Without screening, diagnosis of disease only occurs after symptoms develop. However, disease frequently begins long before symptoms occur, and even in the absence of symptoms there may be a point at which the disease could be detected by a screening test. The time interval between possible detection by screening and later detection after symptoms is the "detectable pre-clinical phase" or DPCP. We hope that detection of disease in the DPCP will lead to earlier treatment and that this, in turn, will lead to a better outcome. However, this is not always the case. There has been much controversy regarding the age at which routine mammography screening should begin in order to screen for breast cancer. More recently, there has been controversy about whether PSA (prostate-specific antigen) screening should be used at all in men.

Learning Objectives

After completing this module, the student will be able to: