Multivariate prognostic evaluation of the mitotic activity index and fibrotic focus in node-negative invasive breast cancers

We validated with univariate and multivariate (Cox) analysis, the prognostic value of the mitotic activity index (MAI), the fibrotic focus (FF) and other prognosticators in 448 patients with lymph node-negative (LN-) invasive breast cancer 1/3 of the tumour area, had distant metastasis rates of 17%, 35% and 48%; in MAI <10 and FF absent, FF <1/3 or FF > 1/3, metastasis rates were 11%, 13% and 42% and if MAI ≥ 10, metastasis rates were 31%, 48% and 50%, respectively. In the 12 patients with MAI <10 and a large FF > 1/3, event-free survival was similar to patients with MAI ≥ 10. With multiple regression MAI <10 versus ≥10 is the strongest prognosticator (also stronger than the SG). The FF may be important as it has additional prognostic value to the MAI in the small subgroup of invasive ductal or mixed-ductal breast cancer patients with combined MAI <10 and an FF > 1/3 of the tumour area.