Micrometastatic tumor cells in the bone marrow of patients with non-small cell lung cancer

Background. This study was designed to evaluate the incidence and clinical implications of detection of micrometastatic cancer cells in bone marrow aspirates of patients with operable non-small cell lung cancer. The relationship between micrometastatic cells and p53 overexpression in the primary tumor was also assessed. Methods. Thirty-nine patients with stages I through III non-small cell lung cancer who underwent curative resection were entered into this study. Immunohistochemistry with monoclonal antibody to cytokeratin 18 was used to detect tumor cells in bone marrow. Immunostaining of p53 protein in the corresponding primary tumors was also done. Results. Cytokeratin 18-positive cells were detected in 15 (39%) of the 39 patients. Overexpression of p53 was associated with positivity of the tumor cells in the bone marrow at borderline significance (14/29 versus 1/10; p = 0.0574). The patients with cytokeratin 18-positive cells in bone marrow demonstrated a significantly earlier recurrence than those without such cells (p = 0.0083, log-rank test). Conclusions. Micrometastatic cancer cells were frequently present in bone marrow of patients with operable non-small cell lung cancer and may be a significant predictor of early recurrence. Further evaluation of this method may be useful in identifying patients with nonsmall cell lung cancer who are most likely to benefit from adjuvant chemotherapy.