Amanda Black

PhD, MPH

NCI, DCEG, EBP

Staff Scientist

PLCO (Learn more about this study)

PLCO-33

May 21, 2013

Soy Consumption and Risk of Prostate Cancer Risk in Men

The US has one of the highest incidence rates of prostate cancer whereas Asian countries have substantially lower rates of disease. However, the incidence rate in Asian men living in the US is significantly higher than those living in Asian countries. This suggests a key role of environmental influences, such as dietary practices, in the development of prostate cancer. Soy has long been a major source of dietary protein for Asians. It is a unique dietary source of compounds called isoflavones that act like the hormone estrogen in humans and have been found to inhibit tumor cell growth. Evidence from epidemiologic studies also suggest that soy consumption may protect against prostate cancer. However, the majority of studies to date have been of case-control design and include only men of Asian descent. Further, only one of the existing cohort studies has shown a reduced risk of prostate cancer in men who consume soy, the others are null. Recent findings from an animal study suggest that a combination of soy and tomato further reduces the risk of prostate cancer than soy alone but this has not been addressed in a cohort setting. Therefore, we propose to investigate the association between soy consumption and prostate cancer risk and the combination of soy and tomato consumption in prostate cancer risk.