How is caffeine related to breast cancer?

For most types of cancer, coffee appears either to decrease risk of cancer, or to have no effect on cancer risk at all. Even in countries with very high intake of caffeine from coffee, such as Scandinavian countries, research does not support a link between coffee or caffeine and breast cancer risk.
Regularly consuming at least two cups of coffee per day might increase the effectiveness of breast cancer treatment, according to recent research.
Coffee has been shown to be an iron reducer (containing compounds that remove iron from the body), which may be helpful in reducing iron for some women (since high stores of iron can contribute to breast cancer risk), but could negatively impact women with marginal stores of iron.
But don’t forget that caffeine can negatively affect people with other health conditions. If you have high blood pressure, a rapid heart rate or other heart-related issues, please talk to your doctor about how much caffeine is safe for you.