Prognostic significance of DNA ploidy determined by high-resolution flow cytometry in breast carcinoma

OBJECTIVE: To assess the prognostic value of DNA ploidy in breast carcinoma and its relation to other established prognostic factors. STUDY DESIGN: We evaluated DNA ploidy in 303 breast carcinoma patients with a median follow-up of 63 months. Flow cytometry was performed on frozen tumor material, yielding histograms with narrow peaks (median coefficient of variation of 2.08). DNA ploidy pattern was classified as either diploid versus nondiploid, euploid (diploid and tetraploid) versus aneuploid or diploid/near-diploid (DNA index < 1.2) versus other, and correlated with relapse-free (RFS) and cancer-specific survival (CSS) along with tumor size, histologic grade and type, axillary lymph node involvement, menopausal and steroid receptor status, age and type of treatment. RESULTS: Seventy-one percent of tumors were DNA nondiploid (14% tetraploid and 57% aneuploid). There was a strong association between DNA ploidy and histologic grade. Histologic grade, lymph node status, tumor size and DNA ploidy (regardless of the classification used) were all significantly associated with RFS and CSS in multivariate analysis. CONCLUSION: These results suggest that DNA ploidy, at least when determined from frozen tumor tissue, is an independent prognostic factor in breast carcinoma; however, its prognostic power seems to be inferior to that of histologic grade, with which it strongly correlates.