Findings in a recent study published in the journal Cancer indicate that after five years Estrogen Replacement Therapy (ERT) had no adverse effect on survival or compromised disease-free states among women with a history of treated localized breast cancer.

ERT has been shown to have important health benefits for many post-menopausal women, including skeletal, cardiovascular and quality of life improvements. Concerns over the risks of ERT for some women, particularly those with a history of breast cancer, have tempered its use in those populations.

In theory ERT may reactivate breast cancer cells but no studies have yet linked ERT to breast cancer recurrence. Women with breast cancer often undergo premature ovarian failure because of chemotherapy and potentially may benefit from ERT. To date only a few small prospective and retrospective studies have been conducted and suggest that ERT may be safe in women with a history of treated breast cancer.

Vassilopoulou-Sellin et al conducted a randomized, prospective clinical trial to evaluate the safety and efficacy of ERT in patients with a history of treated stage I or II localized breast cancer. Women with a history of known estrogen receptor (ER)-positive tumors were specifically excluded from this study. Seventy-seven women participated in the randomized arm for which 34 received ERT and 43 did not. An additional 222 women participated in the non-randomized arm of the study for which 22 received ERT and 200 did not.

No statistically significant differences between the clinical prognostic characteristics of randomized and nonrandomized patients were observed. Participants were evaluated every three months for two years and every six months for an additional three years with clinical and laboratory assessments, including lipid profile, FH, FHS, and estradiol levels, at each visit. Bone Mineral Density (BMD) was measured at baseline and annually for five years.

There was no significant difference in survival after five years between women who received ERT and those who did not. Analysis of the randomized group showed no differences in disease free survival among women receiving ERT and those who did not or among those women with a history of ER-negative tumors. Analysis of all 299 participants showed similar findings. In fact, patients receiving ERT were more likely to enjoy breast cancer-free survival. New or recurrent breast cancer developed in 33 (13.5%) women in the no-ERT arm and contralateral, new breast cancer developed in 2 (3.6%) women on ERT. No difference in disease free survival was observed among participants with ER-negative tumors. There were no deaths and no difference between ERT and no-ERT groups in the development of other cancers.

There was modest improvement in bone density and lipid profiles among women treated with ERT. After five years there was significant beneficial effect on BMD of the hip (P=0.0001) and significant improvement in HDL cholesterol in the ERT group.

The authors conclude that this study "provides prospective data with much longer follow-up than previous series and reinforced the notion that ERT does not compromise disease free states in patients with curatively treated breast cancer." The increasing evidence of ERT safety in women with a history of treated breast cancer should encourage significantly larger trials.

The authors add, "larger prospective, randomized trials with appropriate statistical power are clearly very important to define the safety of ERT in this setting and, perhaps, modify current standards of care for women with a history of treated primary breast cancer."

SOURCE:
Cancer, November 1, 2002