Cocoa / Soy. An inconvenient truth.
No one knows the answer to your question, but it does raise sone interesting questions on diet:
The resource page on this site says over 30% of men have microscopic PC by age 50. Stanford research indicates presence of invasive cancer in 40% of autopsied men over 50. Obviously this never presents a problem for most men.
Japanese men also have PC cells, but it's even less likely for them to develop clinical problems.
The traditional Japanese diet includes a lot of soy, which usually had soy beans and peas (those green things) and fermented products.
This is vastly different to the "soy milk" containing sugar etc available in western supermarkets.
Their consumption of KJ's is very small compared to the typical western diet.
Cholocate: there is a big diffence between eating dark chocolate and drinking some of the cocoa drinks sold in western supermarkets.
Some food for thought