DETECTION OF GENETIC ALTERATIONS IN MICROMETASTATIC CELLS IN BONE-MARROW OF CANCER-PATIENTS BY FLUORESCENCE IN-SITU HYBRIDIZATION

Detection of micrometastatic tumor cells in bone marrow of cancer pati ents has been shown to be of prognostic significance. To further chara cterize these cells, we combined antibody labeling and fluorescence in situ hybridization (FISH). For detection of numerical changes of chro mosome 17, nine patients with proven breast cancer whose bone marrow c ontained epithelial tumor cells were evaluated. Epithelial cells were stained by anticytokeratin antibody. Afterwards FISH was performed usi ng an ct-satellite probe specific for chromosome 17. In a second serie s bone marrow epithelial cells of eight patients with breast cancer an d of six with prostatic cancer were evaluated for the amplification of HER-2/neu by using a gene-specific DNA probe. In the first series fou r patients had only single epithelial cells in their bone marrow. Only one single cell showed five hybridization signals, whereas all other single cells showed two or less. Five patients had clusters of epithel ial cells in bone marrow with or without additional single cells. One hundred four cells had three or more hybridization signals and 103 of these polysomic cells were located in tumor cell clusters. In the seco nd series we could detect HER-2/neu amplification in bone marrow epith elial tumor cells in two of eight patients with breast cancer but in n one of the prostatic cancer patients. These results show that if is po ssible to detect numerical chromosomal changes and oncogene amplificat ion in bone marrow micrometastatic epithelial cells of cancer patients by combining immunophenotyping and FISH.