I think the cardinal rule of learning to write is learning to read first. I learned to write by learning to read.

I began wondering, can one really write a biography of an illness? But I found myself thinking of cancer as this character that has lived for 4,000 years, and I wanted to know what was its birth, what is its mind, its personality, its psyche?

I had seen cancer at a more cellular level as a researcher. The first time I entered the cancer ward, my first instinct was to withdraw from what was going on - the complexity, the death. It was a very bleak time.

Could your medicine be a cell, not a pill? Could your medicine be an organ that's created outside the body? Could your medicine be an environment?

In the laboratory, we call this the six-degrees-of-separation-from-cancer rule: you can ask any biological question, no matter how seemingly distant-what makes the heart fail, or why worms age, or even how birds learn songs-and you will end up, in fewer than six genetic steps, connecting with a proto-oncogene or tumor suppressor.

In Paris, friend of Bequerel’s, a young physicist-chemist couple named Pierre and Marie Curie, began to scour the natural world for even more powerful chemical sources of X-rays. Pierre and Marie (then Maria Sklodowska, a penniless Polish immigrant living in a garret in Paris) had met at the Sorbonne and been drawn to each other because of a common interest in magnetism.

When you immerse yourself in medicine you realise that hope is not absolute. It's not that simple.