I rode a horse without a bra which caused a lot of painful and extreme bouncing around for my breasts. lasted for 30 mins in all with about 30 secs for the most extreme impact. some redness. can i get breast cancer or other diseases from this?

No worries: Here in California, the law requires Cancer Warning signs everywhere, because everything we eat, touch, breathe can cause cancer. That's a reality of life. Everything on Earth can cause cancer, but the true question is, how likely is it to happen? Haven't heard of horse-riding causing cancer, with or without bras. That said, wearing safety equipment is a good idea anyway. No worries!