Presentation of Study Results: The Authors’ Responsibility

Environmental Health Perspectives • volume 120 | number 9 | September 2012 A 343 due to disease misclassification, we (Camargo et al. 2011) concluded that our meta-analysis supports the IARC classification. This illustrates again that meta-analyses are not free from subjective decisions and interpretations. In conclusion, meta-analyses are a quantitative statistical tool that, in some instances may inform causal inference, but they never alleviate the need for critical review of all available data; narrative reviews by an interdisciplinary IARC Working Group may be, in some cases, more informative than a synthetic meta-analysis. Therefore, although a comprehensive review of all original data is required, a comprehensive review of all meta-analysis may not be warranted, particularly when the meta-analyses are outdated or cover only a subset of the original studies. The current “Preamble to the IARC Monographs” (IARC 2006) provides the Working Group with all options to perform quantitative meta-analysis where appropriate and helpful for causal inference. Different approaches have been applied in the history of the IARC Monographs. The Volume 100 series of the IARC Monographs confirmed all Group 1 carcinogens identified during the 40-year history of the monographs, which in turn confirmed that the procedures of the IARC Monographs are robust. With more epidemiological studies becoming available for each agent, additional cancer sites being investigated, and relatively small effect estimates becoming center of the discussion, the need for meta-analyses is likely to increase. The authors declare they have no actual or potential competing financial interests.