Prognostic significance of DNA-ploidy in a series of 690 primary breast cancer patients

Abstract

Flow cytometric DNA-ploidy measurements were performed on paraffin-embedded and fresh tumor specimens from 690 patients with Stage I-III breast cancer. The conventional classification of DNA-ploidy (diploid versus aneuploid) was compared with a division of tumor ploidy into 5 classes based on DNA index (DI) range. The DI-classification showed a better correlation with tumor size and TNM stage than the conventional classification. Aneuploidy was associated with an impaired survival and distant relapse-free survival (p = 0.02) but the DI-classification improved the discrimination between different prognostic groups of patients. In general, this indicated a more aggressive phenotype for tumors evolved via polyploidization. Hyper-tetraploidy (DI greater than 2.10) indicated a very poor prognosis in pre-menopausal patients. No prognostic effect of aneuploidy and DI-class was found in node-negative and TI patients. Cox multivariate regression analysis showed that aneuploidy was an additional prognostic factor to nodal status (I less than or equal to N less than or equal to 3, N greater than 3 vs. N = 0) and tumor size (T2-4 vs. TI) for overall and distant relapse-free survival. Subdivision according to DI-class did not improve the prognostic power of DNA-ploidy due to stronger correlations with established prognostic factors.