DNA ploidy and the percentage of cells in S-phase as prognostic factors for women with lymph node negative breast cancer

Abstract

Previous cell kinetic studies have shown that the percentage of cells in S-phase (%S) of the tumor may be an important prognostic factor for relapse-free survival (RFS) and overall survival (OS) in patients with resected lymph node negative breast cancer. This study examined DNA ploidy and %S from the paraffin embedded primary tumors of 265 patients who had surgery between 1975 and 1981, had lymph node negative cancer, and had no adjuvant therapy. The %S and %G2M values were calculated using a debris and aggregate subtraction model. The results of the DNA ploidy analysis revealed 130 (49%) DNA diploid tumors and 135 (51%) DNA nondiploid tumors. Ploidy was not significant for either RFS (P = 0.20) or OS (P = 0.13). The total %S (using a cutoff of 8%) was a statistically significant prognostic factor for RFS (P = 0.003) and borderline for OS (P = 0.08). The proliferation fraction (%S + %G2M), using a cutoff of 12.5, was a statistically significant prognostic factor for RFS (P = 0.01) and for OS (P = 0.01). In a Cox multivariate analysis for RFS, the total %S remained significant (P = 0.05) along with tumor size. In the analysis of OS, the proliferation fraction remained significant (P = 0.03) along with tumor size and age. DNA ploidy was not significant in any multivariate analysis. This study suggests that tumor size and cell proliferation parameters are independent prognostic factors for patients with resected lymph node negative breast cancer. However, the clinical usefulness of the cell kinetic parameters appears limited.