Immunologic approaches to tumor markers: Assays, applications, and discovery

This chapter reviews the design, performance, and application of tumor marker assays; interferences; specific tumor markers; and the impact of new technologies on the discovery of novel tumor markers. In most populations, there is an overlap between the noncancer and cancer groups, since individuals without cancer may exhibit elevated levels of a marker and some individuals with cancer may not show elevations in a particular marker. The possible applications for tumor markers include screening, diagnosis, monitoring of therapy, detection of disease recurrence, and determination of prognosis. The prevalence of most cancers in the population is low, but with the inappropriate sensitivity and specificity of some tumor marker assays, false-positive results may be generated. Surgical removal of the tumor should result in a dramatic fall of the tumor marker, consistent with its half-life. Antibodies can be employed for specific targeting of analytes in many complex biological matrices, including blood (whole or a portion thereof), urine, and other fluids. The specificity of the antigen-antibody interaction, coupled with the exquisite sensitivity of enhanced signal detection methods available today, makes immunoassays the method of choice in laboratory medicine.