Summarize:

Some people have a genetic predisposition for breast cancer. If there is a history of breast cancer in your family, you may be at risk. Look at the history of both sides of your family (mother's and father's), since the genetic predisposition for breast cancer can come from either side. The same genes that are linked to breast cancer are also linked to other kinds of cancer. Make note of any history of ovarian, pancreatic, or high grade prostate cancer in your family. Let your doctor know if there is a history of any of these types of cancer in your family. Mutations to these genes can make you extra susceptible to breast cancer and certain other types of cancer. It is especially important to test for these mutations if there is a history of breast and ovarian cancer in your family. Aside from genetic predisposition, there are other factors that could be related to your personal risk for breast cancer. Talk to your doctor if you have any of the following risk factors: Age: Women over 50 are more likely to develop breast cancer. Dense breasts: Women with breasts that are "dense" or high in connective tissue (as opposed to fatty tissue) have an elevated risk of developing breast cancer. Early menstruation: If you began menstruating at the age of 12 or younger, you may be at slightly higher risk for developing breast cancer. No pregnancy, or pregnancy late in life: If you have never been pregnant, or became pregnant for the first time after the age of 30, you may have a slightly increased risk for breast cancer. A previous history of breast cancer or non-cancerous breast diseases. Some medical procedures and medications can also increase your risk of developing breast cancer. Talk to your physician if you have used any of these medicines or undergone any of these medical procedures: Hormone therapy (e.g. hormone replacement therapy after menopause) or hormonal contraceptives (e.g. birth control pills). Radiation therapy for other cancers of the chest and breasts. The drug diethylstilbestrol (DES), a drug that was sometimes administered to pregnant women between 1940 and 1971.
Look at your family history. Get tested for BRCA1 and BRCA2 genetic mutations. Look at your personal health history. Look at your history of medical treatments and medications.