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William Hayward 

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With as many as 120 varieties in existence, discovering how cancer works is not easy. The researchers made great progress in the early 1970s, when they discovered that oncogenes, which are cancer-causing genes, are inactive in normal cells. Anything from cosmic rays to radiation to diet may activate a dormant oncogene, but how remains unknown. If several oncogenes are driven into action, the cell, unable to turn them off, becomes cancerous. The exact mechanisms involved are still mysterious, but the likelihood that many cancers are initiated at the level of genes suggests that we will never prevent all cancers. 'Changes are a normal part of the evolutionary process,' says oncologist William Hayward. Environmental factors can never be totally eliminated; as Hayward points out, 'We can't prepare a medicine against cosmic rays.' The prospects for cure, though still distant, are brighter. 'First, we need to understand how the normal cell controls itself. Second, we have to determine whether there are a limited number of genes in cells which are always responsible for at least part of the trouble. If we can understand how cancer works, we can counteract its action.'
癌症现有种类多达120多种，发现其规律实属不易。研究人员在70年代早期取得了很大进展，他们发现导致癌症的癌基因在正常细胞里是不活跃的。从宇宙射线、辐射到日常饮食，任何东西都可能激活一个处于静止状态下的致癌基因，但如何激活尚不为人知。如果若干癌基因被激活，细胞无力排除也就演变成了癌细胞。 导致癌变的确切机制仍是个谜，但许多癌症始于基因这一可能性表明我们将永远不能预防所有癌症。 “变化是进化过程中的一个正常部分，”肿瘤专家威廉•海沃德说道。环境因素永远无法完全消除，正如海沃德所指出的那样：“我们无法准备出一种抗宇宙射线的药。” 治癌前景尽管遥远，但已越来越明朗。 “首先，我们需要了解正常细胞如何控制自己。其次，我们必须查明细胞中是否有一定数量的基因对至少部分麻烦总是负有责任。如果我们能弄清癌症的活动规律，我们就能采取相应的措施。