The average American woman has a one in eight chance of developing breast cancer during her lifetime, according to the American Cancer Society. But this composite risk does not reflect the fact that most women have some characteristics that would increase her risk, such as age, and some factors that can decrease her risk, such as weight loss. While it is difficult to accurately predict any individual's risk of developing breast cancer, our growing understanding of the ways in which breast cancer develops has helped doctors and scientists define categories of risk factors and protective factors for breast cancer. At Houston Methodist, we can help patients evaluate their risk and implement changes to reduce their chances of developing breast cancer.

Talking to your doctor about your risk for breast cancer is an important step to take. At Houston Methodist we can help you, providing information about and ways you may be able to reduce your risk. These conversations are also a great way to discuss breast cancer detection — finding a cancer early is one of the best ways to improve the likelihood of successful treatment.

Even with everything we know about breast cancer, there are still many unknowns. Every person is different, and what's appropriate for one person may not be for another. This applies to risk factors for developing cancer: having one or more risk factors does not necessarily mean you will develop breast cancer, but it does mean you are armed with knowledge that can help you make important decisions regarding your breast health. On the other hand, not having risk factors does not guarantee that you will be free of the disease.

Risk Factors for Breast Cancer
An increased incidence of breast cancer has been found with the following risk factors:

  • Family history of breast cancer
  • Personal history of breast cancer or ovarian cancer
  • Prior personal history of non-cancerous (benign) tumors
  • A mutation in certain genes, such as the BRCA1 (breast cancer 1, early onset) or BRCA2 (breast cancer 2, early onset)
  • First menstrual period before the age of 12
  • First child born after the age of 30 or having no children
  • Menopause began after the age of 55
  • Advancing age — about 80 percent of all cases occur after age 50
  • Lifestyle risk factors:
    • Consuming more than one alcoholic drink each day
    • Being overweight, especially after menopause or if excess body fat is distributed in the upper part of the body
    • Taking birth control pills for 4 or more years before the first full-term pregnancy (may increase risk slightly)
    • Using hormone replacement therapy (to treat menopausal symptoms) for 4 years or more
    • Estrogen (naturally occurring)
    • Exposure to radiation (for example, working around radiation)

The following protective factors may decrease the risk of breast cancer:

  • Exercise
  • Decreased exposure to estrogen
  • Medications to interfere with estrogen binding to tumor cells (for example, Tamoxifen for hormone-receptor positive breast cancer)
  • Medications to inhibit estrogen production (aromatase inhibitors for hormone-receptor positive breast cancer)
  • Prophylactic mastectomy (the removal of both breasts as a protective measure when there is no sign of cancer)
  • Prophylactic oophorectomy (the removal of both ovaries as a protective measure when there is no sign of cancer)


The following have not been proven to be risk factors for breast cancer, or their effects on breast cancer risk are not known:

  • Abortion
  • Oral contraceptives (except as noted above)
  • Environment
  • Diet (except as the diet affects obesity)
  • Active and passive cigarette smoking
  • Use of statins (a class of cholesterol-lowering drugs)


As a leading provider of cancer care, Houston Methodist is changing patients' lives — and the course of medicine worldwide — through our research and clinical trials. If you do need cancer services, many patients like to know that Houston Methodist can offer a full array of care. But what we would most like to do is to help you stay cancer free.

You can read more about our breast cancer services by clicking on the topics below:


You can learn more about Houston Methodist diagnostic and risk-assessment services by clicking on the type of service below:


Houston Methodist provides mammograms and breast care at the following convenient locations: