Bone marrow micrometastases in breast cancer patients

The presence of epithelial cells in bone marrow may be a prognostic factor in breast cancer, and so we evaluated their evolution in treated and untrea ted patients. A first bone marrow aspirate was obtained from 125 stage I/II breast cancer patients at diagnosis and repeated every 6-8 months; the sam ples were processed for leukocyte separation, used to prepare cytospin slid es, stained with a pool of monoclonal antibodies (MoAb) recognising epithel ial antigens, and immunocytochemically processed. The median follow-up was 48 months (range 15-82); 23 patients relapsed, and 14 died. MoAb positive c ells were observed in 31.2% of first, 24.3% of second, and 27.8% of third a spirates. In 68/100 pairs of successive aspirates, bone marrow status remai ned unchanged; in 20 it became negative, and in 12 positive (not statistica lly significant even after adjusting for adjuvant therapy). An analysis bas ed on Mantel and Byar's approach to time-dependent covariates using all 225 aspirates found no statistically significant prognostic difference between the patients with negative and positive bone marrow. Bone marrow status ch anged over time in about 1/3 of the patients; adjuvant therapy did not affe ct the probability of its becoming negative or positive. No significant ass ociation was found between bone marrow evolution and relapse or death, but the relatively high probability of a change in status over time cannot excl ude the possibility that a positive aspirate during the course of breast ca ncer may be a negative prognostic factor.