Analysis of the cytogenetic response in peripheral blood lymphocytes from breast cancer patients following chemotherapy.

The presence of chromosomal aberrations induced in circulating lymphocytes from breast cancer patients during chemotherapy was analyzed. Ten breast cancer patients undergoing neoadjuvant chemotherapy and ten healthy women (controls) were evaluated. Metaphases were obtained from cultures of peripheral lymphocytes stimulated with phytohemaglutinin and metaphase blockage was achieved with colchicine. One hundred metaphases were analyzed for chromosomal aberrations and 1,000 cells for the mitotic index. No significant differences were observed regarding the frequency of chromosomal aberrations, number of cells with chromosomal aberrations and mitotic index between the controls and patients before chemotherapy. However, after the first chemotherapy cycle, the numbers of chromosomal aberrations and cells with them was greater. After the third cycle, the mitotic index was lower, but the fifth cycle produced an increase in relation to the third and fourth cycles. The results suggest that chemotherapy raises the number of chromosomal aberrations and favors persistence of stable chromosomal abnormalities.