Monoclonal antibodies in the detection of bone marrow metastases in small cell lung cancer.

Using conventional examination (CE) of H&E stained slides from bone marrow aspirates, metastases can be detected in approximately 25% of patients with small cell lung cancer. We investigated a panel of monoclonal antibodies using immunohistochemistry in the diagnosis of bone marrow infiltration from SCLC and compared the results with CE. Seven monoclonal antibodies raised against epithelial antigens (CAM 5.2, MOV 15, NCCST 433, PE 35, LCA1/L38, HMFG 1 AND HMFG 2) were applied on bone marrow sections from three groups of patients (pts): (1) 19 pts in whom SCLC-metastases were detected by CE, (2) 44 pts with SCLC in whom metastases could not be detected by CE, and (3) 20 pts with non-malignant bone marrow diseases. All the antibodies except LCA1/L38 were positive in 60-90% of the slides with infiltrating tumour cells in group 1. No positive tumour cells were detected in group 2. A few plasma cells and megakaryocytes were slightly positive for MOV 15 and NCCST 433, but no other positive cells were detected in group 3. In conclusion, the monoclonal antibodies used in this study may be useful for diagnostic purposes when a suspicious looking infiltration is detected by CE. However, these antibodies could not detect metastatic tumour cells in the bone marrow sections from patients in whom CE did not reveal any tumour cells.