Are You Dressed to Kill
They found that wearing a bra more than 12 hours a day dramatically increased the incidence of breast cancer, cystic breasts (also known as tight-bra syndrome), breast pain, breast tenderness and other breast issues. Women who wear bras 18-24 hours/day have over 100 times greater incidence of breast cancer than those who go bra-less. So, basically you are 3-4 times more likely to get breast cancer from wearing a bra, than by smoking cigarettes!