There is no shonage of books on cancer. Why publish another? Simply because the subject is important: possibly the most important challenge facing medicine today, and consequently the focus of one of the faslest-growing areas of fundamental biological research. The quest to understand and control cancer is so absorbing that from time 10 time we really need to pause for a moment and try to take sk of the situation. Given the sheer breadth of cancer-related research that is not an easy task. This book, together with its planned successors in the series Cancer Biology and Medicine. represents our attempt to draw back from the bench or the bedside for a moment and take a slightly longer look at what we are doing, what we are trying to do, and where we stand. It is impossible to be comprehensive or even representative of more than a fraction of relevant knowledge. but that is no excuse for not trying to see things in perspective. Accordingly we set out to persuade a number of our colleagues to join us in writing a book which might admit a little fresh air into the confined atmosphere within which we mostly work: a glimpse, perhaps. of fresh vistas.