All women are at risk of developing breast cancer as they age. Thanks to research studies, other factors have been identified that increase, and sometimes lower, an individual’s risk of getting breast cancer.

It is important that each woman understands her individual risk for developing breast cancer and being screened appropriately based on that risk. Some women may not have any additional risk factors, other than being a female that ages. These women are considered at average risk.

See Breast Self-Awareness section for more details.

Having one or more risk factors for developing breast cancer does not mean breast cancer will develop. Risk factors indicate lifestyle, genetic, or biological influences that may lead to breast cancer. Some risk factors affect the development of breast cancer a great deal, and others only a small amount.

A common myth is that a family history of breast cancer is the greatest factor for developing breast cancer. In reality, only 5-10 percent of breast cancers are diagnosed in a woman with a family history. Having a family history does increase your risk, but it is far from the only factor that does.

Although we’ve learned a lot, we still don’t know what causes breast cancer to develop at a certain time in a certain person. It’s likely a combination of risk factors (some of which are still unknown).

We are also unsure why a certain combination of risk factors might cause breast cancer in one person but not in another.

Find a comprehensive review of breast cancer risk factors.

Factors that INCREASE Risk

These are factors found to be established or probable in the development of breast cancer. Again, having one or more of these factors alone does not mean breast cancer will develop. Having one or more of these factors means you are at increased risk of developing breast cancer and should complete appropriate screening tests determined by your medical provider.

Listed in alphabetical order:

  • Age (older)
  • Age at first childbirth (over age 35)
  • Age at first period (before age 12)
  • Age at menopause (over age 55)
  • Alcohol use (2-3 drinks per day)
  • Ashkenazi Jewish heritage
  • Being female
  • Birth control pills (current or recent use)
  • Blood androgen levels (high)
  • Blood estrogen levels (high) after menopause
  • Body weight (heavier) after menopause
  • Bone density (high)
  • BRCA1 or BRCA2 gene mutation
  • Breast density (high)
  • Family history of breast cancer
  • Height (taller)
  • Hyperplasia
  • IGF-1 hormone levels (high) before menopause
  • Light at night/shift work
  • Menopausal hormone therapy (estrogen plus progestin)
  • Personal history of cancer
  • Prolactin hormone levels (high)
  • Race and ethnicity
  • Radiation exposure from medical imaging
  • Radiation treatment during youth
  • Weight gain

Factors that DECREASE Risk

There is no way to prevent breast cancer, but there are lifestyle changes that we can make to help reduce the likelihood of developing breast cancer.

Listed in alphabetical order:

  • Body weight (heavier) before menopause
  • Breastfeeding
  • Carotenoids (pigments found in fruits and vegetables)
  • Exercise after menopause
  • Fruits and vegetables

Factors that DO NOT Affect Risk

Researchers have looked at several factors and, at this time, found they have no correlation between an individual and the risk of developing breast cancer. The following list includes factors that are not related to breast cancer risk, meaning they neither increase nor decrease risk.

Listed in alphabetical order:

  • Abortion
  • Blood organochlorine levels
  • Bras or underwire bras
  • Breast implants
  • Caffeine
  • Cell phone use
  • Deodorant/antiperspirant use
  • Electromagnetic fields (from utility wires, electric blankets, etc.)
  • Hair dyes and hair relaxers
  • Left-handedness
  • Menopausal hormone therapy- estrogen only (less than 10 years of use)
  • Migraine headaches
  • Trauma to the breast

Possible Risk Factors

Researchers have identified several factors that may increase or decrease an individual’s risk of developing breast cancer, but more study is needed before solid conclusions can be made. These factors are still under study.

Possible Factors for Increasing Risk:

  • Birthweight
  • Blood estrogen levels (high) before menopause
  • IGF-1 hormone levels (high) after menopause
  • Insulin levels (high) after menopause
  • Meat consumption before menopause
  • Smoking

Possible Factors for Decreasing Risk:

  • Exercise before menopause
  • Vitamin D

Possible Factors that DO NOT affect risk:

  • Antidepressants
  • Aspirin
  • Dairy products
  • Diabetes
  • Dietary fat
  • Fertility drugs
  • Insulin levels (high) before menopause
  • Meat consumption after menopause
  • Soy