Awareness of epidemiology's limitations could reduce impact of false-positive canc...( False-positive results are an inhere...),Health

False-positive results are an inherent risk in cancer research, particularly in observational epidemiology studies. The frequency and impact of misleading results can be mitigated if researchers use more exacting standards when interpreting and reporting results, according to a commentary in the July 8 online issue of the Journal of the National Cancer Institute. Additionally, the impact of false-positive results could be lessened if the researchers and other stakeholders, including journal editors, the media, and consumers, evaluated the results with a more critical eye.

In the commentary, Paolo Boffetta, M.D., of the International Agency for Research on Cancer in Lyon, France, and other senior researchers from Vanderbilt University in Nashville, Tenn., and the Mario Negri Institute in Milan, Italy, discuss some of the key pitfalls of epidemiological research. For example, the authors describe what has happened over the last decade and a half after one small study reported an apparently strong association between pesticide residues in women's blood and the risk of breast cancer. Since then, seven more studies have examined the association, and successive meta-analyses that incorporated the accumulating data showed a decreasing relative risk from a more than four-fold increased risk to no increased risk. That pattern of decreasing summary risk indicates that the initial observation was incorrect.

Common problems that can lead to the occurrence and reporting of false positives include chance, systematic errors in the design or analysis of a study that introduce various types of biases, inadequate accounting for confounding variables, multiple subgroup analyses, and a preference amongst authors and editors to report positive, novel, or statistically significant results rather than results that suggest no association. Although researchers and readers may think these factors have a relatively small impact on the outcome of a study, the auth
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