Location, location, location
We know that there are places in the world with higher incidences of breast cancer. What we don't understand yet is the reason for it.
In the region in which the founders of this site live there is a know increase of breast cancer diagnosis. There are many theories as to why, the most common is that the water drinking supply might have been compromised by old factories and that toxins leached into the well water of residents.
This of course is not something that we can prove without extensive research.
Consider there to be a lot of truth behind the Erin Brockovich story, the dramatization of which portrayed by Julia Roberts learning about cancers caused by toxins leaching into the environment in a small town in California and then becoming a powerful environmental activist.
There is also some research being done about altitude playing a role in the incidence of certain cancers.