The Preamble to the IARC Handbooks of Cancer Prevention describes the objectives and scope of the programme, general principles and procedures, and scientific review and evaluations. The IARC Handbooks embody the principles of scientific rigour, impartial evaluation, transparency, and consistency. The Preamble should be consulted when reading an IARC Handbook or a summary of an IARC Handbook's evaluations. Separate Instructions for Authors describe the operational procedures for the preparation and publication of a volume of the IARC Handbooks.