Herein, in this review, we explored recent information on the development and use of GnRH analogs, such as agonists (defined in this work as GnRHa by hGnRH-I agonists and GnRHa-II by hGnRH-II agonists), antagonists (defined in this work as GnRH-ant by hGnRH-I antagonists and GnRH-ant-II by hGnRH-II antagonists), non-peptide GnRH antagonists, and cytotoxic analogs of GnRH and their possible implications as antitumor agents against BC. This evidence concerns the gene GNRH1 and breast cancer.