Celvestrant PFS Injection relieves the symptoms of breast cancer such as breast lumps, bloody discharge from nipple or changes in the shape or texture of the breast. It works by altering the production of those hormones in the body that are essential for the growth and spread of breast cancer. It may also interact with other hormones or have a direct effect on the cancer to stop its growth. It is given as an injection by a doctor or nurse and should not be self-administered. Follow your doctors instructions carefully.