Detection of occult micrometastases in bone marrow of patients with breast cancer

Immunohistochemical examination of bone marrow of four patients with invasive ductal breast adenocarcinoma was performed in order to find extrinsic carcinoma cells. They were found in 3 of 4 patients and the reliability of the procedure was evaluated in comparison with a control group of women. It consisted of 4 haematologically ill patients who underwent bone marrow aspiration for routine diagnosis and gave consent to use part of their sample. The detection of occult micrometastases turned to be a very important prognostic factor because the bone marrow can be infiltrated by extrinsic carcinoma cells even in the absence of occult micrometastases in lymph nodes. Two monoclonal antibodies were used, MNF116 against submembranous cytokeratins which belong to the group of intermediate filaments, and HMFG-2 against human milk fat globule antigens localized on cell surface. Both were sensitive enough to detect small clusters of carcinoma-derived cells in thf bone marrow. As the test with haematologically ill patients revealed nonspecific or background false positivity was not encountered. Regarding the importance of early prediction of the recurrence of disease, we recommend this examination on the first clinical presentation and without overt evidence of metastatic spread.