Proliferation accurately identifies the high-risk patients among small, low-grade, lymph node-negative invasive breast cancers

Background: The proliferation factor mitotic activity index (MAI) is the strongest prognosticator in lymph node-negative invasive breast cancer patients under age 71. The question remains, whether this also holds for ‘favourable prognosis’ subgroups. Patients and methods: The study was a multicentre prospective analysis of the MAI for recurrence-free survival and overall cancer-related survival of grade, MAI, and other prognosticators in 853 long-term follow-up, T1–3N0M0 breast cancer patients under 71 years. Results: In all tumours together (N = 853), in grade 3 (n = 269), in tumours