The study analyzes the prognostic implication of cell kinetics on 52 locally advanced breast cancers. All patients were subjected to a multimodal treatment, including primary chemotherapy with doxorubicin and vincristine, surgery, or radiotherapy followed by additional chemotherapy with the same drug regimen. Pretreatment labeling index (LI) is not related to response to primary chemotherapy, whereas it provides information on the course of the disease. In fact, high LI significantly predicts a higher progression rate at the end of the entire combined treatment, a shorter time to disease progression, and a poorer probability of 4-year survival in comparison to low LI. From the present findings, LI appears to be a useful tool to select women with locally advanced breast cancer that would require very aggressive treatment.