Cancer occurs when some cells begin to grow abnormally and uncontrollably. Those rapidly accumulating cells form masses, or tumors. In the breasts, tumors usually form in the milk ducts or the lobules, the glands that produce milk. In rare cases, cancer can form in the breast’s connective tissue – muscles, fat, and blood vessels.

What causes those cells to start growing so rapidly and uncontrollably is not entirely known, although researchers at UT Southwestern and elsewhere work every day to find the answer. Some factors are known to increase the risk of cancer.

Risk Factors

Some of the risk factors for breast cancer can be controlled, while others cannot.

Risk factors include:

Risks You Can Control

  • Alcohol use
  • Being overweight
  • Tobacco use

Risks You Cannot Control

  • Age – 95 percent of new cases in women over 40
  • Early menstrual periods – before age 12
  • Family history of breast cancer
  • Gender
  • Hereditary factors – specific inherited genes
  • Late childbirth – first time after age 35
  • Late menopause – after age 55
  • Personal history of breast cancer
  • Postmenopausal hormone therapy
  • Radiation exposure – during medical treatments as a child or young adult

Lower Your Risk

While there’s no definitive way to prevent breast cancer, there are ways to lower your risk:

  • Exercise vigorously at least 30 minutes each day.
  • Maintain a healthy weight.
  • Eat a diet that’s rich in fruits, vegetables, poultry, fish, and low-fat dairy products.
  • Avoid alcohol or limit yourself to no more than one drink a day for women and two for men, according to the American Cancer Society.
  • Avoid or quit smoking.

Hereditary Factors

If hereditary factors put you at a higher risk for breast cancer, you may be able to reduce your risk with medication. One of the largest breast cancer prevention trials showed that the medications tamoxifen and raloxifene can lower the risk of invasive cancer in women.

For non-invasive cancer, raloxifene was less effective at reducing risks, while tamoxifen was associated with the development of uterine cancers and blood clots. Your doctor can decide if one of these drugs is right for you.

Women at high risk because of a genetic mutation also may choose to have their breasts surgically removed as a preventive measure. UT Southwestern specialists can help determine your risk with groundbreaking genetic testing and counseling, and can assist you in understanding all your options.