Some of the daily medication my SIL takes may have played a role. It can cause problems and lead to TIA's or strokes.
My SIL had breast cancer at 31. Forget the correct definition of type but it was the most deadly form to women her age. Developing this type in much older women, progress is very, very slow.
The DR at the time said he was almost going to kill her to cure her. The last two chemo treatments were down in hospital and closely monitored as it almost did.
She is now 63 and has been cancer free since . But the tremendous strength of the chemo has led to other issues and from time to time causes problems.