Apoptosis induced by neoadjuvant chemotherapy in breast cancer

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Abstract
To evaluate the relationship between apoptosis induced by chemotherapy and clinical response in breast cancer. Apoptosis index (AI), mutant p53 and Bcl-2 protein expression were evaluated in 44 breast tumour samples from patients submitted to neoadjuvant chemotherapy. Objective response (OR) to primary chemotherapy was observed in 37 patients (84%) and no response (NR) in seven. AI was measured by the rate of apoptotic cells identified using morphological criteria. p53 and Bcl-2 protein expression were evaluated using an immunoperoxidase staining technique. The median AI change observed between prechemotherapy AI and post-chemotherapy AI was 0.84 in the OR group and 0.01 in the NR group, (rho=0.4; p=0.006). There was no change in Bcl-2 protein expression following chemotherapy. In the OR group, p53 protein expression was positive in 41.6% of patients before and in 22.2% after chemotherapy (difference = 16.6%; p=0.03). No change was detected in the NR group. A positive correlation was found between the increase in AI and clinical response to neoadjuvant chemotherapy in locally advanced breast cancer.