Prognostic value of cytokeratin-positive bone marrow cells of gastric cancer patients

Background: Epithelial cells in the bone marrow of patients with gastric cancer suggest tumor dissemination; however, their prognostic implications are controversial. We prospectively evaluated the correlation of bone marrow findings, recurrence rate, and disease-free survival after long-term follow-up. Methods: Bone marrow were aspirated from both iliac crests and stained with monoclonal cytokeratin (CK)-18 antibody in 209 patients before their initial operation. Patients were followed up for a median of 56 months. Results: Overall, 39 (19%) of 209 patients and 15 (14%) of 109 R0-resected patients had CK-positive cells. CK-positive patients had more local, regional, and distant recurrence than CK-negative patients (P < .05). We found a significantly shorter disease-free survival (P < .05) in the patients with > 2 CK-positive cells per 2 x 10(6) bone marrow cells (mean, 35 months) than in patients with <= 2 CK-positive cells per 2 x 10(6) bone marrow cells (mean, 70 months) or in patients with no CK-positive cells (mean, 86 months). Multivariate analysis confirmed that > 2 CK-positive cells per 2 x 10(6) bone marrow cells was an independent prognostic factor for tumor-related death (P < .05). Conclusions: Not only the mere presence of CK-positive epithelial cells in bone marrow, but also the cell number, correlates with prognosis. Our findings suggest that classifying CK-positive bone marrow cells in these patients will facilitate future studies.