A risk factor is something that increases your likelihood of getting a disease or condition.

It is possible to develop breast cancer with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing breast cancer. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

Gender

Breast cancer is found predominantly in women and is the most common form of cancer in American women. However, men can develop breast cancer, as well.

Although there is great emphasis on risk factors for developing breast cancer, a great many cases occur in patients with no known risk factors.

Genetic Factors

Women who have a family history of breast cancer (mother, sister, or daughter) have a higher risk factor of developing breast cancer. However, a lack of family history does not protect you from developing breast cancer; approximately 90%-95% of women who develop breast cancer have no family history of this disease.

Additionally, having a mutation in the BRCA1 or BRCA2 breast cancer genes increases your risk.

Age

The chance of developing breast cancer increases with age; three out of four cases occur in women over age 50. However, it is never safe to say that “you are too young to get breast cancer.”

Medical Condition

The following medical conditions have been found to increase the risk of developing breast cancer:

• Prior personal history of breast cancer, or other abnormalities in the breast tissue
• Breasts that have a high proportion of lobular and ductal tissue instead of fatty tissue (that is, dense breasts)
• Previous breast exposure to radiation therapy before age 30
• Pregnancy after age 30, or no pregnancy at all
• Overweight, particularly after menopause
• Increased exposure to estrogen, which includes:
  • First menstrual period before age 13
  • Menopause after age 51
  • Prolonged use of estrogen replacement therapy
• Previous biopsy results that indicate atypical hyperplasia or radial scar formation

Specific Lifestyle Factors

Lifestyle factors that increase breast cancer risk include:

• Drinking three or more alcoholic drinks daily
• Having a sedentary lifestyle
• Smoking

Ethnic Background

In the US, Caucasian, Hawaiian, and African-American women have the highest rates of breast cancer. The lowest rates occur among Korean, American Indian, and Vietnamese women.