Estrogen = Breast Cancer?

Factual Questions
1

This thread links to a study where it talks about how “estrogen is known to fuel breast cancer.”

I don’t quite understand how this works.

Estrogen is the hormone that makes females females, right? Causes all those sex characteristics like breasts and ovulation. Right? (I’m not sure if I have all this right, since I’m not too well-educated on how hormones/chemicals work in the human body.)

So how can the hormone that gives us breasts and the ability to reproduce ALSO fuel breast cancer? It seems strange.

Does estrogen also fuel cervical/ovarian cancer? Does testosterone fuel testicular cancer?

Are women who take estrogen therapy for whatever reason at a higher risk for breast cancer?

2

Here is some better info on the subject. Basically, estrogen doesn’t cause breast cancer but some tumors grow when they receive estrogen.