Models and the Early Detection of Disease: Methodological Considerations

Abstract

There is increasing interest in using special diagnostic examinations to detect a potential disease or condition in an individual who has no signs or symptoms. The motivation behind such efforts is that earlier detection, when combined with an effective therapy, will lead to enhanced benefit. The benefit is usually reflected in a higher cure rate or longer survival. In ordinary circumstances most cancers—especially solid tumors, are usually diagnosed when an individual experiences pain or a vital organ is not functioning properly or a “lump” beneath the skin is palpated. Diagnosing a disease without these signs or symptoms often results in the disease being diagnosed in an earlier stage. Many therapies are enhanced when given to earlier disease stage patients. The primary treatment modalities for most cancer sites is surgery and/or radiation. These are essentially treatments which are targeted at localized disease. If the cancer site has metastasized, then resecting or radiating the primary tumor will not result in cures. Effective chemotherapy can be significantly enhanced if the metastatic disease consists of microscopic cells which have not seriously interfered with a vital organ.