Well, I did it.  I did a Google search, and I got an email address for Dr.
Tina Clarke, who has been studying this situation.  I wrote her:

>I recently heard about the high incidence of breast cancer in Marin
>County; I saw the article at ABCNews.com.  It mentioned a number of
>different factors that are being considered as the cause, but there was
>nothing about any examination of the foods these women are eating. ...
>(snip) ... I bet there are a lot of vegetarian women in Marin
>County!  Have you, or anyone, looked into this possibility?

And a couple of hours later, she replied:

>Thanks for your thoughtful ideas.  I am not familiar with the relation of
>vegetarianism to diet... (snip) I am referring your idea via cc above to
>Marin Breast Cancer Watch, an excellent grassroots organization that is
>aggregating ideas for future studies and coordinating future research in
>the county.

So, perhaps we've started something ... I must say, I'm a bit surprised to
find that they hadn't considered diet as a risk factor up to now :^?