Individuals respond differently to the same drug. Besides age, other factors that affect the individual's response to drugs are the presence of disease, degree of nutrition or malnutrition, genetics, and the presence of other drugs in the system. Indications for Use 13 The purpose of using drugs is to relieve symptoms, treat infection, reduce the risk of future disease, and destroy selected cells such as in the chemotherapeutic treatment of cancer. SURGICAL THERAPY Wound Treatment 14 Wound closure begins with a thorough cleansing of the wound and the installation of a local anesthetic (局部麻醉剂) . 15 Sutures are the most commonly used means of wound closure, although staples and adhesive tissue tape may be more appropriate in certain circumstances. Sutures used include silk, nylon, and absorbable sutures made of catgut or a synthetic material (合成材料) . 16 Dressings protect the wound from external contamination and facilitate absorption of drainage. In a surgical wound, an occlusive dressing is applied, consisting of gauze held in place by tape. Surgical Extirpation 17 Extirpation is the complete removal or eradication of an organ or tissue and is a term usually used in cancer treatment or in the treatment of otherwise diseased or infected organs. The aim is to completely remove all cancerous tissue, which usually involves removing the visible tumor plus adjacent tissue that may contain microscopic extensions of the tumor.