Is there any study linking the use of bra with breast cancer? Does bra reduce blood flow to the breasts?

There are several persistent internet rumours about potential causes of breast cancer. One is that wearing a bra, or wearing an underwire bra, causes the disease. The idea that bras may cause cancer was fuelled by the 1995 book called Dressed to Kill by Sydney Ross Singer and Soma Grismaijer. It claims that women who wear underwire bras for 12 hours a day have a much higher risk of developing breast cancer than women who do not wear bras. It also suggests that bras restrict the lymph system, which results in a build-up of toxins in the breasts. However, according to the American Cancer Society, there is no evidence that compression of the lymph nodes by bras cause breast cancer; in reality, body fluids travel up and into the underarm lymph nodes, not towards the underwire. Similarly, there is no sufficient evidence that any types of bras cause breast cancer.