Molecular and immunological detection of circulating tumor cells and micrometastases from solid tumors

Histological, immunological, and molecular methods have been used for detecting micrometastases from nonhematopoietic malignancies. Early studies utilizing cytological methods to identify circulating tumor cells demonstrated the uncertain significance of micrometastasis detection for predicting eventual recurrent disease. Recently, reverse transcriptase-polymerase chain reaction (RT-PCR) for the detection of circulating tumor cells has been suggested as a potential technique for staging of cancer. Studies using RT-PCR thus far indicate that test results may be negative in some patients with known metastatic disease, thereby raising doubts about the utility of the method for staging of disease. In this review, we survey the relevant literature and discuss the range of current applications of histological, immunological, and molecular methods for detecting micrometastases from solid tumors in blood, bone marrow, and lymph nodes and the progress toward determining the significance of micrometastasis detection.