Carolinas HealthCare System

Causes, Incidence, and Risk Factors

The cause of breast cancer is not known. One in 8 women will be diagnosed with breast cancer.

Risk factors you cannot change:

  • Age and gender: Your risk of developing breast cancer increases as you get older. Men are 100 times less likely than women to get breast cancer.
  • Family history of breast cancer: You may have a higher risk of developing breast cancer if you have a close relative with breast, ovarian, uterine, or colon cancer.
  • Genes: About 10 percent of women with breast cancer have an abnormal gene that makes them more likely to develop the disease.
  • Menstrual cycle: Starting your period before age 12 and going through menopause after age 55 increases your risk of developing breast cancer.

Risk factors you can change to decrease your risk of developing breast cancer:

  • Alcohol use: Drinking more than two glasses of alcohol a day increases your risk of breast cancer.
  • Childbirth: Women who have never had children, or do not have children until after age 30, are at increased risk of breast cancer. Breastfeeding may also reduce your risk of getting breast cancer.
  • DES: If you took the medication diethylstilbesterol (DES) you may have an increased risk of developing breast cancer.
  • Hormone replacement therapy (HRT): If you took hormone replacement therapy with estrogen for many years you have a higher than normal risk of developing breast cancer.
  • Overweight: Being overweight is associated with a higher risk for breast cancer, particularly in postmenopausal women. Exercise and healthy eating will contribute to meeting this goal.
  • Smoking: American Cancer Society researchers have found an increased risk of breast cancer in women who smoke. Ask about our smoking cessation program.

Other risk factors:

  • Radiation: If you received radiation treatments to the chest as a child or young adult, you have an increased risk of developing breast cancer.

Warning Signs

There are several warnings signs for breast cancer. If you have one of these signs you should report it to your health care provider.

  • A mass, lump, firmness, thickening , or pain in or near the breast, or in the underarm area that is still there one week after your menstrual period.
  • A clear or bloody nipple discharge.
  • A change in the look or feel of the skin on the breast or nipple (red, scaly, dimpled, inverted, or puckered).
  • These changes may be found when performing monthly breast awareness exams, by your practitioner doing a breast exam, or by your partner. Being familiar with how your breasts feel is important so you will recognize any change.
  • Breast exams should be performed at the same time each month, three to five days after finishing your menstrual cycle. After menopause you should perform the exam on the same day of each month.