Phagocytic tumor cell activity in oat cell carcinoma of the lung

Biopsy specimens from 14 patients with oat cell carcinoma of the lung metastatic to bone marrow and from one patient with a localized tumor were examined for evidence of phagocytic activity by tumor cells. Phagocytic activity was observed in tumor cells in 90 per cent of the bone marrow biopsy specimens, 90 per cent of the cytology specimens, and 70 per cent of the biopsy specimens of other tissues. The cell most often phagocytosed was the leukocyte. Seventeen other tumors metastatic to bone marrow were studied and only one evidenced phagocytic activity.