Key takeaways
Goserelin (Zoladex) and tamoxifen (Nolvadex) are both used to treat hormone receptor-positive (HR+) breast cancer, but they belong to different medication classes. Goserelin is a gonadotropin-releasing hormone (GnRH) agonist, while tamoxifen is a selective estrogen receptor modulator (SERM). Goserelin is administered as an implant under the skin every 4 weeks or every 3 months, whereas tamoxifen is an oral tablet usually taken once daily. Goserelin is also used for prostate cancer and endometriosis, while tamoxifen is also used to lower the risk of breast cancer in high-risk females. Goserelin can cause side effects like hot flashes and diarrhea, and it may weaken bones. Tamoxifen can also cause hot flashes and weaken bones and commonly causes vaginal discharge. Tamoxifen increases the risk of blood clots and uterine cancer. Tamoxifen is available as a lower-cost generic, whereas goserelin does not have a generic version. Both medications require careful monitoring for side effects and interactions, but tamoxifen has more known interactions.
