Breast Cancer Risk Factors: Hyperplasia and Other Benign Breast Conditions

Benign breast conditions (also called benign breast diseases) are non-cancerous breast disorders. They may be found on a mammogram and may be diagnosed with a biopsy.

Some benign breast conditions are linked to an increased risk of breast cancer and others are not.

To assess breast cancer risk, benign breast conditions are classified as:

• Proliferative (those with quickly growing cells)
• Non-proliferative (those without quickly growing cells)

Learn about other factors linked to the risk of breast cancer.

Proliferative breast conditions

Proliferative breast conditions are not cancerous, but they are linked to an increased risk of breast cancer [188-191].

The most common proliferative breast condition is hyperplasia.

There are 2 types of hyperplasia: usual hyperplasia (more common) and atypical hyperplasia (less common).

Usual hyperplasia

In usual hyperplasia (the most common form of hyperplasia), the proliferating (dividing) cells look normal under a microscope.

Women with usual hyperplasia have about twice the breast cancer risk of women without a proliferative breast condition [188-189].

For a summary of research studies on usual hyperplasia and breast cancer, visit the Breast Cancer Research Studies section.

Atypical hyperplasia

In atypical hyperplasia, the proliferating (dividing) cells look abnormal.

Atypical hyperplasia is less common than usual hyperplasia.

Women with atypical hyperplasia have about 3 to 5 times the breast cancer risk of women without a proliferative breast condition [188-191].

For a summary of research studies on atypical hyperplasia and breast cancer, visit the Breast Cancer Research Studies section.

Breast cancer screening for women with atypical hyperplasia

For women with atypical hyperplasia who also have a 20% or greater lifetime risk of invasive breast cancer, there are special breast cancer screening recommendations. (Estimate your lifetime risk or learn more about risk.)

The National Comprehensive Cancer Network (NCCN) recommends women with atypical hyperplasia who also have a 20% or greater lifetime risk of invasive breast cancer [163]:

• Have a clinical breast exam every 6-12 months
• Have a mammogram with digital breast tomosynthesis every year, starting at age 30
• Talk with a health care provider about screening with breast MRI every year, starting at age 25

This medical care helps make sure if breast cancer does develop, it’s caught early when the chances of survival are highest.

Learn more about breast cancer screening for women at higher risk.

Risk reduction for women with atypical hyperplasia

The NCCN strongly recommends women with atypical hyperplasia (but not usual hyperplasia) take a risk-lowering drug (such as tamoxifen) to lower their risk of developing breast cancer [54].

These drugs can lower the risk of breast cancer in women with atypical hyperplasia by about 86% [54].

Learn more about risk-lowering drugs.

Non-proliferative breast conditions

Non-proliferative breast conditions (such as cysts) are not linked to an increased risk of breast cancer.

Learn more about benign breast conditions. 

Updated 04/24/24