Mercury causes many imbalances. I know that it also effects your hormones and if you get your estrogen levels too high, this will cause breast cancer as estrogen causes cells to proliferate. You need to stay away from things that have an estrogenic effect- beef and chicken that have been injected with hormones, plastics, milk and dairy products.

You might want to get the book by John R. Lee, "What your Dr. May not tell you about breast cancer" to learn more about hormones and cancer.

Good luck