The aim of the present study is to look at the mitotic activity index (MAI) as a prognostic factor in a prospective population-based cohort of lymph node-negative invasive breast cancer patients. Analyses were based on 2,048 breast-conserving therapies in 1,971 patients, node-negative, and without any form of adjuvant systemic therapy with long-term follow-up. The 15-year distant metastases-free survival (DMFS) for women B55 years was 88.3 % for low MAI values (B12) versus 73.4 % for high MAI values ([12); (HR 2.8; 95 % CI 1.8–4.4; p\0.001). Multivariate analyses for DMFS showed significance for MAI. For MAI and Bloom–Richardson grading, by performing a likelihood ratio test, we showed the statistical significance for both. For women[55-years, the MAI was not an independent significant factor. We also confirmed the above findings for disease-specific survival. When multi-gene assays are not available, the MAI remains a robust prognostic marker in women younger than 55 years of age with early node-negative breast cancer.
Jobsen, J. J., van der Palen, J. A. M., Brinkhuis, M., Nortier, J. W. R., & Struikmans, H. (2015). The prognostic relevance of the mitotic activity index in axillary lymph node-negative breast cancer. Breast cancer research and treatment, 149(2), 343-351. https://doi.org/10.1007/s10549-014-3244-8