Researchers at Mayo Clinic have found that a type of benign breast disease (BBD), known as atypical hyperplasia, substantially increases a young woman's risk of developing breast cancer, even if there is no history of breast cancer in her family.
The researchers said that the women they studied with this kind of benign breast disease had a relative risk of developing breast cancer that was almost six times greater than women with no evidence of the disease.
In the study, the authors found that young women diagnosed with two other forms of benign breast disease were at much less risk than patients with atypical hyperplasia.
Those with non-proliferative disease were only slightly at increased risk (1.2 times, or .2 percent higher than normal) and women with proliferative disease without atypia had a risk that was doubled.
A family history of breast cancer increased risk in these two groups of patients, but only slightly.
The average age of benign breast disease diagnosis in the 4,460 women included in this study was 39 years old. Within that group, 326 women eventually - sometimes decades later - developed breast cancer.
"Breast cancer is the leading cause of cancer death in women age 25 to 49, and these young patients also have worse overall survival and increased risk of cancer coming back compared to older women, so it is important that we try to understand how the cancer develops and the measures that help prevent it," said the study's lead author Karthik Ghosh, M.D.
The study was presented at the Cancer Therapy and Research Center-American Association for Cancer Research (CTRC-AACR) San Antonio Breast Cancer Symposium.