Cell cycle modifications of breast cancers during neoadjuvant chemotherapy: a flow cytometry study on fine needle aspirates.

Breast cancer cells from 92 patients were obtained by repeated fine needle sampling and analysed by flow cytometry for cell cycle modifications during neoadjuvant chemotherapy. Modifications of the histograms were observed for 47 of the 71 informative cases (66%), the most frequent concerning S-phase (increase or decrease) and G2M accumulation. These modifications correlated well with the efficacy of cytotoxic chemotherapy (P < 0.0001). A significant relationship between clinical regression and pretreatment proliferative activity was also observed, with 31/35 (89%) responders in the high proliferation group (S-phase fraction > 5% or BrdU labelling index > 3.3%) compared to 20/36 (56%) in the low proliferation group (P < 0.002). For patients undergoing chemotherapy including doxorubicin, a high incidence of G2M accumulation was observed (33%), a modification which was rare (4.5%) for a regimen with no anthracycline, for which S-phase was the most frequently modified cell cycle compartment (64%). The measurement of the pretreatment tumour proliferative activity as well as the early kinetic modifications, as indicators of response, may prove interesting parameters for the future management of neoadjuvant chemotherapy.