The Monographs Programme of the International Agency for Research on Cancer. A brief history of its Preamble

Since the early 1970s, the Monographs published by the International Agency for Research on Cancer (IARC) apply rigorous procedures for the scientific review and evaluation of carcinogenic hazards. The Preamble to the IARC Monographs describes the objective and scope of the Monographs Programme, the scientific principles and procedures used in developing a Monograph, the types of evidence considered, and the scientific criteria that guide the evaluations. This article presents an overview of the historical development of the Preamble from the time it began to take shape in the late 1970s up to and including the most recent update in 2019. Over the years, the IARC Monographs Programme has taken account of scientific and procedural advances in identifying, reviewing, evaluating, and integrating evidence to define causes of human cancer. Since the previous edition of the Preamble in 2006, the new developments include a stronger emphasis on mechanistic evidence based on key characteristics of carcinogens; greater consideration of exposure assessment methods in epidemiological studies; and integration of the streams of evidence on cancer in humans, cancer in experimental animals, and mechanisms in reaching the overall evaluations. Thus, the Preamble now allows an evaluation process in the absence of data from animal studies, and the evidence on key characteristics of cancer may be contributed by new approach methodologies, thus potentially reducing or avoiding the use of experimental animals.