 Hormone therapy

Treating menopausal symptoms with the hormone combination of estrogen and progesterone for four or more years increases your risk of breast cancer. In addition, therapy with estrogen and progesterone can make malignant tumors harder to detect on mammograms, leading to cancers that are diagnosed at more advanced stages and that are harder to treat. Using estrogen alone hasn't been shown to increase breast cancer risk in postmenopausal women.