Women under the age of 50 who have atypical hyperplasia of the breast are nearly seven times more likely to develop breast cancer than women in the general population, irrespective of family history. These results were presented at the 2008 San Antonio Breast Cancer Symposium.

Studies have suggested that risk of breast cancer is higher among women with particular types of benign breast disease; however the risks among varying benign diagnoses have not been well defined. The importance of establishing specific risks is to gain understanding of how best to monitor these women so that breast cancer may be detected and treated in its earliest stages while minimizing false-positives and over-screening.

To explore the relationship between benign breast disease and breast cancer among women under the age of 50, researchers at the Mayo Clinic evaluated information from more than 4,000 women with benign breast disease. Two percent had been diagnosed with atypical hyperplasia, 26% had been diagnosed with proliferative disease without atypia, and 72% had been diagnosed with non-proliferative disease. Data from these women was compared with data derived from the NCI Surveillance, Epidemiology, and End Results (SEER) database.