Breast Cancer Aging

Many risk factors and causes contribute to breast cancer, and women become at higher risk for developing breast cancer as they age. According to the Breast Institute (2010), women between age 75 and age 79 have the highest rate of breast cancer development, at 464 cases per 100,000 women. Women over 40 account for 95 percent of new breast cancer cases and 97 percent of deaths from the disease. This is why doctors recommend regular mammograms for older women, particularly those who are post-menopausal.

Age-Related Risk Factors

Certain breast cancer risk factors increase with age. These include:

  • Estrogen exposure: Research has determined that estrogen exposure promotes the development of breast cancer. Women who have been exposed to estrogen for a greater portion of their lives are thus at higher risk. Specifically, women who first menstruated before they were 12 years old, entered menopause after 55, used hormone replacement therapy (HRT) during menopause or had their first child after age 35 have significantly higher breast cancer risk because of greater estrogen exposure (National Cancer Institute, 2008).
  • Lifestyle: Smoking cigarettes, abusing alcohol and leading a sedentary lifestyle damages cells and increases the risk of cancer, including cancer of the breast. The longer one smokes, drinks or stays inactive, the greater the risk of developing cancer. Thus, older women who have lived their entire lives as inactive smokers and drinkers have greatly increased their risk of developing breast cancer.

Aging Breast Tissue and Breast Cancer Risk

As a woman ages, her milk-producing glands, or “lobules,” begin to shut down. The natural process is known as “lobular regression” or “involution.” Many medical professionals believe that breast cancer originates in the lobules. A large Mayo Clinic study showed that women who have experienced complete lobular involution are much less likely to develop breast cancer, because their lobules have been replaced by fat and connective tissue (Vierkant, et al, 2006). Women who have had hormone replacement therapy (HRT) are less likely to have complete involution, which may be why older women who have had HRT are more at risk for breast cancer.

At What Age Should a Woman Get Regular Mammograms?

Mammograms have long been viewed as key to breast cancer prevention. The U.S. government revised its mammogram guidelines in 2009, recommending that women over 50 (as opposed to 40) undergo mammographic screening every two years. Some private institutions, such as the Mayo Clinic, acknowledge the government’s change in stance, but still recommend that screening begin at a younger age.


The American Cancer Society. (2009). Breast cancer facts and figures 2009-2010. Retrieved on October 20, 2010 from

Breast Cancer Advice. (2006). Aging of breast tissue. Retrieved October 20, 2010 from

Breast Institute. (2010). Who gets breast cancer? Retrieved November 2, 2010, from

National Cancer Institute. (2008). Pregnancy and breast cancer risk. Retrieved October 20, 2010 from

Pruthi, S. (2009). Mammogram guidelines: What’s changed? Retrieved October 20, 2010 from

Vierkant, R., Hartmann, L., Pankratz, V., Anderson, S., Radisky, D., Frost, M., et al. (2006). Lobular involution: localized phenomenon or field effect? Retrieved October 29, 2010, from