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.

I wanted to explore cancer not just biologically, but metaphorically. The idea that tuberculosis in the 19th century possessed the same kind of frightening and decaying quality was very interesting to me, and it seemed that one could explore the idea that every age defined its own illness.

Down to their innate molecular core, cancer cells are hyperactive, survival-endowed, scrappy, fecund, inventive copies of ourselves.

I think when we use 'stress', we are often using a kind of dummy word to try to fit many different things into one big category.

There's a phrase in Shakespeare: he refers to it as the 'hidden imposthume', and this idea of a hidden swelling is seminal to cancer. But even in more contemporary writing it's called 'the big C'.

All cancers are alike but they are alike in a unique way.

I left Delhi in 1989 and remember very little of how life used to be then. Increasingly, in my recent visits to Delhi, I've started to realize that the city has become intellectually very lively. It makes me want to discover the city over and over again.