Clinical significance of cytokeratin positive cells in bone marrow of gastric cancer patients.

Bone marrow (BM) is a prognostically relevant indicator organ of micrometastasis; however, the clinical importance of BM micrometastasis in gastric cancer patients is not yet known. In the present study, the BM of 267 consecutive patients with primary gastric cancer was examined for tumor cells using immunocytochemical techniques. Real-time quantitative RT-PCR was used to ensure that the tumor cells were detected properly. Among the 267 cases analyzed, 30 cases (11.2%) had cytokeratin-positive cells in the bone marrow. Positive findings were related to the tumor stage (P<0.05) and to the prominent depth of invasion (P<0.05). All patients with liver metastasis at operation had cytokeratin-positive cells in the BM. Recurrence of the disease was confirmed in 50 cases (18.7%); 4 of 30 (13.3%) in the cytokeratin-positive group and 46 of 237 (19.4%) in the cytokeratin-negative group. There were no significant differences in the 5-year survival rates between the cytokeratin-positive and cytokeratin-negative groups. Our study shows that BM micrometastasis increases according to tumor progression; however, only a subset of cancer cells may survive in the BM and finally evolve to a clinically apparent disease. Therefore it does not accurately predict the prognosis or recurrence of the disease.