Does "clock" matter in prostate cancer?

The ancient adaptation of a 24-hour circadian clock has profound effect on our daily biochemical, physiologic, and behavioral processes, including the monitoring of sex hormone levels. Although the disruption of the circadian cycle has been implicated in the etiology of hormone-related female breast cancer, few studies have been undertaken to determine if a link exists in the development of the most common cancer type among men whose etiology remains largely unknown: hormone-related prostate cancer. Here, we hypothesize that both altered-lighted environments and genetic variations in genes responsible for maintaining circadian rhythms may result in deregulation of clock-associated biological processes, such as androgen expression, and consequently influence an individual's risk of prostate cancer. There is also a potential for the interaction of genetic variants and exposures, such as evening shift work. Confirmation of this hypothesis will add to our understanding of the role of the circadian clock in prostate tumorigenesis and further facilitate the development of novel risk and prognostic biomarkers for prostate cancer. (Cancer Epidemiol Biomarkers Prev 2006;15(1):3-5).