An Iatrogenic Confounding Variable

Extract

Why do some men develop clinically significant prostate cancer whereas others do not? Epidemiologists have pondered this dilemma for decades. During this time, we have learned that many men harbor incidental prostate cancers, some even as young as 30 years, but that most men will not develop clinically significant disease ( 1 , 2 ). Careful examination of racial patterns of disease progression has taught us that environmental factors play a major role in the development of clinically significant disease. Prostate cancers, for example, are relatively rare among Asians living in China and Japan but are more common among Asians who have migrated to western countries or adopted western habits ( 3 ). Diet has frequently been cited as a major potential factor contributing to prostate cancer disease progression, but other environmental factors are receiving increasing scrutiny.

The role of inflammation in the development of prostate cancer has been a target of research for many years ( 4 ). Several intriguing correlations have been identified. In this issue of the Journal, Stark et al. ( 5 ) reported the role of Trichomonas vaginalis infection as a possible environmental factor that facilitates the development of clinically significant disease. Although the researchers were unable to demonstrate a statistically significant correlation between a T. vaginalis seropositive state and overall prostate cancer risk, their findings deserve serious attention.