The effects of goserelin combined with tamoxifen on hormone levels and endometium thickness

This study investigated the combined treatment of tamoxifen (nolvadex) and goserelin (zoladex) in women diagnosed with early stage hormone receptor positive breast cancer.

Growth of hormone receptor positive (HR+) breast cancer is stimulated by the hormone estrogen. Tamoxifen is an oral drug commonly used to treat HR+ breast cancer. Tamoxifen prevents estrogen from attaching to complexes on the surface of the cancer cell called estrogen receptors. However in the lining of the uterus (called the endometrium) tamoxifen actually enhances the interaction between estrogen and its receptor. As a result, tamoxifen has been linked to the development of endometrial cancer. Goserelin is an injectable drug also commonly used in the treatment of HR+ breast cancer. Goserelin lowers the amount of estrogen produced, resulting in the inhibition of cell growth.

In this study a total of 110 women diagnosed with early stage HR+ breast cancer were recruited. 56 patients were randomly assigned to receive active treatment with a combination of tamoxifen and goserelin. The remaining 54 patients were assigned to the control treatment group and received treatment with tamoxifen alone. Hormone levels in the blood, as well as breast tissue density and endometrial thickness (an indicator for the level of growth stimulation) were measured at various times up to 18 months after the beginning of treatment.

Results showed that patients treated with goserelin and tamoxifen had lower hormone levels in the blood throughout the study. Breast density and endometrial thickness were also significantly lower in patients receiving combined treatment compared to those treated with tamoxifen alone.

Overall, this trial showed that combination treatment with goserelin and tamoxifen lowers blood hormone levels, breast tissue density and endometrial thickness more effectively than tamoxifen alone.

Although this study provided information about important factors which increase the risk of developing new or recurring cancers, this study only followed patients for a short period of time and no information was provided regarding the actual risk of developing additional tumors. This study was funded in part by the pharmaceutical company AstraZeneca which manufactures both goserelin (zoladex) and tamoxifen (nolvadex).

Consult with your physician regarding the possible benefits and risks of goserelin treatment.