Yonsa works by reducing androgen production in the body. Androgens are male hormones that can promote tumor growth in the prostate gland.
Yonsa is used together with steroid medication (prednisone or methylprednisolone) to treat prostate cancer that has spread to other parts of the body.  Yonsa is used in men whose prostate cancer cannot be treated with surgery or other medicines.
Yonsa may also be used for purposes not listed in this medication guide.
