Prediction of relapse or survival in patients with node-negative breast cancer by DNA flow cytometry

More accurate prediction of the prognosis in women with node-negative breast cancer may improve physicians' ability to identify the patients most likely to benefit from systematic adjuvant therapy. With this in mind, we performed DNA flow-cytometric measurements of ploidy and the fraction of cells in the synthesis phase of the cell cycle (S-phase fraction) on 395 specimens of node-negative breast cancer from our bank of frozen tumors, using the aliquots of pulverized frozen tissue from steroid-receptor assays. The median duration of follow-up in patients still alive at the time of analysis was 59 months. Thirty-two percent of the 345 specimens that could be evaluated were diploid, and 68 percent were aneuploid. The probability of disease-free survival at five years was 88 +/- 3 percent in patients with diploid tumors and 74 +/- 3 percent in those with aneuploid tumors (P = 0.02). The S-phase fraction was not a significant additional predictor of disease-free survival in patients with aneuploid tumors. However, the probability of disease-free survival in patients with diploid tumors and low S-phase fractions was 90 +/- 3 percent at five years, as compared with 70 +/- 13 percent in those with diploid tumors and high S-phase fractions (P = 0.007). Similar differences in overall survival were noted. We conclude that DNA flow-cytometric measurements of ploidy and S-phase fraction can be performed on frozen specimens of tumors and are potentially important predictors of disease-free and overall survival in patients with node-negative breast cancer.