This study is for people with a certain type of breast cancer, called HER2-positive, hormone receptor-positive breast cancer. "HER2-positive" means the cancer has a protein that makes cancer cells grow, and "hormone receptor-positive" means the cancer grows because of hormones like estrogen or progesterone. After surgery, participants will receive two types of treatments: a combination of drugs called PHESGO (trastuzumab and pertuzumab) and hormonal therapy. PHESGO is given as an injection under the skin.

Here are some key points about the study:

• Participants will receive PHESGO for 1 year and will continue hormonal therapy for about 5 years.
• The study involves regular doctor visits, lab tests, and answering questions about health.
• 375 people are expected to join, and the study tests the safety and effectiveness of the treatment.

To join, participants must meet specific requirements, like having had surgery to remove the tumor, not having had certain treatments before, and being able to follow study instructions. The study aims to see if this combination of treatments helps improve outcomes for people with this type of breast cancer.