Micrometastases in non-small cell lung cancer (NSCLC).

Early metastasis is a well-known feature of poor prognosis in potentially resectable non-small cell lung cancer (NSCLC). However, a significant number of lymph node-negative patients die early of metastatic disease. Therefore, it has to be assumed that in some patients an early tumor cell dissemination has occurred which is clearly underestimated by current staging procedures. Recently, it has been shown, that an early dissemination of individual carcinoma cells to regional lymph nodes or bone marrow can be detected by using sensitive immunocytochemical techniques with monoclonal antibodies against epithelium-specific proteins. The incidence of immunohistochemically positive patients varies between 30 and 70% depending on the type of primary tumor, the immunohistochemical staining procedure used and especially on the primary monoclonal antibody. The detection of disseminated tumor cells in lymph nodes or bone marrow by immunocytochemistry is associated with a poorer prognosis in lung cancer. In conclusion, the immunohistochemical detection of disseminated tumor cells in lymph nodes can help to obtain a more exact identification of patients with an unfavorable prognosis. Whether the identified patients will gain from an adjuvant therapy, has to be evaluated in further studies.