Benign Breast ConditionsFact Sheet
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 increase the risk of breast cancer [119-121].
The most common type of proliferative breast condition is hyperplasia. There are two 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 two times the breast cancer risk of women without a proliferative breast condition [119-121].
In atypical hyperplasia, the proliferating (dividing) cells look abnormal. Atypical hyperplasia is less common than usual hyperplasia.
Women with atypical hyperplasia have about four to five times the breast cancer risk of women without a proliferative condition [119-121]. 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.
Non-proliferative benign breast conditions (such as cysts) do not increase the risk of breast cancer.
Learn more about benign breast conditions.
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