We began our cancer odyssey with perhaps the most frequently asked question, ‘What causes cancer?’, and the shortest reply: ‘Mutations’. But that’s a biologist’s answer. What we really want to know is ‘How?’ How do these changes come about and, of course, what can we do about them? Broadly speaking, two categories have been long-recognized as the underlying causes of cancer – ‘hereditary’ and ‘environmental’. The former refers to the state of our DNA when we get it – mutations passed to us at birth kick off about 10 per cent of all cancers. The second group includes everything else and in doing so lumps together things that we can’t control (e.g., radiation from the ground) with those we can (e.g., smoking). The latter really should include a sub-group: ‘self-destruction’ perhaps.