Women with benign breast disease have a higher risk for breast cancer

A study led by Mayo Clinic Cancer Center adds evidence to a growing body of knowledge that shows women with benign breast disease have a higher risk for breast cancer, and that certain types of breast disease may predict the near-term development of breast cancer. The findings will be published in the July 21 issue of The New England Journal of Medicine.

"Our findings indicate a link between select types of benign breast lesions and the later development of breast cancer," says Lynn Hartmann, M.D., Mayo Clinic oncologist and lead investigator of the study. "Women who have a breast biopsy that is benign must discuss the possibility of additional risks with their doctors."

Benign breast disease refers to any lumps or mammographically-detected abnormalities that have been biopsied and found to not contain cancerous cells. Each year in the United States it is estimated that more than 1 million women have a breast biopsy with benign findings, and Dr. Hartmann encourages clinicians to look more closely at the type of lesions they find. The Mayo team is evaluating various possible risk factors for a later breast cancer, including age at benign biopsy, family history of breast cancer and the pathologic findings of the benign lesion. "Our goal is to do a better job of risk prediction for women with various types of benign breast conditions," says Dr. Hartmann.

Dr. Hartmann and her co-investigators were heartened to find convincing evidence that women with the most common, non-proliferative forms of benign findings had no increased risk of developing breast cancer -- as long as they did not have a strong family history of breast cancer. However, for proliferative and atypical types, the opposite was true, and these lesions pointed to an increased risk of a future breast cancer, even when the family history of breast cancer was negative. Dr. Hartmann and her colleagues say continued studies of this kind are necessary to help understand the process of breast cancer development.

The study population of 9,087 women was drawn from the Mayo Clinic Surgical and Pathology Indices, identifying women ages 18 to 85, who had a biopsy of a benign breast lesion during a 25-year period from Jan. 1, 1967, through Dec. 31, 1991. Family histories were obtained at time of follow-up and from Mayo medical record questionnaires.

All benign breast samples were evaluated by a breast pathologist unaware of initial diagnoses or patient outcomes and assigned to one of three categories of benign breast lesions -- non-proliferative, proliferative and atypical. This information was used to link the risk of subsequent development of breast cancer to specific types of lesions.

In addition to Dr. Hartmann, members of the Mayo Clinic research team included Marlene Frost, Ph.D., Wilma Lingle, Ph.D., Amy Degnim, M.D., Karthik Ghosh, M.D., Robert Vierkant, Shaun Maloney, V. Shane Pankratz, Ph.D., David Hillman, Vera Suman, Ph.D., Jo Johnson, Celine Vachon, Ph.D., L. Joseph Melton III, M.D., and Daniel Visscher, M.D. They were joined by Thomas Sellers, Ph.D., H. Lee Moffitt Cancer Center and Research Institute, Tampa, Fla.; Cassann Blake, M.D., Wayne State University, Detroit; and Thea Tlsty, Ph.D., University of California, San Francisco.