DNA flow cytometry and pathologic grading as prognostic guides in axillary lymph node-negative breast cancer

The recurrence or mortality rate of axillary lymph node-negative invasive breast cancer has been associated with the tumor S-phase fraction, which is measured by DNA flow cytometry. Because many of the studies that established this association were performed using frozen, pulverized tumor specimens, this association could not be tested for independence from the established prognostic factors of histologic and nuclear grading.

Histologic, nuclear, and mitotic grades, DNA ploidy, and S-phase fraction (SPF) were determined from paraffin-embedded tumors obtained from 280 women with node-negative invasive ductal carcinomas using standard grading schemes and flow cytometric techniques. These variables were compared with disease-free and cancer-specific survival (CSS) in univariate and multivariate analyses of these patients.

Tumor diameter, SPF, histologic grade, and nuclear grade were significant predictors of disease-free survival (DFS); diameter and SPF had significant associations with CSS. Cox analysis showed histologic grade to be the only independent predictor of relapse, whereas diameter and SPF were independent predictors of mortality. The patients with low nuclear or histologic grade tumors had only a 5% risk of recurrence at 5 years. In contrast, 36% of patients in this series with medium-grade or high-grade high SPF tumors had a 30% risk of recurrence over the same interval.

Histopathologic grading and flow cytometric determination of SPF appear to provide additive prognostic information for patients with early invasive ductal carcinomas of the breast.