Benign Breast Disease Increases Risk

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Benign breast disease isn’t cancer and isn’t life threatening. Cysts and fatty tumors are examples of benign breast disease. Still, certain types of benign breast disease have been shown to increase a woman’s risk of breast cancer in the future.

A study has found that two types of benign breast disease:

  • atypical ductal hyperplasia (ADH)
  • atypical lobular hyperplasia (ALH)

increase the risk of breast cancer in the same breast by about the same amount.

The study was published online on Jan. 30, 2014 by Cancer Prevention Research. Read the abstract of “Understanding the Premalignant Potential of Atypical Hyperplasia through Its Natural History: A Longitudinal Cohort Study.”

Both ADH and ALH are excessive growth of abnormal cells. Doctors call this “proliferative lesions with atypia.” In ADH, cells in the ducts (the pipes of the breast that drain the milk out to the nipple) are growing faster than normal and look abnormal. In ALH, cells in the lobules (the parts of the breast that make the milk) are growing faster than normal and look abnormal.

ADH has long been considered a direct precursor to breast cancer. In other words, a woman who was diagnosed with ADH was expected to develop breast cancer in the same breast at some point. ALH was considered slightly less dangerous -- women diagnosed with ALH were considered to have an overall higher risk of breast cancer, but weren’t necessarily expected to develop the disease.

These assumptions affect the way ADH and ALH are treated. Many doctors believe that ADH needs to be completely removed with surgery, while ALH doesn’t have to be completely removed.

In this study, researchers wanted to know more about the biology of ALH, as well as how much an ALH diagnosis increases breast cancer risk.

The researchers looked at medical records of women in the Mayo Benign Breast Disease Cohort, a registry of benign breast disease cases maintained by the Mayo Clinic. The study included information on:

  • 330 women diagnosed with ADH
  • 327 women diagnosed with ALH
  • 32 women diagnosed with both ADH and ALH

All the women were diagnosed with benign breast disease between 1967 and 2001.

Overall, 143 women in the study developed invasive breast cancer:

  • 60 women diagnosed with ADH were later diagnosed with invasive disease
  • 75 women diagnosed with ALH were later diagnosed with invasive disease
  • 7 women diagnosed with both ADH and ALH were later diagnosed with invasive disease

About 66% of the cancers developed in the same breast as the benign breast disease for both the ADH and ALH groups. This means that ADH and ALH increased risk of breast cancer in the same breast by the same amount.

The time it took for breast cancer to develop varied depending on the type of benign breast disease:

  • 40% of women diagnosed with ADH and about 30% of women diagnosed with ALH developed breast cancer within 5 years of benign disease biopsy
  • 31.7% of women diagnosed with ADH and 23% of women diagnosed with ALH developed breast cancer 6 to 10 years after benign disease biopsy
  • 16.7% of women diagnosed with ADH and 23% of women diagnosed with ALH developed breast cancer 11 to 15 years after benign disease biopsy
  • 11.7% of women diagnosed with ADH and 23% of women diagnosed with ALH developed breast cancer more than 15 years after benign disease biopsy

If you’ve been diagnosed with either ADH or ALH, your risk of developing breast cancer is higher than average. How much higher depends on the characteristics of the benign disease, as well as your family history and other health factors. Together, you and your doctor can consider all the aspects of your unique situation and develop a risk reduction plan that makes the most sense for you.

Visit the Breast Cancer Risk Factors: Certain Breast Changes page in the Breastcancer.org Lower Your Risk section to learn more about benign breast diseases and steps you can take to keep your risk as low as it can be.


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