Effect of neoadjuvant chemotherapy on Ki67 labelling index, c-erbB-2 expression and steroid hormone receptor status in human breast tumours.

The administration of neoadjuvant chemotherapy to breast cancer (BC) patients with operable disease allowed studies aimed of exploring the interaction between cytotoxic treatment and tumour biology in vivo. 99 patients with T2-4, NO-1, M0 primary BC received a median of 3 cycles of either CMF regimen (cyclophosphamide, methotrexate, 5-fluorouracil) or single agent epirubicin. Endocrine therapy was also concomitantly administered in the first 45 patients with estrogen receptor positive (ER+) BC. 92 ended the treatment plan. Ki67 labelling index, estrogen receptor (ER), progesterone receptor (PgR), and c-erbB-2 oncoprotein expression were evaluated immunohistochemically in tumour biopsies obtained before and after chemotherapy. At post-chemotherapy evaluation, tumour shrinkage greater than 50% was obtained in 71 patients (79.7%), 27 of them being complete responders (30.3%). The median Ki67 labelling index, which was 13% in the first biopsy, decreased to 4.5% (p < 0.001) upon mastectomy. No significant differences were observed in steroid hormone receptor and c-erbB-2 expression before and after neoadjuvant treatment. In conclusion, neoadjuvant chemotherapy, whether associated or not to endocrine therapy, leads to a significant decrease in BC proliferation without any appreciable impact on c-erbB-2 and steroid hormone receptor expression.