I hade never heard of it either but googled after you post, it seems there is less than 1% of breast disease that this is the cause
It can be found with self regular checks same as feeling for lumps related to cancer, though sometimes fibres cannot be felt.
I presume you have felt lumps or pain in breast area, the other thing this can affect men as well so hopefully after your post type 1 people will check themselves and not ignore pains or lumps
It was found about 30 years ago so relatively new, and your GP may not have known about it, due to low instances