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Most Common Risk Factors of Breast Cancer

Breast cancer can develop for a variety of reasons. Some of these factors are in our control (lifestyle and habits), while others are not (genetics). Following are some common risk factors for women. If you are concerned about your specific risk for breast cancer, contact your doctor to discuss the best course of action to help reduce your risk of breast cancer.)

  • Family history: Your risk may increase if an immediate family member has been diagnosed with breast cancer, particularly mothers, sisters and daughters.
  • Age: Most breast cancers are diagnosed in women older than age 50.
  • Race: While the risk is higher for white women, African-American women have a higher risk of not surviving the disease..
  • Menstruation and menopause: Beginning menstruation before age 12 or entering menopause after age 55 means prolonged lifetime exposure to estrogen and progesterone, which may increase your risk.
  • Hormone therapy: Risk increases when the combination of estrogen and progesterone has been used for four or more years. This treatment for menopausal symptoms may also make malignant tumors harder to detect on mammograms.
  • Not having children or pregnancy after age 30: Estrogen levels are lower during pregnancy, which may protect breast tissue from estrogen exposure. However, if your first full-term pregnancy comes later in life after age 30, your prolonged, uninterrupted exposure to estrogen could increase your lifetime risk of breast cancer.
  • Exposure to radiation: Risk increases if you received radiation treatments to your chest as a child or young adult, but the risk is greatest if treatments occurred as an adolescent during breast development.
  • Genetics: Mutations in one of several genes, namely BRCA1 and BRCA2 genes, can increase your risk. These genes normally help prevent cancer by making proteins that keep cells from growing abnormally. Since genetic mutations can be inherited, Memorial Hermann offers genetic counseling and testing for women who elect to get tested to determine if they also carry the mutation.
  • Personal history: Having breast cancer in one breast significantly increases your risk of developing it in the other breast.
  • Alcohol consumption: Your risk increases with the amount of alcohol consumed, starting with two alcoholic drinks daily.
  • Excess weight: Your risk increases if you gain weight during adolescence, after menopause or if you have more body fat around and above the waist.
  • Dense breast tissue: Breasts are considered “dense” if they have an overabundance of fibrous or glandular tissue and minimal amounts of fat. Approximately 43 percent of women between the ages of 40 to 74 years old are classified as having dense breasts.

Types of Breast Cancer

Most breast cancers are localized to the mammary gland, either in the ducts that carry milk to the nipple (ductal carcinoma) or in the milk-producing glands themselves (lobular carcinoma).

If a screening exam shows (a suspicious pattern of cell growth, a biopsy will be performed, and if there is a diagnosis of cancer, the exact type of breast cancer will be identified. Further testing will then be conducted to help your determine if the cancer has spread into surrounding tissues. Cancer that has not spread is called an in situ breast cancer, while cancer that has spread, it is called an invasive breast cancer.

In addition to ductal and lobular carcinomas, the following types of breast cancer exist:

  • Estrogen Receptor (ER)-Positive Breast Cancer: Many breast cancers have estrogen receptors on the surface of their cells and as a result are sensitive to the hormone estrogen. They are called estrogen receptor-positive cancer or ER-positive cancer.
  • Progesterone Receptor (PR)-Positive Breast Cancer: Other breast cancer cells have progesterone receptors on the surface of the cell, making them sensitive to progesterone. These tumors are called PR-positive cancers.
  • HER2-Positive Breast Cancer: Some women have HER2-positive breast cancer. HER2 is a gene that helps cells grow, divide and repair themselves. When cancer cells have too many copies of this gene, they grow faster. Tumor cells can be any combination of ER/PR and HER2 positive or ER/PR and HER2 negative, with an excess of receptors on the cell’s surface.
  • Inflammatory Breast Cancer: This is a less common type of invasive breast cancer that accounts for about 1 percent to 5 percent of all breast cancers. Typically, the skin of the breast appears red and swollen, and can be confused with symptoms of infection or cellulitis.

If you are at an increased risk for breast cancer or want to discuss your breast cancer risk, schedule an appointment with a health care provider.