Abstract: ObjectiveTo investigate the effect of neoadjuvant chemotherapy on the proportion of G0G1 phase cells and the expressions of ATPbinding cassette subfamily G member 2 (ABCG2) and CD44＋CD24-/low in breast cancer patients. MethodsSixty untreated cases with breast invasive ductal carcinoma from May 2013 to March 2014 were chosen. All patients were tested by core needle biopsy and pathological diagnosis, then treated by neoadjuvant chemotherapy. The proportion of G0G1 phase cells and the contents of ABCG2 and CD44＋CD24-/low before and after therapy were compared. ResultsAfter chemotherapy, the contents of ABCG2 and CD44＋CD24-/low were (25.10±1.50)% and (36.40±3.80)/105, and the proportion of G0G1 phase cells was  (70.50±1.50)%, which were higher than those before treatment ［(15.88±1.22)%, (25.00±3.40)/105, (60.65±1.30)%］ (t=8.685, P＜0.05; t=9.226, P＜0.05; t=8.898, P＜0.05). All patients completed four courses of chemotherapy, and the cCR rate, cPR rate, SD rate were respectively 18.3% (11/60), 73.3% (44/60), 8.3%(5/60). ConclusionCell cycle can be arrested and the proportion of stem cells can be raised after neoadjuvant chemotherapy which has exact curative effect and clinical popularization value.

Key words: Breast neoplasms, Cell cycle, Stem cells