In the largest randomized, controlled trial to date on the subject, researchers found that estrogen-only hormone replacement therapy (ERT) does not increase the risk of recurrence of endometrial cancer in women surgically treated for the condition.
Conducted over a 5-year period, the study included over 1,200 women who had hysterectomy and bilateral salpingo-oophorectomy for stage I or II endometrial cancer and who were experiencing symptoms of menopause; 618 women received ERT and 618 received placebo.
Both groups experienced few disease recurrences (1.9% on ERT, 1.6% on placebo) or endometrial cancer deaths (0.5% on ERT, 0.6% on placebo), and both groups had a low incidence of new cancer diagnoses of any type, including breast cancer. The survival rate for the study population was 96.6%.
Barakat RR, Bundy BN, Spirtos NM, et al. A prospective randomized double-blind trial of estrogen replacement therapy versus placebo in women with stage I or II endometrial cancer: a Gynecologic Oncology Group Study. Abstract 1.