The flow-cytometric analysis of DNA content and S-phase fraction (SPF) of human breast cancer.

The DNA ploidy of breast cancer tissue from paraffin blocks was measured by flow cytometry in 122 patients. In this material there was a difference in lymph node involvement and in the presence of distant metastases between diploid and aneuploid tumors. Diploid tumors were smaller than aneuploid tumors. Aneuploid tumors were more common in postmenopausal than in premenopausal women. Near tetraploid tumors were found in older patients rather than tumors with other ploidy patterns. The ploidy pattern was not associated with survival during the mean follow-up of 4.1 years. We specially studied the S-phase fraction (SPF) which was distinctly higher in aneuploid tumors than in diploid tumors. Also near tetraploid, hypertetraploid and multiploid tumors showed higher SPF than diploid tumors. The median of SPF in our material was 8.5%. Positive axillary lymph nodes were found in 32% of the patients who had tumors with an SPF below the median and in 46% of those with tumors above the median (SPF greater than 8.5%). The difference, however, was not statistically significant. In our material the SPF of the tumor did not show a significant association with survival. However, longer follow up time is needed for firm conclusions on the predictive value of cell DNA on survival.