Conventional versus cytokinetic polychemotherapy with estrogenic recruitment in metastatic breast cancer: results of a randomized cooperative trial.

Diethylstilbestrol (DES) can induce a recruitment into the proliferative pool of previously resting breast cancer cells in vivo. In order to verify if estrogenic recruitment could result in a larger tumor cell killing by chemotherapy, 117 patients with metastatic breast cancer were randomized to receive CEF (cyclophosphamide, 600 mg/m2; epidoxorubicin, 60 mg/m2; and 5-fluorouracil, 600 mg/m2 on day 1); DES-CEF (cyclophosphamide, 600 mg/m2 on day 1; DES, 1 mg orally on days 5, 6, and 7; and epidoxorubicin, 60 mg/m2, and 5-fluorouracil, 600 mg/m2, on day 8) every 21 days. No significant difference in objective response rates, survival, or progression-free survival was seen between the two regimens. Patients in the DES-CEF arm experienced a higher complete response (CR) rate (24.1% v 16.1%), which reached statistical significance in the case of soft-tissue metastasis (48% v 27.3%; P less than .05) and estrogen receptor-negative tumors (35.7% v 11.1%; P less than .025). Survival and progression-free survival of patients refractory to treatment were not worsened by estrogenic recruitment. In the subset of patients failing after adjuvant polychemotherapy, DES-CEF unexpectedly induced a significantly longer survival (greater than 802 days v 375 days; P = .029) and progression-free survival (239 days v 192 days; P = .041) than CEF. The DES-CEF regimen was more myelotoxic, and 43.3% of the DES-CEF cycles had to be delayed because of leukopenia in comparison with 11.8% of the CEF cycles (P less than .0001). In conclusion, chemotherapy with estrogenic recruitment was able to induce more CRs in certain subsets of patients and a significant prolongation in survival and progression-free survival of patients failing after adjuvant polychemotherapy. These results have been achieved despite a significantly lower dose intensity of chemotherapy.