Objective: To investigate whether the S + G2/M fraction (proliferative index) is a prognostic determinant in breast cancers classified as Auer IV.
Study design: Prognostic evaluation of Auer IV DNA histograms with respect to the high versus low S + G2/M fraction, obtained by image cytometry on consecutive breast cancer imprint preparations.
Results: When studying recurrence-free survival (n = 136), the prognostic value of S + G2/M was found to vary with time: it was negligible before the median time to relapse (1.5 years) but thereafter statistically significant, in both univariate and multivariate analysis. The same pattern was found when overall survival was used as the end point; the effect was delayed to about the median time until death (three years). Tumors with a low S + G2/M fraction were smaller and more often estrogen receptor- and progesterone receptor-positive than those with a high S + G2/M fraction.
Conclusion: According to ICM-DNA values corresponding to the S + G2/M region, patients with breast cancers classified as Auer IV can be divided into subgroups with different tumor characteristics and prognoses.