DNA flow cytometry and response to preoperative chemotherapy for primary breast cancer.

Between October 1988 and June 1990, 22 patients with locally advanced, inoperable breast cancer entered a pilot study of four cycles of anthracycline based cytotoxic chemotherapy followed by surgery and tamoxifen. Fine needle aspirate samples of tumour were obtained for DNA flow cytometry before treatment and during the first cycle of chemotherapy. 21 patients are eligible for assessment of response and toxicity. Chemotherapy was well tolerated with greater than WHO grade 2 vomiting or stomatitis in 4 patients. Granulocytopenia less than 10(9)/l was noted in 16/21 patients but there were no episodes of neutropenic sepsis. There were 7 complete responses (CR) and 11 partial responses (PR), giving an overall response rate to chemotherapy (CR+PR) of 18/21 (86%). Responses were observed more commonly in patients who had aneuploid tumours (P = 0.06) and in patients whose tumours had a high S-phase fraction (P = 0.1). Tumours which responded to chemotherapy (CR or PR) had a significantly higher median SPF compared with tumours which did not regress (P less than 0.05). There was no consistent pattern of change in SPF values during the first cycle of chemotherapy, either for patients who responded to treatment or for those whose tumours did not regress. This combination therapy is well tolerated with a high response rate. The results of this pilot study support the recent suggestion that tumours with rapidly proliferating, aneuploid populations of cells exhibit the best short-term response to chemotherapy.