March 19, 1999

Estrogen no added risk for women with benign breast tumors

Estrogen no added risk for women with benign breast tumors


William Dupont, Ph.D., found that estrogen therapy doesn't raise the risk of breast cancer in women with histories of benign breast disease. (photo by Donna Jones Bailey.)

A new study by Vanderbilt University Medical Center researchers identifies another piece in the puzzle of risks associated with hormone replacement therapy for menopause.

William D. Dupont, Ph.D., professor of Preventive Medicine, and colleagues report in the March 15 issue of Cancer that estrogen replacement therapy (ERT) does not significantly elevate the risk of breast cancer in women with histories of benign breast disease.

ERT relieves most of the symptoms of menopause and there is compelling evidence that it protects against coronary heart disease and osteoporosis. Long-term ERT, however, may be associated with a mild elevation in breast cancer risk for all women, and ERT without co-administered progestins increases the risk of endometrial cancer.

Women with a history of benign breast disease already face a 40-260 percent increase in breast cancer risk, depending on the type of breast lesion. It was previously thought that these women might have an even greater elevation in breast cancer risk if they used ERT. Until this study, however, little information has been available regarding the added risk for this group.

"The study was very reassuring," Dupont said. "We find no evidence that the breast cancer risk already associated with these patients is further elevated by taking estrogen."

The patients studied by Dupont and colleagues are part of the Nashville Breast Cohort. These women originally underwent breast biopsies revealing benign breast disease between 1952 and 1978 at Baptist, St. Thomas, and Vanderbilt University Hospitals.

"One of the pieces of information that we collected on follow-up was the use of ERT," Dupont said. "What makes our database unique is the fact that we have this information for women for whom we know precisely what type of benign breast disease they had."

The Nashville Breast Cohort includes nearly 10,000 women, making it one of the largest groups of its kind. Dupont and Dr. David L. Page, professor of Pathology and Preventive Medicine, have spent 20 years studying breast cancer risk factors for these women.

Their work has included redefining and diagnosing the types of benign breast disease by carefully studying the histologic slides made at the time of biopsy.

"In the past it was very standard to diagnose any woman who had a breast biopsy and didn't have breast cancer as having fibrocystic disease, Dupont said. "One of our major contributions has been to replace the notion of fibrocystic disease as a pathologic entity with other terms for which we have been able to carefully associate different levels of breast cancer risk."

Breast cancer risk is a legitimate concern for women; breast cancer is the second leading cause of cancer death in women. Death from all cancers is still second to heart disease, which is the number one killer of women as well as men.

"The bottom line here is that as long as women understand what the potential risks are, the benefits of estrogen to the heart and bone certainly make ERT a rational choice."

Dupont and colleagues conclude that ERT is not contraindicated in women with previous benign breast disease, certainly good news for women in this group as they face the decision to begin ERT at menopause.

This study was supported by the National Cancer Institute.