Immunologic Proliferation Marker Ki-S2 as Prognostic Indicator for Lymph Node-NegativeBreast Cancer

• Published in: JNCI : Journal of the National Cancer Institute 1999-02, Vol.91 (3), p.271-278
• Main Authors: Rudolph, Pierre, Alm, Per, Heidebrecht, Hans-Jürgen, Bolte, Hendrik, Ratjen, Virgo, Baldetorp, Bo, Fernö, Mårten, Olsson, Håkan, Parwaresch, Reza
• Format: Article
• Language: English
• ISSN: 0027-8874; 1460-2105
• DOI: 10.1093/jnci/91.3.271

BACKGROUND: Proper treatment of lymph node-negative breast cancer depends on an accurate prognosis. To improve prognostic models for this disease, we evaluated whether an immunohistochemical marker for proliferating cells, Ki-S2 (a monoclonal antibody that binds to a 100-kd nuclear protein expressed in S, G2, and M phases of the cell cycle), is an accurate indicator of prognosis. METHODS: We studied 371 Swedish women with lymph node-negative breast cancer; the median follow-up time was 95 months. The fraction of tumor cells in S phase was assessed by flow cytometry, and tumor cell proliferation was measured immunohistochemically with the monoclonal antibodies Ki-S2 and Ki-S5 (directed against the nuclear antigen Ki-67). A combined prognostic index was calculated on the basis of the S-phase fraction, progesterone receptor content, and tumor size. RESULTS: In multivariate analyses that did or did not (263 and 332 observations, respectively) include the S-phase fraction and the combined prognostic index, the Ki-S2 labeling index (percentage of antibody-stained tumor cell nuclei) emerged as the most statistically significant predictor of overall survival, disease-specific survival, and disease-free survival (all two-sided P