Primary chemotherapy in locally advanced breast cancer (LABC): effects on tumour proliferative activity, bcl-2 expression and the relationship between tumour regression and biological markers.

The rate of tumour cell proliferation evaluated by the [3H]-thymidine labelling index ([3H]-dT-LI) is known to be an independent prognostic factor in patients with operable breast cancer and significantly predicts the response to chemotherapy in patients with advanced disease. In locally advanced breast cancer (LABG), we examined whether chemotherapy induced modifications in [3H]-dt-LI, and bcl-2 expression and their relationship with tumour regression and prognosis. 70 LABC patients received three courses of primary chemotherapy (FEC: 5-fluorouracil 600 mg/m2, epidoxorubicin 60 mg/m2, cyclophosphamide 600 mg/m2, followed by surgery and subsequent adjuvant chemotherapy consisting of three courses of FEC alternated with three courses of CMF (cyclophosphamide 600 mg/m2, methotrexate 40 mg/m2, 5-fluorouracil 600 mg/m2). Tumour biological markers were evaluated on diagnostic biopsy, before primary chemotherapy and at surgery. Tumour cell proliferation was determined by [3H]-dT-LI, whilst bcl-2 expression was examined by immunohistochemical staining. The overall response rate to primary FEC was 74.3% (95% confidence interval 57.6-83.2%). The response rate correlated with high [3H]-dT-LI: 88% (29/33) of patients with high [3H]-dT-LI achieved an objective response compared with 62% (23/37) of patients with low [3H]-dT-LI (P = 0.014). The 3 patients achieving a pathological complete response after induction treatment had high proliferative tumours. The highest 2-year relapse free survival (66.6%) was observed in patients with low [3H]-dT-LI after primary chemotherapy. The median bcl-2 expression values before and after primary chemotherapy were 0% (range 0-80) and 30% (range 0-90), respectively (P = 0.03). Our data indicate that primary chemotherapy can modulate tumour cell kinetics and apoptosis-related genes. Pretreatment proliferative activity correlated with tumour response, whilst post-treatment [3H]-dT-LI correlated with relapse free survival.