DNA analysis in advanced breast cancer.

DNA flow cytometry is frequently used to determine the aggressiveness of breast cancer at the time of primary treatment. Because its role is not as clear in advanced disease, a retrospective investigation was conducted on 132 breast cancer patients with metastases or a subsequent recurrence of the disease. DNA analysis of 96 primary tumors and 53 metastases was performed. The follow-up time was up to 11 years. The mean DNA index of the primary tumors was 1.4 and the mean S-phase fraction (SPF) was 9.4%; 36.5% of the tumors was diploid. The DNA index did not differ significantly among the different stages, but the SPF was significantly higher in stage III than in stage IV. There was no significant difference in ploidy between the stages. There were no significant differences in DNA index and SPF between the primary tumors of the patients with local or distant metastases. The disease-free interval was independent of DNA index, ploidy, and SPF alone. There was no difference in DNA index, ploidy, or SPF between patients with an early or late relapse. Breast cancer-related mortality after metastasis was independent of ploidy alone. In stage I-II, patients with a low SPF had a significantly higher survival rate than other patients. The same was true in patients with a diploid tumor and a low SPF. When the DNA index, SPF, and ploidy of primary tumors and metastases/recurrences were analyzed, no combination of variables yielding an improved prognosis was found. Therefore, it seems that DNA flow cytometry has limited value in determining the prognosis in a patient with metastases or recurrence.