Precancerous states provide valuable information about the natural history of some forms of malignant disease in man, and have important therapeutic implications in the identification of particular high-risk groups of patients and the introduction of screening procedures and early prophylaxis. However, precancerous states are still poorly characterized, and one of the main aims of this book is to review the common precancerous lesions in a critical manner and to consider some of the newer techniques that may help to identify them more accurately in the future. The subject matter is presented on a conventional systematic basis, together with general chapters on genetic aspects and epidemiology and a final section dealing with broad principles of clinical management. Experimental studies are included whenever they contribute to the argument.