>
> I did a very, very quick Google & found this... glanced through it
> super-quickly - looks like it might be at least partially relevant.
> (excerpt: "Background: Fourfold to sixfold higher prostate cancer rates in
> Japanese-American men in the United States compared with Japanese men in
> Japan have been cited to support a role for environmental risk factors in
> the etiology of the disease.")
>
>formatting link
Just dawned on me - wasn't paying much attention (obviously!): that was Japanese vs. Japanese-American men, not vs. Japanese men who moved to America.
Here's another one, & seems to be the right populations. But this one - again at quick glance, appears to cite diet as a likely culprit.
formatting link
Cathy