Immunohistochemical detection of tumor cells in the bone marrow of breast cancer patients

BACKGROUND: Contamination of bone marrow and peripheral blood stem cells with tumor cells is a problem that may be encountered when autologous hematopoietic stem cell transplantation is conducted concurrently with high-dose chemotherapy. METHODS: Using monoclonal antibodies to a variety of tumors, the detection of tumor cells in the bone marrow of breast cancer patients was studied by immunohistochemistry. RESULTS: KL-1 and CAM5.2 were strongly reactive with breast cancer cells, but not with normal bone marrow cells. The reactivity of the tumor cells with EMA was not strong, and DF-3 and 115D8 yielded only slightly positive reactions. These latter antibodies also exhibited some reactivity to normal bone marrow cells. When tumor cells were admixed with normal cells, the sensitivity of CAM5.2 and EMA permitted the detection of one cell in 10(4), but with KL-1, the detection of one in 10(5) cells was possible. When immunohistochemical staining was used in testing 40 patients with advanced or recurrent breast cancer, positive reactions were obtained in four of 27 patients (14.8%) with KL-1, four of 26 (15.4%) with CAM5.2, and nine of 37 (23.7%) with KL-1 + CAM5.2, figures similar to those reported by others who studied stage IV patients. CONCLUSIONS: Immunohistochemical staining with KL-1 and CAM5.2 is therefore considered to be a useful technique for detecting contamination by tumor cells.