Flow cytometric (DNA content and S-phase fraction) analysis of breast cancer.

The advent of therapeutic alternatives for patients with breast cancer has altered their clinical management profoundly. Because of this, the need for reliable prognostic indicators with definable clinical utility has spawned a number of objective evaluations of the neoplasm itself. Flow cytometric analysis of DNA and the cell cycle (S-phase fraction) are two of the objective measurements. Their current status in breast cancer is unclear. In the important category of carcinomas with negative axillary lymph nodes, DNA content (ploidy) information does not add important, independent, or prognostic information. S-phase fraction, in addition to correlating with DNA content and histologic grade, may be an independent factor, but methodologic variables have hampered definite conclusions about its utility. Currently, given the rather consistent absence of correlation between DNA ploidy, S-phase fractions, and nodal metastases, the independent prognostic utility of the two flow cytometric parameters can be questioned. A resolution of their final status in the prognostic hierarchy depends on rigorous adherence to the variables affecting them, i.e., preanalytic, analytic, and postanalytic factors.