Therapeutics refers to treatment and care of a patient for the purpose of both preventing and combating disease or alleviating pain (减轻痛苦) or injury. The term comes from the Greek therapeutikos, which means "inclined to serve." PREVENTIVE MEDICINED 2 The rationale for preventive medicine (预防医学) is to identify risk factors in each individual and reduce or eliminate those risks in an attempt to prevent disease. Primary prevention (初级预防) is the preemptive behavior that seeks to avert disease before it develops, for example ,vaccinating children against diseases. Secondary prevention is the early detection of disease or its precursors before symptoms appear, with the aim of preventing or curing it. Examples include regular cervical Papanicolaou test screening and mammography. Tertiary prevention is an attempt to stop or limit the spread of disease that is already disease present. Clearly, primary prevention is the most cost-effective method of controlling disease.