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Invited commentary: screening and the elusive etiology of prostate cancer.

The role of lifestyle risk factors in prostate cancer risk remains elusive despite a large number of epidemiologic studies. In a pooled analysis of data from South and East Asian countries published in this issue, Fowke et al. (Am J Epidemiol. 2015;182(5):381-389) found no evidence for an association between prostate cancer mortality and obesity, alcohol, or smoking. Prostate cancer screening is very uncommon in these countries, and previous evidence for associations with lifestyle factors comes primarily from studies carried out in North America, where screening is very common. Fowke et al. concluded that screening biases are likely to explain the differences in study results. In this commentary, we discuss the potential influence of population-based cancer screening programs in estimates of association from epidemiologic studies. This highlights the importance of carefully considering the impact of screening in the analysis and interpretation of results, in order to advance our understanding of the etiology of cancers that can be detected by screening.