什么是肺癌?

肺癌是在肺内无限增殖的异常细胞,这些异常细胞的生长与增殖是不可控的。这些异常细胞并没有正常肺细胞的功能和长成正常肺组织的能力。随着它们的生长,这些异常细胞可以形成肿瘤,并且干扰正常肺给全身供氧的功能。肺癌已成为发病率和死亡率增长最快,对人群健康和生命威胁最大的恶性肿瘤之一。

肺癌的遗传基础

每个人的细胞都有一种被称为DNA的遗传物质。每当一个细胞分裂成两个时,它的DNA也复制了。此后的细胞实际是之前细胞完全一样的复制品,拥有完全一样的遗传物质这样,我们的身体持续填充自己:老的细胞死去,新的细胞代替它们。

癌症来源于细胞内DNA复制时的的错配或者突变。DNA突变可以是由正常年龄增长引起或者环境因素的影响(如吸烟,吸入石棉,暴露于氡气体下)。

肺癌的发生是由一系列的突变累积而成。在真正成为癌症之前,细胞可以是已经有一些突变,也就是发生了前期病变,但仍然可以行使部分正常细胞的功能。当一个细胞发生了基因突变之后,它在分裂时可以将异常的基因传递给越来越多新的细胞,肺组织逐渐丧失了正常的功能。在肺癌的晚期,一些细胞可以通过循环系统转移到在身体别的地方生长,这一过程被称作转移并且新的病灶被称作转移瘤。

原发性肺癌与继发性肺癌

原发性肺癌从肺部开始,肿瘤细胞是异常的肺细胞。有时,别的地方的肿瘤可以转移到肺,因为肺是继发的病灶,所以这种被称作继发性肺癌。例如,肺内的乳腺癌细胞并不是肺癌细胞,而是转移的乳腺癌,这种情况下治疗方案应当选用乳腺癌的治疗方案而不是肺癌的治疗方案

文章编译自:What Is Lung Cancer?

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