Because we haven't been asking these questions and we haven't been tracking these, I can't give you a number. However, I do know a number—those are just the people I've spoken with, but I'm one person—who have had this surgery so that they can do their job.
We don't ask about breast injuries in basic training. We don't ask about breast injuries when we go to our medic. In sport we do or we have started to. The bruising and the ischemia, or the lack of blood flow to the area that actually causes tissue death, are way more common than you would think. Maybe if you put on one of these vests you would understand.
I can't give you numbers, but it's alarmingly common among the people I support. Again, I'm just one person. I've only lived in Ontario and New Brunswick. I've only supported the bases there.