LAUSR

Introduction/Background Hormonal therapy in endometrial cancer (EC) is used for patients who wish to preserve fertility and for patients with advanced or recurrent disease in a palliative setting. Since estrogen plays an important role in the development of most ECs, anti-estrogenic therapy is an alternative treatment to the more frequently used progestin therapy. However, there is limited data on the response rates and toxicity of anti-estrogens in EC. Therefore, we performed a systematic review to investigate response rates and toxicity in anti-estrogen therapy in patients with EC. Methodology A systematic search in electronic databases was performed to identify studies on selective estrogen receptor modulators (SERM) and down-regulators (SERD) and aromatase inhibitors that reported on response rates among EC patients. Outcome in estrogen receptor (ER) positive and negative disease was assessed independently. Results Fifteen studies were included of which ten investigated anti-estrogen monotherapy and six investigated a combination of anti-estrogenic drugs with either progestin or targeted treatment. Thirteen prospective studies and two case series were included. The median age of the patients in the included studies ranged from 61–71 years and the proportion of low grade tumors ranged from 38–80%. The RR for tamoxifen ranged from 10–53%, for other SERMs and SERDs 9–31%, for aromatase inhibitors from 8–9%, for combined tamoxifen/progestin treatment 19–58% and for combination of anti-estrogenic treatment with mammalian target of rapamycin (mTOR) inhibitors 14–31%. Toxicity consisted of thrombotic events in 2–6% in all therapies except for the anti-estrogenic/mTOR combination. Conclusion Tamoxifen or a combination of tamoxifen and progestin should be the preferred choice when selecting anti-estrogenic treatment because the RRs are similar to progestin treatment and the toxicity is low. The response can be optimized by selecting patients with endometrioid tumors and positive estrogen receptor status, which should be based on a pretreatment biopsy. Disclosure Nothing to disclose.