Microscopic Change May Double Breast Cancer Risk For Some Women

Women with a certain microscopic abnormality known as a "radial scar" were twice as likely to get breast cancer, report researchers from the Beth Israel Deaconess Medical Center and Brigham and Women's Hospital in Boston. The researchers reviewed the benign breast biopsies of nearly 1,400 women enrolled in the landmark Nurses Health Study, which is based at Brigham and Women's Hospital.

The study is published in the February 11 issue of the New England Journal of Medicine.

Annually, an estimated 1 million women in the United States undergo a breast biopsy, the only sure way to know whether a breast lump or a suspicious area on a mammogram is cancer. The good news for most women is that two out of three breast biopsies are not cancerous. But even a benign pathology report can tell a woman something about her future risk of breast cancer.

"Most women who have a benign breast biopsy are at little or no increased risk of subsequent breast cancer," says Stuart Schnitt M.D., pathologist at Beth Israel Deaconess and senior author of the study. "However, a small proportion are at a higher level of risk. The findings of this study help refine our understanding of which women might be at greater risk." Schitt is also an associate professor of pathology at Harvard Medical School.

The study confirms earlier reports about a suspected relationship between radial scars and breast cancer. Radial scars are tiny abnormal tissue changes found deep within breasts. In this study, radial scars were detected with a microscope in biopsies taken to check for other breast abnormalities. Larger radial scars can be detected by mammography.

Doctors are not sure how radial scars develop in the breast. They cannot be seen with the naked eye, nor can they be felt in a breast exam. Their name comes from the way they look under the microscope. Compared to normal breast tissue, which shows random clusters of ducts surrounded by supporting connective tissue, radial scars have a core of apparently scarred tissue surrounded by ducts radiating out from the center. Some studies have suggested a link between radial scars and breast cancer, but others have been inconclusive. This is believed to be the largest study looking at the risk of subsequent breast cancer in women with radial scars.

In this study, pathologists found radial scars in specimens of nearly 100 of the women with benign breast biopsies, or about 7 percent of the women studied. Statistically, the abnormality doubled their risk of breast cancer independently of other tissue abnormalities. The risk of breast cancer was similar for either breast, regardless of the breast biopsied.

The research builds on earlier research findings that benign microscopic abnormalities fit into three risk categories: nearly none, nearly double, and nearly five times the relative risk of breast cancer. For women with other risky abnormalities, radial scars further increased the risk of breast cancer.

"Now that we better understand its significance, the presence of radial scars should be formally incorporated into pathology reports," says medical oncologist Nadine Tung, director of the Cancer Risk and Prevention Program at Beth Israel Deaconess. "along with other defined risk factors, the presence of radial scars can be used to assess a woman's risk of developing breast cancer in the future." Tung helps women assess their risk of breast cancer and counsels them with strategies to reduce the risk.

In their paper, Schnitt and his colleagues recommend that pathologists specifically report the presence of radial scars in benign breast biopsies. They also advise that women with radial scars detected by biopsies should undergo the same regular clinical and mammographic follow-up recommended for other patients with benign breast lesions associated with a moderately increased risk of breast cancer in either breast.

Both Beth Israel Deaconess Medical Center and Brigham and Women's Hospital are major clinical, research and teaching affiliates of Harvard Medical School. The Nurses Health Study is based at Brigham and Women's Hospital. It is considered the largest study of women to evaluate lifestyle factors, such exercise and diet, on women's health.