Estrogen Replacement Therapy Does Not Increase Breast Cancer Recurrence

WASHINGTON—Fear that hormones may increase the risk of cancer recurrence has long discouraged US physicians from recommending estrogen replacement therapy (ERT) to breast cancer survivors, despite its proven advantages for health and quality of life.

But this policy needs re-examination in light of results from the longest-running study yet done of women who have taken estrogen after breast cancer, said George N. Peters, MD, University of Texas Southwestern Breast Center, Dallas.

The results of this study show that these women have no higher risk of breast cancer recurrence than women who have not taken ERT, Dr. Peters said at the 54th Annual Cancer Symposium of the Society of Surgical Oncology (SSO).

With more women becoming postmenopausal at younger ages because of breast cancer treatment, "we must continue to question whether it is appropriate to continue excluding them from the known benefits of ERT," he said.

These benefits include better bone density, less heart disease, less genitourinary morbidity, cognitive advantages, and, in some cases, a generally improved sense of well-being, he said.

Between February and August 1995, researchers interviewed 607 breast cancer survivors about their experience with ERT. Of these, 67 had used estrogen in some form after being diagnosed with breast cancer. Eleven women whose only exposure had been vaginal creams were excluded from the study. The remaining 56 women, who had used birth control pills, conjugated estrogens, or estradiol patches, were followed prospectively.

In addition, their medical records were analyzed for their disease stage and estrogen-receptor (ER) status, the type of surgical and adjuvant treatment they had received, the type of ERT they had used, the length of time they had used it, how soon after cancer diagnosis it had begun, whether they had experienced any cancer recurrences, and their final outcome.

The time elapsed since the breast cancer diagnosis ranged between 4.7 and 38.9 years (median, 12.8). The length of ERT use after cancer diagnosis ranged from 1.0 to 20.9 years (median, 6.4). In 38% of cases, women began taking estrogen less than 2 years after diagnosis.

Of the women whose ER status was known, 74% were positive. Most of the women had good-prognosis disease. Pathologic disease stages were 25% stage 0, 46% stage I, 25% stage II, and 4% stage unknown; 48% of the women had received adjuvant therapy, either chemotherapy or hormonal therapy.

Fifteen-year actuarial disease-free survival within the group that had received ERT was 92.5% (see Figure), with a single local recurrence at 13.7 years and a single cancer in the contralateral breast at 9.6 years. The women had experienced no regional or distant recurrences or cancer deaths.

ERT appears to have no adverse effect on breast cancer survivors’ outcomes, Dr. Peters concluded, adding that be believes that physicians should inform women of estrogen’s "proven benefits" and "theoretical risks." This approach would represent a significant change from current attitudes, he observed.

Of women interviewed in a previous study, 38% said they didn’t "want to consider" ERT; 33% said they were "afraid" of it; and 17% indicated they had been discouraged from using it by their physicians. When women with early breast cancers inquire about ERT, Dr. Peters said, physicians should tell them that "there is no clear evidence that using it would put them at risk."