Risk factors
The exact causes of breast cancer are unknown. Research has shown that the following conditions increase a woman's chances of developing breast cancer:
Personal History: Women who have had breast cancer face an increased risk of developing breast cancer again.
Family History: The risk for developing breast cancer increases if immediate family members (mother, sister or daughter) have had breast cancer, especially at a young age.
Certain Breast Changes: A diagnosis of atypical hyperplasia or lobular carcinoma in situ (LCIS) may increase a woman's risk for getting breast cancer.
Genetic Alterations: Changes in certain genes increase a woman's risk of developing breast cancer.
Estrogen: There is evidence suggesting that the longer a woman is exposed to estrogen (estrogen made by the body, taken as a drug or delivered by a patch) the more likely she is to develop breast cancer.
Late Childbearing: Women who have their first child later (after about age 30) have a greater risk of developing breast cancer than women who have their children at a younger age.
Breast Density: Breasts that have a more lobular and ductal tissue appear dense on mammograms. Breast cancer develops more in lobular or ductal tissue (not fatty tissue).
Radiation Therapy: Women whose breasts have been exposed to radiation during radiation therapy before age 30.
Alcohol: Some studies suggest a slightly higher risk of breast cancer among women who consume alcohol.
