Successful treatment of low-grade endometrial cancer in premenopausal women with an aromatase inhibitor after failure with oral or intrauterine progesterone

Introduction: Young women with endometrial intraepithelial hyperplasia or low-grade endometrial carcinoma are potential candidates for conservative fertility sparing therapy utilizing progesterone rather than hysterectomy. High-dose progesterone treatment is associated with 55–80% initial response but high relapse rates. Using aromatase inhibitors in conjunction with high-dose progesterone has largely been unstudied. Case descriptions: Three obese premenopausal women with endometrial cancer failed to respond to oral or intrauterine progesterone as first line therapy. Due to their desire to continue to pursue fertility sparing treatment options, an aromatase inhibitor was added to their treatment regimen. This resulted in resolution of their malignancy in each case. Discussion: In obese premenopausal women, the mechanism of malignant transformation in endometrial carcinoma is considered to be an association with relatively high levels of serum estrogen from peripheral conversion of androgens to estrone in adipose tissue with a deficiency in progesterone exposure due to chronic anovulation. Using aromatase inhibitors seems reasonable as an adjunct to progesterone given the high likelihood that this population has a significant proportion of their estrogen production coming from peripheral conversion in adipose tissue. This case series is unique in that each woman initially failed to respond to progesterone but had resolution when an aromatase inhibitor was added to their treatment regimen. This would suggest that obese women with low grade malignancy or hyperplasia who have no radiographic evidence of deep myometrial invasion, ovarian or retroperitoneal metastases and who wish to retain their fertility may be treated with intrauterine progesterone and an aromatase inhibitor.