Minimal residual disease in non-small-cell lung cancer.

Early metastatic relapse after complete resection (R0) of apparently localized primary tumors is frequent in patients with non-small-cell lung cancer (NSCLC). This observation indicates an occult tumor cell dissemination already present at the time of primary surgery but undetectable by current tumor staging methods. During the past 10 years ultrasensitive immunohisto-/-cytochemical and molecular assays have been developed that are able to detect single tumor cells and small tumor cell clusters present in lymph nodes classified as tumor-free by conventional histopathologic analysis, bone marrow, or peripheral blood. Here we present an overview of the incidence and prognostic impact of such early disseminated tumor cells in patients with NSCLC.