Comparison of cell growth in different parts of breast cancers

This study was performed to answer the question: which parts of breast cancers are active in terms of proliferation as measured by the Ki‐67 antibody and in terms of cell division as measured by the mitotic index. Forty‐six breast samples were studied, including 34 breast cancers and 12 benign conditions. The intraductal component of infiltrating breast cancers showed a significantly lower proliferation index than the infiltrating component. The cells at the periphery of infiltrating tumour strands showed a higher proliferation activity than the cells in the core. These findings suggest that infiltration advances through preferential active growth of the cells at the invasion front.