Residual tumor cell contamination in peripheral blood stem cells collections of 117 breast cancer patients evaluated by immunocytochemical technique.

During the last years, high-dose chemotherapy and hematopoietic stem cell support have been thought to improve the treatment of poor-prognosis breast cancer. Nevertheless, the question remained as to whether the reinfusion of contaminating residual malignant cells could contribute to relapse. By using an immunocytochemical method, we have analyzed the tumor cell contamination of peripheral blood stem cells (PBSC) collected from advanced breast cancer patients. We studied 153 PBSC samples from 117 stage III and IV breast cancer patients and compared two screening methods-the usual microscopic observation and the automated cellular image analysis system (ACIS-assisted) screening. With manual observation, we found that 7 of 117 patients (5.9%) presented circulating epithelial tumor cells in 9 of 153 (5.8%) PBSC analyzed, whereas automated screening allowed positive detection in 15 of the same 117 patients (12.8%) and in 18 of the 153 PBSC (11.7%). No difference was found between presence or absence of circulating tumor cells and previous chemotherapy treatment (p = 0.5) or stage TNM (p = 0.13) in this group of poor-prognosis breast cancer. We did not find incidence of infusion of contaminated PBSC on overall survival or time to progression.