Expect Questions About Atypical Hyperplasia as an Important Risk Factor for Breast Cancer

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Amy C. Degnim, MD

The younger a woman is when diagnosed with atypical hyperplasia, the more likely it is that breast cancer will eventually develop over the course of her lifetime.

—Amy C. Degnim, MD

A special report in The New England Journal of Medicine concluded that atypical hyperplasia of the breast “confers an absolute risk of later breast cancer of 30% at 25 years of follow-up.1” This is higher than previously recognized, and the report’s authors urged “more intensive screening and prevention strategies based on accurate risk estimates.”

In an interview with The ASCO Post, study coauthor Amy C. Degnim, MD, of the Department of Surgery, Mayo Clinic, Rochester, Minnesota, discussed how physicians can explain the findings to patients.

Start With the Risk Estimate

“The important thing is to start with how high the patient’s risk is,” Dr. Degnim said. The younger a woman is when diagnosed with atypical hyperplasia, the more likely it is that breast cancer will eventually develop over the course of her lifetime. “The data are strong enough that we can say that for any woman who has atypical hyperplasia, whether she is younger or older, a general estimate for her risk of developing breast cancer is about 1% per year,” Dr. Degnim stated. “So if you are a younger woman, you are expected to live longer, and so you would accumulate a higher risk compared to an older woman who has only a 10-year life expectancy.”

However, an individual woman’s risk estimate can be refined by knowing the number of sites (or ‘foci’) of atypical hyperplasia, with more foci adding up to more risk. Women with three or more foci of atypical hyperplasia have “had a risk of 47% at 25 years,” Dr. Degnim said, “or about 2% per year.”

Then Look at Managing the Risk

“The second point is to discuss options to manage a woman’s breast cancer risk through two different but related strategies­—surveillance and prevention. Surveillance approaches include looking closer to find a cancer if it is there (ie, MRI in addition to yearly mammography) or looking more frequently (alternating mammography and MRI every 6 months). Beyond looking to find very early cancers, prevention approaches take steps to prevent breast cancers from happening.”

Dr. Degnim explained that although current screening guidelines do not specifically recommend magnetic resonance imaging (MRI) for women with atypical hyperplasia of the breast, they do recommend MRI as an adjunct to mammography for women who have a lifetime risk of breast cancer of 20% to 25%. The risk for women with atypical hyperplasia meets or exceeds that level. Prevention medications involve the use of selective estrogen-receptor modulators and aromatase inhibitors. In certain cases, bilateral mastectomy might be considered, but that is generally avoided due to long-term physical and psychological risks.

‘The Other Way Around’

“The last point is understanding that atypical hyperplasia is not breast cancer,” Dr. Degnim stressed. “Because it is not cancer, and even though the data show that 30% of women with atypical hyperplasia developed breast cancer in 25 years, you can look at it the other way around—70% of them did not.”

“Even among those in whom breast cancer does develop,” the report concluded, “it can usually be treated successfully, and the diagnosis may occur at an age at which their risk of death from other causes is higher than their risk of death from breast cancer.” ■

Disclosure: Dr. Degnim reported no potential conflicts of interest.


1. Hartmann LC, Degnim AC, Santen RJ, et al: Atypical hyperplasia of the breast—risk assessment and management options. N Engl J Med 372:78-89, 2015.


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