Why is breast tissue so susceptible to cancer when it isn't exposed to toxins?

[Riemann]

@The_wind_of_my_soul

Daniel E. Lieberman addresses this question in his book The Story of the Human Body . To directly quote his book:

Cancer, for example, is actually an aberrant evolutionary process going on within a body.

From a previous thread

Is cancer primarily a mammalian disease?

Cancer, or at least the dysregulated proliferation of cells in some manner, is the natural fate of all multicellular organisms if they live long enough. Even plants get a form of cancer. The remarkable thing is that multicellular life exists at all. For billions of years, all of life was single-celled organisms, and most of it still is. This is a more natural evolutionary state, since every cell may have descendants. As cells compete for survival, every cell has a potential evolutionary fu…