Diagnosis and therapeutic relevance of micrometastases.

The disseminated isolated tumor cell has become a formidable object of solid tumor research for at least three good reasons: it can be identified in organ compartments such as bone marrow, blood, and lymph nodes and, once found, it can be morphologically characterized with respect to tumor-associated antigens, oncogenes, tumor suppressor genes, proliferation markers, and/or growth receptors. Thirdly, it is also an ideal target for immunotherapy directed at accessible, well-defined membrane-associated antigens of the tumor cell.