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 tu mor material, yielding histograms with narrow peaks (median coefficient of variation of 2.08). DNA ploidy pattern was classified as either diploid ver sus nondiploid, euploid (diploid and tetraploid) versus aneuploid or diploi d/near-diploid (DNA index < 1.2) versus other, and correlated with relapse- free (RFS) and cancer-specific survival (CSS) along with tumor size, histol ogic grade and type, axillary lymph node involvement, menopausal and steroi d 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 h istologic grade. Histologic grade, lymph node status, tumor size and DNA pl oidy (regardless of the classification used) were all significantly associa ted 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 ca rcinoma; however, its prognostic power seems to be inferior to that of hist ologic grade, with which it strongly correlates.