BRCA1 Gene - Breast cancer and non-breast cells

[dharavsolanki]

Hello.

I came across BRCA1 in my intro to cancer biology class. The BRCA1 gene was discussed and it was mentioned that it is causative (?) for breast cancer. However, it is a tumor suppressor of sorts and is present in all the cells. Then what happens when it comes to other cells? Why does a defect in this particular gene does not cause cancer anywhere else?

Is it because gene expression is silenced? Is it because that the pathways associated with the expressed proteins are disrupted only in the case of breast cells?