This study is testing a new medicine called elacestrant against regular hormone treatment for breast cancer. The focus is on people with early breast cancer that might come back, and they have a special type of cancer called ER+ (Estrogen Receptor-positive) and HER2- (Human Epidermal Growth Factor-2 negative). The study wants to see if elacestrant works better. People can join if they have a type of breast cancer that is positive for estrogen but not for HER2, have been on hormone therapy for 2-5 years, and are at a high risk of their cancer coming back. They cannot participate if they have had other types of breast cancer or other cancers recently. This study helps us learn more about which treatment is best for keeping breast cancer from returning.

• Participants must have a type of breast cancer that has a high risk of coming back.
• The study lasts until either treatment stops working or it is no longer safe.
• People will be compared between those receiving elacestrant and those on standard therapy.