MIB-1 PROLIFERATIVE ACTIVITY IN INVASIVE BREAST-CANCER MEASURED BY IMAGE-ANALYSIS

Aims-To determine cell, proliferation in infiltrating breast carcinoma s. Methods-Using the MIB-1 monoclonal antibody, the proliferation inde x was measured in paraffin wax sections of 871 breast cancers. The MIB -1 proliferation index was compared with other markers of disease prog ression: size, lymph node status, histotype, oestrogen and progesteron e receptor status, expression of p53 and Neu, and DNA ploidy. All para meters were measured using image analysis. In 347 tumours, the MIB-1 a nd Ki-67 proliferation indexes were compared. Follow up data were avai lable for 170 cases (median 66.5 months). Results-Of the tumours, 314 (36%) had a high proliferation index. The MIB-1 proliferation index wa s correlated directly with size, nodal status, overexpression of p53 a nd Neu, and the DNA index; and inversely with oestrogen and progestero ne receptor status. The correlation between MIB-1 and Ki-67 proliferat ion indexes was statistically significant. In patients with pT1 tumour s, a low proliferation index correlated with a longer relapse-free int erval and overall survival; node negative patients with a low prolifer ation index had a longer overall survival. Conclusions-The MIB-1 proli feration index is a reliable, practical and useful method of measuring proliferative activity and is an important predictor of clinical beha viour.