods to detect all cancers earlier, while they are still curable, are urgently needed."

    The team studied mutations that drive abnormal cell growth in 32 different types of cancer. The results showed that it generally took two or more critical gene mutations to trigger cancer.

    Overall, 66 percent of cancer mutations resulted from copying errors, 29 percent from lifestyle or environmental factors, and just 5 percent from inherited faulty genes.

    Words to Learn 相关词汇  

    偶然的

    ǒurán de

    random

    proceeding, made, or occurring without definite aim, reason, or pattern

    变异

    biànyì

    mutation

    a relatively permanent change in hereditary material that involves either a change in chromosome structure or number

    得不得癌症 基本看运气

    研究表明，即使生活方式健康，依然有三分之二的癌症是难以避免的。

    美国科学家发现，细胞分裂时产生的基因序列随机错误能致癌。

    美国约翰霍普金斯大学金墨尔癌症中心首席科学家克里斯蒂安?托马塞蒂博士指出：“众所周知，我们必须避开吸烟等环境因素从而减少罹癌的可能。”

    “但是，很多人不知道的是，每当一个正常的细胞分裂并复制DNA从而产生两个新细胞时，会发生各种各样的错误。”

    “这些细胞分裂时产生的错误是导致癌基因变异的重要原因，但是，一直以来，这种观点在科学领域都未受到足够重视。这是第一次有研究猜测认为，癌基因的变异可能源于细胞分裂时产生的错误。”

    这项发表在《科学》期刊上的研究表明，将近三分之二的致癌基因突变可能源于DNA复制时产生的错误。

    这一发现有助于解释为何那些生活方式健康且无家族病史的人会罹癌。

    同样来自美国约翰霍普金斯大学金墨尔癌症中心的伯特?沃格斯坦是本次研究论文的共同作者，他表示，“不管外部环境多么无可挑剔”，由基因复制错误导致的癌症都有可能发生。

    他说：“我们要继续鼓励人们避开那些增加癌基因变异风险的环境因素和生活方式。不过，很多人仍会因为DNA复制时随机产生的错误患上癌症，因此，我们现在急需找到更好的方法及早检测出所有癌症，在可以治愈时发现它们。”

    研究人员对32种癌症中导致细胞异常生长的变异原因进行了研究。研究结果表明，一般情况下，癌症的发生至少需要两种关键基因的变异。

    整体而言，在引起细胞癌变的众多原因中，细胞分裂时产生的错误占比66%，生活或环境因素占比29%，异常基因遗传占比仅为5%。