Predictive value of flow cytometry for metastatic potential in breast cancer

Breast cancer is the leading malignancy in women in the United States. Tumor size and nodal metastases have been the most important predictors of patient outcome and determinants of treatment, but have also been used to predict metastatic potential. This study was undertaken to ascertain the predictive value of flow cytometry for lymph node or systemic metastases. From 1994 through 1997, surgical specimens from 106 women who underwent treatment for invasive breast cancer were reviewed. Epidemiological data, tumor stage, nodal metastases, and flow cytometric data were collected. Analysis of variance and Student's t test were used to determine whether the presence of nodal metastases or distant metastases correlated with high S phase values and aneuploidy. Of the 106 patients studied, the mean age was 57 years; tumor size consisted of 35 per cent T1, 48 per cent T2, 8 per cent T3, and 9 per cent T4. Node status was found in the following distribution: 56 per cent node negative, 38 per cent N1, and 6 per cent N2. Distant metastases were present in four patients. Elevated S phase (defined as >9.0%) was present in 72 per cent of the population. Fifty-six per cent of these tumors were aneuploid. Node-negative patients had an elevated S phase in 66 per cent of cases, whereas node-positive patients had an elevated S phase in 71 per cent of cases. Neither S phase (P = 0.91) nor DNA index (P = 0.99) proved to be statistically significant in determining axillary node status. Neither did S phase (P = 0.87) nor DNA index (P = 0.48) consistently predict the presence of distant metastases. There is no statistical correlation between axillary node status and flow cytometric data. Breast cancers with high S phase values and aneuploid features do not reliably have axillary nodal metastases, and this data cannot replace that information provided by axillary node dissection. Synchronous systemic metastatic disease is also not predicted by flow cytometry.