THURSDAY, Feb. 2, 2017 -- Women whose breasts are predominantly made up of more dense, glandular tissue face higher odds for breast cancer, a new study finds. The researchers added that, based on their study of 200,000 women, breast density may be the most important gauge of breast cancer risk, eclipsing family history of the disease and other risk factors. "The most significant finding in this study is the impact of breast density on development of breast cancer in the population," said study senior author Dr. Karla Kerlikowske.