Breast surgery is a form of surgery performed on the breasts. There are many types of breast surgery, including: breast augmentation; breast reduction surgery; breast-conserving surgery (less radical than mastectomy); lumpectomy; mastectomy; and mastopexy (breast lift). Breast augmentation surgery involves the implantation of breast implants for fuller breasts. Women choose to have breast augmentation surgery to improve their self-image. A breast implant alters the size and shape of the breasts of a person. There are two primary types of breast implants: saline-filled and silicone-gel-filled. Saline implants have a silicone elastomer shell filled with sterile saline liquid. Silicone gel implants have a silicone shell filled with a viscous silicone gel. Breast reduction or a reduction mammoplasty is a common surgical procedure, which involves reducing the size of breasts by excising fat, skin, breast implants and glandular tissue; it may also involve a procedure to counteract drooping of the breasts. As with breast augmentation, this procedure is for women, also on men afflicted by gynecomastia. Breast-conserving surgery is a less radical cancer removal surgery than mastectomy. During breast-conserving surgery, a surgeon removes the damaged part of the breast tissue during surgery, as opposed to the entire breast, much like a lumpectomy. A lumpectomy is a common surgical procedure performed by a surgeon who removes a discrete lump, usually a tumor, from the breast of an affected man or woman. A lumpectomy is a relatively non-invasive procedure because it does not involve the removal of all breast tissue. Unlike a mastectomy, a lumpectomy is a viable means of "breast conservation" or "breast preservation" surgery. A mastectomy is a surgery where a doctor removes one or both breasts, partially or completely. During a mastectomy, a surgeon removes all of the breast tissue, which helps treat cancer. In some cases, women and some men at high risk of breast cancer undergo the operation voluntarily, that is, to prevent cancer rather than treat it. A mastopexy or breast lift, refers to an elective surgical operation designed to lift or change the shape of the breasts. A breast lift repositions the areola and nipple, while lifting the breast tissue and removing excess sagging skin.