DNA ploidy and other results of DNA flow cytometry as prognostic factors in operable breast cancer: 10 year results of a randomised study.

We evaluated breast cancer specimens from 241 patients of a controlled clinical trial by means of DNA flow cytometry. We report the correlations between DNA index (DNI) and fraction of cells in S-phase (SPF) and other prognostic parameters. Both univariately and in a Cox model, the predictive power of these factors is evaluated after a follow-up of more than 10 years. There are strong correlations between DNI and SPF (P = 0.0001) and between flow cytometry parameters and clinical and histopathological factors such as axillary lymph node involvement, tumour size and histological grade. In univariate analysis DNI fails to provide prognostic information, whereas SPF turns out to be able to differentiate between patients at high and low risk for relapse and death (P = 0.002). In the multivariate Cox model, too, SPF is an important prognostic parameter with respect to patient survival (relative risk: +86%), only surpassed by nodal involvement. DNI, however, turns out to be an independent predictor of relapse free survival and distant recurrence free survival. By combination of DNI and SPF, patients can be divided into three prognostic subgroups. We conclude that data from DNA flow cytometry can be of great importance for the decision on the level of aggressiveness of adjuvant therapy for an individual patient and therefore may help to avoid overtreatment and toxicity.