Benign breast conditions (also known as benign breast diseases) are non-cancerous breast disorders.
Some of these conditions increase the risk of breast cancer and others do not.
To assess breast cancer risk, benign breast conditions are classified as:
Proliferative breast conditions are not cancerous, but they do increase the risk of breast cancer [171-173].
The most common type of proliferative breast condition is hyperplasia.
There are 2 types of hyperplasia: usual hyperplasia (more common) and atypical hyperplasia (less common).
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 [171-172].
In atypical hyperplasia, the proliferating (dividing) cells look abnormal.
Atypical hyperplasia is less common than usual hyperplasia.
Women with atypical hyperplasia have about 3-5 times the breast cancer risk of women without a proliferative breast condition [171-173].
One study found women diagnosed with atypical hyperplasia had about a 29 percent chance of developing breast cancer within 25 years .
For a summary of research studies on hyperplasia and breast cancer, visit the Breast Cancer Research Studies section.
For women with atypical hyperplasia who also have a greater than 20 percent 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 have a greater than 20 percent lifetime risk of invasive breast cancer :
This medical care helps ensure if breast cancer does develop, it's caught early when the chances of survival are highest.
NCCN recommends women with atypical hyperplasia who have a less than 20 percent lifetime risk of invasive breast cancer and women with usual hyperplasia get the same breast cancer screening as women at average risk.
Learn more about breast cancer screening for women at higher risk.
It’s strongly recommended women with atypical hyperplasia (but not usual hyperplasia) take a risk-lowering drug (tamoxifen or raloxifene) to lower their risk of developing breast cancer .
These drugs can lower the risk of breast cancer in women with atypical hyperplasia by 86 percent .
Learn more about risk-lowering drugs.
Non-proliferative benign breast conditions (such as cysts) do not increase the risk of breast cancer.
Learn more about benign breast conditions.
Benign Breast Conditions