The value of S-phase and DNA ploidy analysis as prognostic markers for node-negative breast cancer in the Australian setting.

This study aimed to determine the prognostic significance of DNA ploidy and S-phase fraction (SPF) measurements in our laboratory for patients with node-negative breast cancer. Frozen tumors from axillary node-negative breast cancer patients (n = 50) treated at Westmead Hospital, NSW, between 1988 and 1991 were analysed by flow cytometry. The median duration of follow-up for all patients was 8.4 years. Forty-six specimens provided evaluable DNA histograms with 43% (n = 20) diploid and 56% (n = 26) aneuploid tumors identified. Comparisons of DNA ploidy status and SPF were made with traditional prognostic variables, which included age, menopausal status, tumor size, histologic grade and hormone receptor status. Our results showed that there was no significant difference in disease-free or overall survival between patients with diploid and aneuploid tumors. Histologic grade 3 tumors were more likely to be aneuploid and had higher SPF than grade 1 or 2 tumors. Patients with grade 3 tumors and a high SPF were four times more likely to relapse than the rest of the population. These results indicate that DNA flow cytometric analysis in our laboratory provides additional prognostic data that could be utilised alongside traditional clinical and histopathologic indicators for predicting outcome for patients.