Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. Talk with your doctor if you think you may be at risk.
Older age is the main risk factor for most cancers. The chance of getting cancer increases as you get older. Other risk factors for breast cancer include:
- A family history of breast cancer in a first-degree relative (mother, daughter, or sister).
- Inherited changes in the BRCA1 and BRCA2 genes or in other genes that increase the risk of breast cancer.
- Drinking alcoholic beverages.
- Breast tissue that is dense on a mammogram.
- Exposure of breast tissue to estrogen made by the body:
- Menstruating at an early age.
- Older age at first birth or never having given birth.
- Starting menopause at a later age.
- Taking hormones such as estrogen combined with progestin for symptoms of menopause.
- A personal history of invasive breast cancer, ductal carcinoma in situ (DCIS), or lobular carcinoma in situ (LCIS).
- A personal history of benign (noncancer) breast disease.
- Being white.
- Treatment with radiation therapy to the breast/chest.
Source and full text: National Cancer Institute http://www.cancer.gov/types/breast/patient/breast-treatment-pdq#section/_125